Power supply system

Abstract

The invention discloses a power supply system. The power supply system comprises an interface and an external power supply circuit, the external power supply circuit comprises a converter, a first capacitor and at least two first power supply sub-circuits; the interface is externally connected with a power supply; the interface is also connected with the input end of the converter; the anodes of the first one-way conductive switches of the first power supply circuits are respectively connected with the output end of the converter through a power line; the cathode of each first one-way conductive switch is connected with the power supply end through a power line. The power supply end is used for connecting at least two loads; the output end of the converter is further connected with one end of the first capacitor through a power line. When the power supply system supplies power to the multiple loads at the same time, the multiple power lines are led out of the first capacitor independently to supply power to the loads respectively, and the problem of instant falling caused by simultaneous work of the loads is successfully solved.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic products, and in particular to a power supply system. Background Art

[0002] When a traditional power supply circuit supplies power to multiple loads at the same time, there is a fatal problem of instantaneous drop when multiple loads flip, which causes mutual interference between the loads due to the instantaneous drop problem, affecting the normal operation of the loads. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a power supply system in order to overcome the above-mentioned defects in the prior art.

[0004] The present invention solves the above technical problems through the following technical solutions:

[0005] A power supply system, comprising: an interface and an external power supply circuit; the external power supply circuit comprises a converter, a first capacitor and at least two first power supply sub-circuits;

[0006] The interface is used for external power supply; the interface is also connected to the input end of the converter; the anode of the first unidirectional conductive switch included in each first power supply subcircuit is connected to the output end of the converter through a power line; the cathode of each first unidirectional conductive switch is connected to the power supply end through a power line; the power supply end is used to connect at least two loads;

[0007] The output end of the converter is also connected to one end of the first capacitor through a power line, and the other end of the first capacitor is grounded.

[0008] Optionally, the power supply system further includes a second capacitor; one end of the second capacitor is connected to the power supply end, and the other end of the second capacitor is grounded.

[0009] Optionally, the external power supply circuit further includes:

[0010] An external power clamp filter module; the input end of the converter is connected to the interface through the external power clamp filter module;

[0011] and / or, an inductor; one end of the first capacitor is connected to the output end of the converter through the inductor;

[0012] And / or, a sampling component; the sampling component comprises a first resistor, a second resistor and a feedforward capacitor, one end of the first resistor is connected to one end of the second capacitor, the other end of the first resistor is respectively connected to one end of the second resistor and a feedback pin of a DC / DC converter chip included in the converter, and the other end of the second resistor is grounded; the feedforward capacitor is connected in parallel with the first resistor;

[0013] And / or, a first switch tube; the anode of each first unidirectional conductive switch is connected to the input end of a first switch tube, and the cathode is connected to the output end of the first switch tube; the control end of the first switch tube is connected to at least one load.

[0014] Optionally, the power supply system further includes a battery power supply circuit, the battery power supply circuit includes a battery and a second power supply sub-circuit, the output end of the battery is respectively connected to the input end of the second power supply sub-circuit, and the output end of the second power supply sub-circuit is connected to the power supply end.

[0015] Optionally, the second power supply subcircuit comprises:

[0016] A second unidirectional conductive switch; an anode of the second unidirectional conductive switch is connected to the input end of the second power supply circuit, and a cathode of the second unidirectional conductive switch is connected to the output end of the second power supply circuit.

[0017] Optionally, the battery power supply circuit further includes:

[0018] A third capacitor; the battery is connected to the input end of each second power supply electronic circuit through one end of the third capacitor, and the other end of the third capacitor is grounded;

[0019] And / or, a fourth capacitor, one end of the fourth capacitor is connected to the power supply end, and the other end of the fourth capacitor is grounded.

[0020] Optionally, the fourth capacitor includes a large-capacity capacitor and / or a high-frequency capacitor connected in parallel; the capacitance value of the large-capacity capacitor is greater than or equal to 1uF, and the capacitance value of the high-frequency capacitor is less than 1uF.

[0021] Optionally, the power supply system is integrated on a PCB board, a through-hole pad penetrating each layer of the PCB board is provided on the PCB board, the fourth capacitor is deployed on the top layer of the PCB board, and a pin of the fourth capacitor is inserted into the through-hole pad; the through-hole pad serves as the power supply end;

[0022] Leading out a first power line from the through-hole pad on the top layer, the first power line also being connected to the cathode of the first unidirectional conductive switch;

[0023] and / or, second power lines are led out from the through-hole pads on the top layer, and each second power line is connected to a first load;

[0024] and / or, a third power line is led out from the through-hole pad on the top layer, and the third power line is also connected to the cathode of the second unidirectional conductive switch;

[0025] And / or, a fourth power line is led out from the through-hole pad on the bottom layer of the PCB board, and each third power line is connected to a second load.

[0026] Optionally, the power supply system further includes a charging module, the output end of the charging module is connected to the charging end of the battery, and the input end of the charging module is connected to one end of the first capacitor;

[0027] And / or, the charging module is connected to at least one load; the load is used to determine whether the output voltage of the battery is within a preset range, and send a charging instruction to the charging module when the output voltage is not within a preset range; the charging module is used to start upon receiving the charging instruction sent by the load to charge the battery;

[0028] And / or, the power supply system also includes a processor, which is electrically connected to the charging module, and the processor is used to determine whether the output voltage of the battery is within a preset range, and send a charging instruction to the charging module when the judgment is no.

[0029] Optionally, the capacitance value of the first capacitor is determined according to at least one of the following: a switching frequency of the converter, an operating current of the load, and a ripple current;

[0030] And / or, the impedance characteristic curve of the first capacitor matches the switching frequency of the converter.

[0031] Optionally, the second power supply subcircuit further includes: a second switch tube; the anode of each second unidirectional conductive switch is connected to the input end of a second switch tube, the cathode is connected to the output end of the second switch tube, and the control end of the second switch tube is connected to at least one load.

[0032] Optionally, the load includes an LTE module and a GPS module; the power supply system further includes a normally closed low voltage dropout linear regulator, and the output end of the first power supply electronic circuit and the output end of the first power supply electronic circuit are connected to the GPS module through the low voltage dropout linear regulator;

[0033] The LTE module is also in communication connection with the low-dropout linear regulator, and the LTE module is used to send an activation signal to the low-dropout linear regulator to activate the low-dropout linear regulator to supply power to the GPS module;

[0034] And / or, the power supply system also includes a processor, which is electrically connected to the low-voltage difference linear regulator, and the processor is used to send an enable signal to the low-voltage difference linear regulator to turn on the low-voltage difference linear regulator to power the GPS module.

[0035] The positive and progressive effect of the present invention is that when the power supply system of the embodiment of the present invention supplies power to multiple loads at the same time, multiple power lines are separately drawn out from the output capacitor (first capacitor) of the converter to supply power to each load respectively, and the output voltage is maintained stable based on the negative feedback and voltage stabilization system of the converter and the principle that the voltage across the capacitor cannot change suddenly and energy is stored and discharged, thereby successfully avoiding the problem of instantaneous drop caused by multiple loads working at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A circuit diagram of a power supply system provided for an exemplary embodiment of the present invention;

[0037] Figure 2 A schematic diagram of an external power supply circuit included in a power supply system provided by an exemplary embodiment of the present invention independently supplying power to an LTE module;

[0038] Figure 3 A schematic diagram of an external power supply circuit included in a power supply system provided by an exemplary embodiment of the present invention, which supplies power to an LTE module and a GPS module at the same time;

[0039] Figure 4 A schematic diagram of a battery power supply circuit included in a power supply system provided by an exemplary embodiment of the present invention independently supplying power to an LTE module;

[0040] Figure 5 A schematic diagram of a battery power supply circuit included in a power supply system provided by an exemplary embodiment of the present invention supplying power to an LTE module and a GPS module at the same time;

[0041] Figure 6 A schematic diagram of an external power supply circuit included in a power supply system provided by an exemplary embodiment of the present invention for supplying power to an LTE module and charging a battery;

[0042] Figure 7 A schematic diagram of an external power supply circuit included in a power supply system provided by an exemplary embodiment of the present invention, which supplies power to an LTE module and a GPS module and charges a battery at the same time;

[0043] Figure 8 A circuit diagram of another power supply system provided for an exemplary embodiment of the present invention;

[0044] Fig. 9A circuit diagram of another power supply system provided for an exemplary embodiment of the present invention;

[0045] Fig.10 A circuit diagram of another power supply system provided for an exemplary embodiment of the present invention;

[0046] Fig.11 A circuit diagram of another power supply system provided for an exemplary embodiment of the present invention;

[0047] Fig.12 A circuit diagram of another power supply system provided for an exemplary embodiment of the present invention;

[0048] Fig.13 A discharge curve diagram of a first capacitor included in a power supply system provided by an exemplary embodiment of the present invention after the converter is powered off;

[0049] Fig.14 A loop gain curve diagram of a converter feedback system measured when a converter has no feedforward capacitor provided by an exemplary embodiment of the present invention;

[0050] Fig.15 A load transient response diagram without a feedforward capacitor is provided for an exemplary embodiment of the present invention;

[0051] Fig.16 A loop gain curve diagram of a converter feedback system measured with a feedforward capacitor provided by an exemplary embodiment of the present invention;

[0052] Fig.17 A load transient response diagram of a converter provided by an exemplary embodiment of the present invention when a 110pF feedforward capacitor is used;

[0053] Fig.18 A cross-sectional view of a PCB board of a power supply system provided by an exemplary embodiment of the present invention;

[0054] Fig.19 A cross-sectional view of a PCB board of another power supply system provided by an exemplary embodiment of the present invention;

[0055] Fig. 20 A top view of a PCB board of a power supply system provided by an exemplary embodiment of the present invention;

[0056] Fig.21 A schematic diagram of an equivalent model of a power supply system including a converter and a load provided by a power supply system according to an exemplary embodiment of the present invention;

[0057] Fig. 22 A curve diagram of impedance frequency of a 150μF tantalum capacitor provided by an exemplary embodiment of the present invention;

[0058] Fig.23 An impedance frequency curve diagram of a 10pF ceramic capacitor provided by an exemplary embodiment of the present invention;

[0059] Fig.24 An impedance frequency curve diagram of a 30pF ceramic capacitor provided by an exemplary embodiment of the present invention;

[0060] Fig.25 An impedance frequency curve diagram of a 100pF ceramic capacitor provided by an exemplary embodiment of the present invention;

[0061] Fig.26 An impedance frequency curve diagram of a 1nF ceramic capacitor provided by an exemplary embodiment of the present invention;

[0062] Fig. 27 An impedance frequency curve diagram of a 10nF ceramic capacitor provided by an exemplary embodiment of the present invention;

[0063] Fig.28 An impedance frequency curve diagram of a 100nF ceramic capacitor provided by an exemplary embodiment of the present invention;

[0064] Fig.29 An impedance frequency curve of a 1uF ceramic capacitor provided by an exemplary embodiment of the present invention;

[0065] Fig.30 An output voltage waveform diagram of a converter provided by an exemplary embodiment of the present invention when the load current is 2A;

[0066] Fig.31 A converter according to an exemplary embodiment of the present invention provides power to an LTE module and a ripple diagram of a power supply voltage at a power supply end of the LTE module under maximum power conditions in a GPRS mode;

[0067] Fig.32 A schematic diagram of a radiation value curve of a vehicle-mounted wireless device in a test frequency band of 30MHz to 1GHz provided by an exemplary embodiment of the present invention;

[0068] Fig.33 An actual power supply circuit diagram of an LTE module provided by an exemplary embodiment of the present invention;

[0069] Fig.34 A waveform diagram of a power transition period of an LTE module provided as an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0070] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples.

[0071] Prefixes such as "first" and "second" are used in the embodiments of the present invention only to distinguish different description objects, and have no limiting effect on the position, order, priority, quantity or content of the described objects. The use of prefixes such as ordinal numbers to distinguish description objects in the embodiments of the present invention does not constitute a limitation on the described objects. For the statement of the described objects, please refer to the description in the context of the claims or embodiments, and no unnecessary limitation should be constituted due to the use of such prefixes. In addition, in the description of this embodiment, unless otherwise specified, the meaning of "plurality" is two or more.

[0072] When a traditional power supply circuit supplies power to multiple loads at the same time, there is a fatal problem of instantaneous drop when multiple loads flip, which causes mutual interference between the loads due to the instantaneous drop problem, affecting the normal operation of the loads. Based on the above problems, an embodiment of the present invention proposes a power supply system, in which the power supply circuit uses the output capacitor of the converter (energy storage capacitor + high-frequency capacitor) to separately lead out multiple power supply lines to power each load respectively. According to the principle that the voltage across the capacitor cannot change suddenly and the energy storage discharge is carried out, the instantaneous drop problem caused by multiple loads working at the same time is successfully avoided. High-frequency capacitor filtering can filter out high-frequency noise generated by each load. With reasonable PCB board layout and wiring, the power supply circuit can further avoid the power drop problem caused by the simultaneous power supply of multiple loads.

[0073] Furthermore, the power supply system of the embodiment of the present invention can realize the function of supplying power to the load by combining an external power supply with a converter, and when the external power supply is powered off, the battery can be used to supply power to the load seamlessly, that is, it can realize seamless switching from the battery to the external power supply to supply power to the load, or realize seamless switching from the external power supply to the battery to supply power to the load, without load power-off, network disconnection, switched power supply voltage drop, etc. At the same time, it can also realize the function of timely charging the battery when the battery is not discharging. The circuit scheme is very simple, low cost, high circuit reliability and not prone to failure problems.

[0074] A power supply system provided by an embodiment of the present invention includes: an interface and an external power supply circuit; the external power supply circuit includes a converter, a first capacitor and at least two first power supply sub-circuits. The interface is used for an external power supply; the interface is also connected to the input end of the converter; the anode of the first unidirectional conductive switch included in each first power supply sub-circuit is connected to the output end of the converter through a power line; the cathode of each first unidirectional conductive switch is connected to the power supply end through a power line respectively; the power supply end is used to connect at least two loads; the output end of the first power supply sub-circuit is used to connect the load. The output end of the converter is also connected to one end of the first capacitor through a power line, and the other end of the first capacitor is grounded.

[0075] It can be understood that the number of the first power supply circuits in this embodiment matches the number of loads. The load may include, but is not limited to, at least one of the following: GPS module 96, WiFi module, Bluetooth module, Zigbee module, Z-wave module, NB-IOT module, Lora module, Sub-GHz module, LTE Cat1e module, eMTC module, GPRS module, NFC module, UWB module, Beidou module, audio module, camera module, LTE module, ARM architecture CPU module, MIPS architecture CPU module, PowerPC architecture CPU module, X86 architecture CPU module, APU (Accelerated Processing Unit, accelerated processor), NPU (Neural-network Processing Unit, embedded neural network processor) module, GPU (Graphic Processing Unit, Graphics Processing Unit) module, DSP (Digital Signal Processing, digital signal processor) module, ASIC (Application Specific Integrated Circuit, application specific integrated circuit), FPGA (Field Programmable Gate Array, field programmable gate array) module, DPU (Data Processing Unit) module, LCD back module, LED back module (mobile phone), LTE module, etc.

[0076] In this embodiment, the first capacitor may be a single capacitor; or may be obtained by connecting a plurality of capacitors in series and / or in parallel, and the capacitances of the capacitors may be the same or different.

[0077] The unidirectional conductive switch may be, but is not limited to, at least one of the following: an isolation diode, a triode, a MOSFET, an IGBT, a thyristor, a relay, etc. The converter may be, but is not limited to, one of the following: a DC / DC converter, a BOOST power converter, a BUCK-BOOST converter, a flyback isolation converter, etc.

[0078] The power supply system of the embodiment of the present invention can be applied to various scenarios, such as electric vehicles, industry, medical treatment, etc.

[0079] Combine the following Figure 1-7 , taking the example that the power supply system supplies power to two loads, the converter adopts a DC / DC converter, and the unidirectional conductive switch adopts an isolation diode, the power supply system is further explained.

[0080] Figure 1-7The power supply system shown provides two power supply modes for the load: external power supply and battery power supply. The external power supply is implemented by an external power supply circuit, and the battery power supply is implemented by a battery power supply circuit. The external power supply circuit mainly includes a DC / DC converter 94, a first capacitor and at least two first power supply circuits, and the first power supply circuit mainly includes an isolation diode. In addition, the external power supply circuit can also include at least one of the following: an external cable 111, an external connector 92, and an external power clamp filter module 91 power supply circuit. The battery power supply circuit includes a battery 93 and at least two second power supply circuits, and each second power supply circuit mainly includes an isolation diode D2 and / or a switch tube Q1.

[0081] In one embodiment, the power supply system further includes a charging module 98, which charges the battery in combination with an external power source, a DC / DC converter, etc.

[0082] In one application scenario, the battery power supply system is applied to the field of electric vehicles, and the interface adopts the car cigarette lighter port 70 (or the power interface of electric bicycles, electric motorcycles, scooters, etc.), the first load is the LTE module 95, and the second load is the GPS module 96. When powered by an external power supply, the 8V-100V power supply from the car cigarette lighter port 70 is injected into the external connector 92 through the external power cable 111, and after internal clamping and filtering of the external power clamping filter module 91, it is input into the DC / DC converter 94, and after the DC / DC converter 94 steps down, the first capacitor C1 (the first capacitor is used as the output capacitor of the DC / DC converter 94) generates a stable voltage Ve1 (generally 5V), and is divided into two paths through the isolation diode D1: one path provides power V3 to the LTE module 95 through the capacitor C5; the other path provides power V4 to the GPS module 96 through the capacitor C4.

[0083] The first capacitor C1 can be, but is not limited to, a 1μF to 100μF ceramic capacitor, a 2.2μF to 2200μF aluminum electrolytic capacitor, or a 2.2μF to 2200μF tantalum capacitor. The parameters of the output capacitor C1 are determined according to the switching frequency of the DC / DC converter 94, the operating current of the load, and the ripple current. The impedance characteristic curve of the ceramic capacitor (the characteristic impedance is as close as possible to the switching frequency of the DC / DC converter 94) should also be considered. If an aluminum electrolytic capacitor is used, not only the impedance characteristic curve should be considered (the operating frequency of the aluminum electrolytic capacitor is below 1MHz, and the switching frequency of the DC / DC converter 94 exceeds 1MHz, so the aluminum electrolytic capacitor is not applicable), but also ESR (series equivalent resistance) should be considered. The DC / DC converter 94 is mainly composed of an input capacitor, a DC / DC converter chip 90, a freewheeling tube (or a built-in freewheeling tube of the DC / DC converter chip 90), an inductor, a sampling circuit, etc.

[0084] The cathode k of the isolation diode D1, the common terminal E2 (i.e., the power supply terminal), pin 1 and the pad of the second capacitor C5, and pin 1 and the pad of the third capacitor C4 are connected, and the anode a of the isolation diode D1 is connected to pin 1 and the pad of the output capacitor C1 in the DC / DC converter 94.

[0085] Function of the isolation diode D1: When the battery 93 supplies power to loads such as the LTE module 95, the low dropout regulator (LDO) module 99 and the GPS module 96 through the isolation diode D2, since the DC / DC converter 94 has no external power supply, the voltage at the output terminal E1 of the DC / DC converter 94 is zero, that is, the anode a voltage of the isolation diode D1 is zero, and the cathode k voltage of the isolation diode D1 is the power input voltage of the LTE module 95 and other loads (that is, the voltage of the common terminal E2). Therefore, the isolation diode D1 is cut off to prevent the battery 93 from directly discharging into the DC / DC converter 94 to generate additional energy consumption when supplying power to the LTE module 95 and other loads.

[0086] Function of the isolation diode D2: When the DC / DC converter 94 supplies power to loads such as the LTE module 95, the low dropout regulator (LDO) module 99 and the GPS module 96 through the isolation diode D1, since the isolation diode D2 is provided between the common terminal E2 of the loads such as the LTE module 95 and the battery 93, the voltage from the DC / DC converter 94 to the common terminal E2 of the loads such as the LTE module 95 after passing through the isolation diode D1 is greater than the voltage of the battery 93 (connected to the anode a of the isolation diode D2), that is, the isolation diode D2 is cut off, thereby preventing the DC / DC converter 94 from directly charging the battery 93 when supplying power to the loads such as the LTE module 95 without any charging management measures.

[0087] A power line is led out from pin 1 of the first capacitor C1 (pin 1 is the positive electrode, output voltage Ve1) to the Vi input terminal of the charging module 98, the Vo output terminal of the charging module 98 is connected to the positive electrode of the battery 93, and the negative electrode of the battery 93 is connected to the ground G (also called grounding). The LTE module output C signal line is connected to the e2 terminal of the charging module 98, which is used to control the on and off state of the charging module 98 (that is, the two states of opening and closing).

[0088] The power supply system can be divided into 6 different working conditions: ① The external power supply circuit supplies power to a load alone, such as the LTE module (such as Figure 2 ② The external power supply circuit supplies power to at least two loads at the same time, for example, the LTE module and the GPS module are powered at the same time (as shown in Figure 3 ③ The battery power supply circuit supplies power to a load alone, such as the LTE module (as shown in Figure 4④ The battery power supply circuit supplies power to at least two loads at the same time, for example, it supplies power to the LTE module and the GPS module at the same time (as shown in FIG. Figure 5 ⑤ The external power supply circuit supplies power to a load and charges the battery at the same time, for example, the power supply circuit supplies power to the LTE module and charges the battery (as shown in Figure 6 ⑥ The external power supply circuit supplies power to at least two loads and charges the battery, for example, the power supply circuit supplies power to the LTE module + GPS module and charges the battery (such as Figure 7 shown).

[0089] The working principle analysis of each working situation is shown below:

[0090] Working condition ①: The external power supply circuit supplies power to one load alone and the battery is not working

[0091] Taking the load as an LTE module as an example, the implementation is: the external power supply circuit supplies power to the LTE module 95 alone, and the battery 93 does not work.

[0092] Figure 2 A schematic diagram of an external power supply circuit supplying power to the LTE module alone is given. When powered by an external power supply, an 8V to 100V power supply from a car cigarette lighter port 70 (here, the interface is a car cigarette lighter port 70 as an example to illustrate the working principle of the power supply system, and the interface can also be implemented in other ways, which will not be described in detail later) is injected into the external connector 92 through an external power cable 111, and after internal clamping (suppressing surges and static electricity) and filtering (filtering out high-frequency noise) of an external power clamp filter module 91, it is input into a DC / DC converter 94, and after voltage reduction by the DC / DC converter 94, a stable voltage Ve1 (generally 5V) is generated by the output terminal E1 of the DC / DC converter 94 (the 1st pin of the output capacitor C1 is connected to the E1 terminal, and the 2nd pin of the output capacitor C1 is connected to the ground G), and a power supply voltage V31 is provided to the LTE module 95 through the isolation diode D1 and the second capacitor C5, and at the same time, the working current in the K1 path of the power line is i11.

[0093] The path of the power line from the output terminal E1 of the DC / DC converter 94 to the common terminal E2 is K1. The LTE module 95 is connected to the antenna 97a through the a1 terminal. When the LTE module 95 is working, the modulated radio frequency signal is radiated to the outside through the antenna 97a, generating electromagnetic waves for wireless communication with the outside world.

[0094] In the K1 path of the power supply line, the main voltage drop is distributed at the cathode a and the anode k of the isolation diode D1, and generally a voltage drop of 0.5V to 0.7V is generated in the isolation diode D1. If the output voltage Ve1 of the output terminal E1 of the DC / DC converter 94 is 5V, it is calculated that the power supply voltage range of the power input terminal vd2 of the LTE module 95 is 5V-0.5V=4.5V, 5V-0.7V=4.3V, that is, the voltage range obtained at the 1st pin of the second capacitor C5 of the LTE module 95 is 4.3V~4.5V.

[0095] Although the common terminal E2 is connected to the input terminal of the low-dropout linear regulator (LDO) module 99, the low-dropout linear regulator (LDO) module 99 is provided with a function of normally shutting down the low-dropout linear regulator (LDO) module 99, so that the GPS module 96 cannot be powered, and the GPS module 96 cannot work normally. The function realized at this time is that the DC / DC converter 94 supplies power to the LTE module 95 alone.

[0096] The enable signal B of the LTE module is connected to the e1 terminal of the low-dropout linear regulator (LDO) module 99. As long as the enable signal B of the LTE module does not send a start signal, the low-dropout linear regulator (LDO) module 99 cannot be turned on, that is, the GPS module 96 cannot work normally.

[0097] The positive electrode of the battery 93 is connected to the anode a of the isolation diode D2, the cathode k of the isolation diode D2 is connected to the cathode k of the isolation diode D1, the common terminal E2, the pin 1 and the pad of the second capacitor C5, and the pin 1 and the pad of the capacitor C4, and the anode a of the isolation diode D1 is connected to the pin 1 and the pad of the first capacitor C1 in the DC / DC converter 94. That is, the positive electrode of the battery 93 is electrically connected to the common terminal E2, the pin 1 and the pad of the second capacitor C5, and the pin 1 and the pad of the capacitor C4 through the isolation diode D2. However, since the voltage from the positive output voltage Ve2 of the battery 93 to the common terminal E2 through the anode a and cathode k of the isolation diode D2 is lower than the voltage from the output terminal E1 to the common terminal E2 in the DC / DC converter 94, the isolation diode D2 is not conducting. As long as the car cigarette lighter port 70 provides power to the LTE module 95 and other loads through the external cable 111 and the external power clamp filter module 91 through the DC / DC converter 94, the battery 93 will not work all the time. In this way, the unidirectional power supply function of the external power supply is realized, and the battery 93 does not work normally, and only serves as an emergency power supply, thereby extending the service life of the battery 93.

[0098] When the LTE module 95 is working and the GPS module 96 and the low-dropout linear regulator (LDO) module 99 are not working, the first capacitor C1 in the DC / DC converter 94 outputs the power supply voltage Ve1, which is directly supplied to the LTE module 95 through the isolation diode D1 and the second capacitor C5, generating a working current i11, which is processed by the baseband chip and the radio frequency chip inside the LTE module 95 to generate a radio frequency signal, which is radiated externally through the LTE antenna 97a, generating radio waves, and realizing the LTE communication function; at this time, the B signal is output through the I / O pin of the LTE module 95 and connected to the EN pin of the low-dropout linear regulator (LDO) 99, so that the low-dropout linear regulator (LDO) 99 is in a closed state, and the GPS module 96 stops working. At this time, the output current of the output capacitor C1 in the DC / DC converter 94 is equal to the LTE module power supply current i11.

[0099] The input terminal Vi of the charging module 98 is connected to the output terminal E1 of the DC / DC converter 94 and the anode a of the isolation diode D1, the output terminal Vo of the charging module 98 is connected to the positive electrode of the battery 93, and the negative electrode of the battery 93 is connected to the ground G (grounded). However, since the LTE module 95 is connected to the enable terminal e2 of the charging module 98 through the enable signal C, as long as the LTE module 95 does not send a charging indication signal, the charging module 98 will not work and the battery 93 is in a disconnected state. In this way, the function of neither charging nor discharging the battery 93 is realized, which greatly extends the service life of the battery 93 (the number of times the battery 93 is charged and discharged will affect its service life).

[0100] The monitoring terminal ad of the LTE module 95 is connected to the output terminal E1 of the DC / DC converter 94. The DC / DC converter 94 supplies power to the LTE module 95 via the isolation diode D1. As long as the LTE module 95 is in normal working state, the monitoring terminal ad of the LTE module 95 will always monitor whether the voltage of the output terminal E1 of the DC / DC converter 94 is within the normal range.

[0101] The isolation diode D1 is generally a common silicon diode or a Schottky diode. The voltage drop of a common silicon diode is about 0.5V to 0.7V, and the voltage drop of a Schottky diode is about 0.2V to 0.5V. When calculating the output voltage of the DC / DC converter 94, the voltage drop (0.2V to 0.7V) of the isolation diode D1 must be taken into account to ensure that the power supply voltage on the second capacitor C5 meets the minimum voltage of the LTE module 95 and ensures the normal operation of the LTE module 95; ensure that the operating voltage on the capacitor C4 meets the low-dropout linear regulator (LDO) 99 to output a normal 1.8V voltage to meet the normal operation of the GPS module 96. The current carrying capacity of the isolation diode D1 is greater than the operating current i11 under the conditions where the LTE module 95 (at full load LTE maximum transmission power) + GPS module 96 work at the same time, and a margin of more than 1 / 4 is reserved to avoid burning out the isolation diode D1.

[0102] ② The external power supply circuit supplies power to at least two loads at the same time and the battery is not working

[0103] Take the load as LTE module and GPS module as an example.

[0104] Realization: The external power supply circuit supplies power to the LTE module and the GPS module at the same time, and the battery does not work.

[0105] Figure 3 The following is a schematic diagram of an external power supply circuit that supplies power to both the LTE module and the GPS module. Figure 2 The difference between the solutions in Figure 3 exist Figure 2The scheme also adds a DC / DC converter 94 to power the low-voltage dropout linear regulator (LDO) module 9 and the GPS module 96. Pin 1 of the second capacitor C5 is connected to the power supply terminal vd1 of the LTE module 95. The operating current from the output terminal E1 of the DC / DC converter 94 to the common terminal E2 is i13, the operating current from the common terminal E2 to the power supply terminal vd1 of the LTE module 95 is i11, and the voltage at pin 1 of the second capacitor C5 of the LTE module 95 is V31; the operating current from the common terminal E3 to pin 1 of the capacitor C4 of the low-voltage dropout linear regulator (LDO) module 99 is i12, and the voltage at pin 1 of the capacitor C4 of the low-voltage dropout linear regulator (LDO) module 99 is V 41; Since the DC / DC converter 94 first supplies power to the LTE module 95 when the power is turned on, after the LTE module 95 is started, the e1 end of the low-voltage difference linear regulator (LDO) module 99 is turned on through the enable signal B of the LTE module, so that the low-voltage difference linear regulator (LDO) module 99 supplies power to the power supply end vd2 of the GPS module, and the GPS module is connected to the GPS antenna 97b through the a2 end to generate electromagnetic waves to receive weak signals transmitted from the earth's near-orbit satellite. Since the operating frequency of the LTE module 95 is 700MHz to 2.7GHz, and the current consumption is large, the response to the power supply is very high, so the voltage fluctuation on the 1 pin of the second capacitor C5 is large, while the working current of the GPS module is small, and the voltage fluctuation on the 1 pin of the capacitor C4 of the low-voltage difference linear regulator (LDO) module 99 is small, so there is a certain difference between the voltage V31 on the 1 pin of the second capacitor C5 and the voltage V41 on the 1 pin of the capacitor C4.

[0106] The input terminal Vi of the charging module 98 is connected to the output terminal E1 of the DC / DC converter 94, the output terminal Vo of the charging module 98 is connected to the positive electrode of the battery 93, and the negative electrode of the battery 93 is connected to the ground G (grounded). However, since the LTE module 95 is connected to the enable terminal e2 of the charging module 98 through the enable signal C, as long as the LTE module 95 does not send a charging indication signal, the charging module 98 will not work, and the battery 93 is in a disconnected state, realizing the function of neither charging nor discharging the battery 93, thereby greatly extending the service life of the battery 93.

[0107] Working condition ③: The battery supplies power to a load alone and reduces the loss in the battery power supply path

[0108] Achieve: A. The battery can supply power to the LTE module independently, reducing the loss in the battery power supply path; B. Reduce the impact of battery power supply and the drop problem caused by a large dynamic response of one load on other loads.

[0109] The following describes how to use a battery to power the LTE module and how to reduce losses in the battery power supply path.

[0110] Figure 4A schematic diagram of the battery powering the LTE module alone is given. The positive electrode of the battery 93 is not only connected to the Vo output terminal of the charging module 98, but also connected to the anode a of the isolation diode D2, and the cathode k of the isolation diode D2 is connected to the cathode k of the isolation diode D1, the common terminal E2, the 1st pin and the pad of the second capacitor C5, and the 1st pin and the pad of the capacitor C4.

[0111] The anode a and cathode k of the isolation diode D2 are connected to the e pin and c pin of the PNP transistor Q1 respectively, that is, a transistor Q1 is connected across the anode a and cathode k of the isolation diode D2 ( Figure 4 The transistor Q1 in the middle is a PNP transistor, which can also be replaced by an NPN transistor, a thyristor, a MOSFET, an IGBT, a relay, etc.). Since the normal voltage of the battery 93 is only between 3.3V and 4.2V, and the stored energy is limited, when the battery 93 supplies power to the LTE module 95, the GPS module 96, etc. through the isolation diode D2, a voltage drop of 0.5V to 0.7V will be generated in the isolation diode D2, resulting in a low working voltage transmitted to the LTE module 95, that is, 3.3V to 4.2V minus a voltage drop of 0.5V to 0.7V, which brings two hazards: the first is that the limited energy stored in the battery 93 is consumed, resulting in a shorter battery life of the battery 93; when the voltage of the battery 93 is as low as 3.3V, if the maximum voltage drop of 0.7V is subtracted, only a working voltage of 2.6V can be obtained in the LTE module 95 and the GPS module 96, L The TE module 95 cannot work normally, so a way must be found to reduce the voltage drop across the anode a and cathode k of the isolation diode D2. Therefore, a transistor Q1 (or MOSFET, IGBT, thyristor, relay, etc., not limited here) of a certain power can be connected across the anode a and cathode k of the isolation diode D2. When the isolation diode D2 is turned on, as long as the LTE module 95 sends an enable signal A to the b pin of the transistor Q1, the transistor Q1 is turned on. At this time, the working current i2 between the battery 93 and the common terminal E2 is divided into two paths, one through the anode a of the isolation diode D2 to the cathode k, and the other through the e pin of the transistor Q1 to the c pin. Finally, the two currents are connected at the cathode k of the isolation diode D2 and the c pin of the transistor Q1 to the common terminal E2. Since the voltage drop between the e pin and the c pin of the transistor Q1 is reduced to 0.1V~0.15V, the working current in the transistor Q1 is dominant.

[0112] a. The isolation diode D2 is selected as a common silicon diode as an example:

[0113] Taking the voltage drop (voltage difference) across the anode a and cathode k of the isolation diode D2 as a minimum of 0.5V and the voltage drop (voltage difference) across the c pin and e pin of the transistor as a minimum of 0.1V as an example, the voltage drop across the anode a and cathode k of the isolation diode D2 / the voltage drop across the c pin and e pin of the transistor can be calculated according to the calculation formula for the parallel connection of different voltage drops of the two devices (similar to solving the equivalent resistance of two resistors in parallel):

[0114]

[0115] Taking the voltage drop (voltage difference) across the anode a and cathode k of the isolation diode D2 as 0.7V at maximum and the voltage drop (voltage difference) across the c pin and e pin of the transistor as 0.15V as an example, the voltage drop across the anode a and cathode k of the isolation diode D2 / the voltage drop across the c pin and e pin of the transistor can be calculated according to the calculation formula for the parallel connection of different voltage drops of the two devices (similar to solving the equivalent resistance of two resistors in parallel):

[0116]

[0117] At this time, the voltage drop range of the power path K2 from the battery 93 to the common terminal E2 is approximately between 0.0833 and 0.1235V. The operating voltage of the power terminal vd1 transmitted from the battery 93 to the LTE module 95 is the battery voltage 3.3V to 4.2V minus the voltage drop of 0.0833 to 0.1235V. The operating voltage range of the LTE module 95 is approximately 3.1765V to 4.1167V. At this time, the consumption of energy stored in the battery 93 has been greatly reduced, and the battery life and service life of the battery 93 have been greatly extended. Even if the voltage of the battery 93 is as low as 3.3V, a voltage of 3.1765V can be obtained at the power terminal vd1 of the LTE module 95, which can basically meet the minimum operating voltage requirement.

[0118] b. The isolation diode D2 is selected as a Schottky diode as an example:

[0119] Taking the voltage drop (voltage difference) across the anode a and cathode k of the isolation diode D2 as a minimum of 0.2V and the voltage drop (voltage difference) across the c pin and e pin of the transistor as a minimum of 0.1V as an example, the voltage drop across the anode a and cathode k of the isolation diode D2 / the voltage drop across the c pin and e pin of the transistor can be calculated according to the calculation formula for the parallel connection of different voltage drops of the two devices (similar to solving the equivalent resistance of two resistors in parallel):

[0120]

[0121] Taking the voltage drop (voltage difference) across the anode a and cathode k of the isolation diode D2 as 0.5V at maximum and the voltage drop (voltage difference) across the c pin and e pin of the transistor as 0.15V as an example, the voltage drop across the anode a and cathode k of the isolation diode D2 / the voltage drop across the c pin and e pin of the transistor can be calculated according to the calculation formula for the parallel connection of different voltage drops of the two devices (similar to solving the equivalent resistance of two resistors in parallel):

[0122]

[0123] At this time, the voltage drop range of the power path K2 from the battery 93 to the common terminal E2 is approximately between 0.06667V and 0.11538V. The working voltage of the power terminal vd1 transmitted from the battery 93 to the LTE module 95 is the battery voltage 3.3V to 4.2V minus the voltage drop of 0.06667V to 0.11538V. The working voltage range of the LTE module 95 is approximately 3.23333V to 4.133332V. At this time, the consumption of energy stored in the battery 93 has been greatly reduced, and the battery life and service life of the battery 93 have been greatly extended. Even if the voltage of the battery 93 is as low as 3.3V, a voltage of 3.23333V can be obtained at the power terminal vd1 of the LTE module 95, which can basically meet the minimum working voltage requirement.

[0124] The following describes how to connect a triode (or MOS tube, IGBT, thyristor, relay, etc.) in parallel at both ends of the isolation diode.

[0125] The economic benefits of connecting the transistor Q1 in parallel at both ends of the isolation diode D2 are described in detail above. The following describes the method and principle of how to connect the transistor Q1 in parallel at both ends of the isolation diode D2.

[0126] The A signal line of the LTE module 95 is connected to the b pin of the transistor Q1, which is used to control the opening or closing of the transistor Q1. When the LTE module 95, the low-dropout regulator (LDO) module 99 and the GPS module 96 are powered by the battery 93, the car cigarette lighter 70 cuts off the connection between the external cable 111, the external power clamp filter module 91 and the DC / DC converter 94, that is, the external power supply does not supply power to the DC / DC converter 94. At this time, the voltage of the cathode k of the isolation diode D1 is higher than the voltage of the anode a, and the isolation diode D1 is not turned on; the voltage of the c pin of the transistor Q1 is higher than the voltage of the e pin, and the transistor Q1 is not turned on. Since the DC / DC converter 94 is not working, the monitoring terminal ad of the LTE module 95 detects that the voltage at the output terminal E1 of the DC / DC converter 94 is basically zero. When the car cigarette lighter 70 provides power to the DC / DC converter 94 through the external cable 111 and the external power clamp filter module 91, the DC / DC converter 94 starts, and the voltage of the first capacitor C1 of the DC / DC converter 94 continues to increase from zero. When the anode a voltage of the isolation diode D1 exceeds the cathode k voltage, the isolation diode D1 is turned on, and at this time, the DC / DC converter 94 supplies power to the LTE module 95, the low-dropout regulator (LDO) module 99, and the GPS module 96 through the isolation diode D1. Since the cathode k voltage of the isolation diode D2 is higher than the anode a voltage, the isolation diode D2 is turned off, and the battery 93 no longer supplies power to the LTE module 95, the low-dropout regulator (LDO) module 99, and the GPS module 96. When the monitoring end ad of the LTE module 95 detects that the voltage Ve1 of the output end E1 of the DC / DC converter 94 reaches a threshold value (for example, 4.4V), the LTE module 95 outputs an A signal to drive the b pin of the transistor Q1, and the transistor Q1 is saturated and turned on. The saturated conduction of the transistor Q1 is used to divide the voltage and current in parallel with the isolation diode D1, thereby reducing the voltage drop and loss of the isolation diode D1, and reducing the problem of instantaneous power failure and network disconnection caused by the drop phenomenon caused by multiple loads working at a large current and jumping.

[0127] c. Take the switch tube Q5 (PMOS tube) as an example:

[0128] Figure 8 Another dual power supply circuit structure is given. Figure 8 The solution uses the switch tube Q5 (PMOS tube) to replace Figure 4The switch tube Q1 (transistor) in the figure also provides a switch tube Q5 (PMOS tube) driving circuit. The switch tube Q5 (PMOS tube) driving circuit is mainly composed of resistor R3, resistor R4, NMOS tube Q6, resistor R5, capacitor C9, and resistor R6. The switch tube Q5 is connected in parallel to the two ends of the isolation diode D2; the s pin of the switch tube Q5 is connected to the anode a of the isolation diode D2, and the d pin of the switch tube Q5 is connected to the cathode k of the isolation diode D2; one end of the resistor R3 is connected to the positive electrode of the battery 93, and the other end is connected to the g pin of the switch tube Q5 and one end of the resistor R4, and the other end of the resistor R4 is connected to the d pin of the NMOS tube Q6, and the s pin of the NMOS tube Q6 is connected to the ground G (grounded). The g pin of the NMOS tube Q6 is connected to one end of the resistor R5, one end of the capacitor C9, and one end of the resistor R6. The other end of the resistor R5 is connected to the ground G (grounded), and the other end of the capacitor C9 is connected to the ground G (grounded). The LTE module 95 outputs the A signal line connected to the 1 pin of the resistor R6 to control the opening or closing of the switch tube Q5. When the external power supply circuit supplies power to the LTE module 95, the low-voltage dropout regulator (LDO) module 99, and the GPS module 96 through the isolation diode D1, the switch tube Q5 is not turned on because the voltage of the d pin of the switch tube Q5 is higher than the voltage of the s pin of the switch tube Q5. When the external power supply circuit is disconnected, the voltage of the anode a of the isolation diode D1 is higher than the voltage of the cathode k, and the battery 93 supplies power to the LTE module 95, the low-voltage dropout regulator (LDO) module 99, and the GPS module 96 through the isolation diode D1. Pin 1 of resistor R3 is connected to output terminal E1 of DC / DC converter 94 through wiring 101, pin 2 of resistor R6 is connected to pin 1 of resistor R7, and pin 2 of resistor R7 is grounded (connected to ground G). A wiring 102 is drawn from monitoring terminal ad of LTE module 95 and connected to pin 2 of resistor R61 and pin 1 of resistor R7, that is, resistor R61 and resistor R7 are divided and then sent to monitoring terminal ad of LTE module 95. When the voltage at the output terminal E1 of the DC / DC converter 94 is lower than a certain threshold, the LTE module 95 determines that the external power supply has been disconnected, and the DC / DC converter 94 stops supplying power to the loads in the board (such as the LTE module 95, the GPS module 96, etc.), and the battery 93 supplies power to the loads in the board (such as the LTE module 95, the GPS module 96, etc.). The LTE module 95 outputs an A signal to drive the NMOS tube Q6 to turn on through the resistor R6, the capacitor C9, and the resistor R5, and the g pin voltage of the switch tube Q5 is pulled down to nearly 0V, and the s pin voltage of the switch tube Q5 is higher than the g pin voltage of Q5, and the switch tube Q5 is turned on. After the switch tube Q5 is turned on, it divides the voltage and current together with the isolation diode D2 to reduce the power consumption of the isolation diode D2.

[0129] The working driving principle of the switch tube Q5 (PMOS tube) and the NMOS tube Q6 is analyzed as follows: Since the voltage of the d pin of the switch tube Q5 is higher than the s pin of the switch tube Q5, the switch tube Q5 is not turned on. When the normal battery 93 does not supply power to the load (such as the LTE module 95, the GPS module 96, etc.), the voltage in the battery 93 is calculated as 3.8V~4V, and the voltage between the d pin and the s pin loaded in the NMOS tube Q6 is about 3.8V~4V. The g pin voltage of the switch tube Q5 is calculated as follows:

[0130]

[0131] Then the voltage difference between the g pin and the s pin of the switch tube Q5 is:

[0132] V GS ≈3.8V-0.03762376237V=-3.7623762376V;

[0133] Table 1 shows the drain-source resistance RDS(ON) value of a certain type of PMOS tube under various conduction conditions. GS Generally, it is between -3.3V and 3.8V, so under the condition of ID = -4.0A, RDS(ON) is about 14mΩ ~ 15.3mΩ. If calculated based on 2.5A current, the voltage drop between the s pin and the d pin of the switch tube Q5 (PMOS tube) is about 2.5Ax14mΩ=35mV=0.035V, 2.5Ax15.3mΩ=38.25mV=0.03825V, calculated based on the maximum voltage drop of 0.03825V.

[0134] Table 1

[0135]

[0136] Take the isolation diode D2 as a common silicon diode and the switch tube Q5 (PMOS tube) as an example for explanation:

[0137] See also Figure 8 , taking the voltage drop (voltage difference) across the anode a and cathode k of the isolation diode D2 as a minimum of 0.5V, the voltage drop (voltage difference) across the s pin and d pin of the switch tube Q5 (PMOS tube) as a minimum of 0.03825V, and the positive voltage range of the battery 93 as an example, the voltage drop across the anode a and cathode k of the isolation diode D2 / the voltage drop across the s pin and d pin of the switch tube Q5 (PMOS tube) can be calculated according to the calculation formula for the parallel connection of different voltage drops of the two devices (similar to solving the equivalent resistance of two resistors in parallel):

[0138]

[0139] Taking the voltage drop (voltage difference) across the anode a and cathode k of the isolation diode D2 as 0.7V at maximum and the voltage drop (voltage difference) across the c pin and e pin of the transistor Q1 as 0.15V as an example, the voltage drop across the anode a and cathode k of the isolation diode D2 / the voltage drop across the c pin and e pin of the transistor can be calculated according to the calculation formula for the parallel connection of different voltage drops of the two devices (similar to solving the equivalent resistance of two resistors in parallel):

[0140]

[0141] At this time, the voltage drop from the positive electrode of the battery 93 to the common terminal E2 is in the range of about 0.001359V to 0.036268V, and the positive electrode voltage range of the battery 93 is 3.3V to 4.2V. After deducting the voltage drop of 0.001359V to 0.036268V, the operating voltage range of the LTE module 95 is about 3.26373V to 4.198641V. Figure 4 Program and Figure 8 Comparison of the schemes in Figure 8 The voltage drop ratio of the isolation diode D2 in parallel with the switch tube Q5 (PMOS tube) Figure 4 The voltage drop of the isolation diode D2 in parallel with the transistor Q1 is smaller, which greatly reduces the voltage drop and loss on the isolation diode D1, and reduces the load-side power supply voltage drop phenomenon when multiple loads consume large currents in dynamic response due to the large internal resistance of the isolation diode D2, causing load power failure and network disconnection problems. At the same time, the loss generated in the power supply path between the battery 93 and the load (such as the LTE module 95, the low-dropout regulator (LDO) module 99 and the GPS module 96, etc.) is greatly reduced, which greatly extends the battery life of the battery 93 and extends the service life of the battery 93.

[0142] The following describes how to reduce the impact of battery power supply and the drop problem caused by a large dynamic response of one load on another load.

[0143] See also Figure 4The monitoring terminal ad of the LTE module 95 will always monitor the voltage Ve1 of the output terminal E1 of the DC / DC converter 94. Once the monitoring terminal ad of the LTE module 95 detects that the voltage is lower than a certain threshold voltage (the threshold voltage can be set), the LTE module 95 will judge that the external power supply circuit has been powered off and the battery 93 is now supplying power to the LTE module 95. An enable signal A is immediately sent to the b pin of the transistor Q1, and the transistor Q1 is turned on, so that the transistor Q1 and the isolation diode D2 are divided by voltage and current to realize the loss of the power path K2 from the battery 93 to the common terminal E2, thereby improving the battery life of the battery 93. At the same time, it ensures that the output voltage Ve2 of the battery 93 is stepped down by the transistor Q1 and the isolation diode D2 to the voltage V32 of the power supply terminal vd1 of the LTE module 95 to meet the minimum operating voltage requirement of the LTE module 95.

[0144] The input terminal Vi of the charging module 98 is connected to the output terminal E1 of the DC / DC converter 94, the output terminal Vo of the charging module 98 is connected to the positive electrode of the battery 93, and the negative electrode of the battery 93 is connected to the ground G (grounded). However, since the LTE module 95 is connected to the enable terminal e2 of the charging module 98 through the enable signal C, as long as the LTE module 95 does not send a charging indication signal, the charging module 98 will not work, and the battery 93 is in a disconnected state, realizing the function of neither charging nor discharging the battery 93, thereby greatly extending the service life of the battery 93.

[0145] Working condition ④: The battery supplies power to multiple loads at the same time

[0146] The load includes an LTE module and a GPS module, and the battery can supply power to the LTE module and the GPS module at the same time.

[0147] Figure 5 The following is a schematic diagram of the battery powering both the LTE module and the GPS module. Figure 4 Comparison of the schemes in Figure 5The solution in the embodiment simultaneously adds a battery 93 to power the low voltage dropout linear regulator (LDO) module 99 and the GPS module 96, and the operating current generated between the power path K2 from the battery 93 to the common terminal E2 is i2. The voltage generated at the pin 1 of the second capacitor C5 of the LTE module 95 is V32, and the operating current generated between the common terminal E2 and the power terminal vd1 of the LTE module 95 is i21; the voltage generated at the pin 1 of the capacitor C4 of the low voltage dropout linear regulator (LDO) module 99 is V42, and the operating current generated between the common terminal E2 and the pin 1 of the capacitor C4 of the low voltage dropout linear regulator (LDO) 99 is i22. The relationship between the working current i21 generated between the common terminal E2 and the power terminal vd1 of the LTE module 95, the working current i21 generated between the common terminal E2 and the power terminal vd1 of the LTE module 95, and the working current i22 generated between the common terminal E2 and pin 1 of the capacitor C4 of the low-voltage difference linear regulator (LDO) 99 satisfies: i2=i21+i22.

[0148] At this time, the LTE module 95 sends a start signal A to the enable terminal e1 of the low-voltage difference linear regulator (LDO) 99, and the low-voltage difference linear regulator (LDO) 99 starts to supply power to the power terminal vd2 of the GPS module 96. The GPS module 96 works normally and is connected to the GPS antenna through the a2 terminal. The GPS antenna receives the weak signal transmitted by the earth orbit satellite and provides location information to the vehicle-mounted equipment to realize the GPS positioning function.

[0149] Figure 5 The other parts of the solution have the same functions as Figure 4 Basically the same, no repetitive description is given.

[0150] Working condition ⑤: External power supply circuit supplies power to a load and charges the battery

[0151] Figure 6 The schematic diagram of the external power supply circuit for powering the LTE module and charging the battery is given. Figure 2 Comparison of the schemes in Figure 6 The solution in the embodiment also adds an external power supply circuit and a functional signal flow diagram of the charging module 98 charging the battery 93.

[0152] The battery voltage detection terminal ab of the LTE module 95 is connected to the positive output terminal of the battery 93 (that is, the 1st pin and the pad of the third capacitor C2). As long as the LTE module 95 is in normal working condition, the battery voltage detection terminal ab of the LTE module 95 will always monitor the output voltage of the battery 93 to determine whether the working condition of the battery 93 is normal: ① Whether the battery 93 is lower than the discharge threshold voltage (for example, the lithium battery discharge threshold voltage is 3.3V) during the process of supplying power to the LTE module 95 and other loads (discharging process). If it is lower than the discharge threshold voltage (for example, the lithium battery discharge threshold voltage is 3.3V), the battery 93 power supply system must be shut down and disconnected; because the battery 93 is lower than the discharge threshold voltage (for example, the lithium battery discharge threshold voltage is 3.3V), the output voltage Ve2 of the battery 93 will be lower than the normal value, and the LTE module 95 and other loads will obtain a voltage lower than the working power supply voltage, resulting in failure to work normally; at the same time, the battery 93 is lower than the discharge threshold voltage (for example, the lithium battery discharge threshold voltage is 3.3V). ② When the external power supply circuit charges the battery 93 via the charging module 98, the battery voltage detection terminal a of the LTE module 95 constantly monitors whether the output voltage of the battery 93 exceeds the charging threshold voltage (for example, the charging threshold voltage of the lithium battery is 4.2V). Once the battery voltage detection terminal a of the LTE module 95 constantly monitors whether the output voltage of the battery 93 exceeds the charging threshold voltage (for example, the charging threshold voltage of the lithium battery is 4.2V), the LTE module 95 sends a shutdown signal C to the enable terminal e2 of the charging module 98, so that the charging module 98 stops charging the battery 93, thereby avoiding affecting the service life of the battery 93 and preventing the battery 93 from being overcharged, causing fire, explosion and other serious accidents.

[0153] Therefore, the function of the battery voltage detection terminal ab of the LTE module 95 is very important. It can not only ensure the safety of the battery 93 during the charging process (not overcharging), but also ensure the safety of the battery 93 during the discharging process (not overdischarging), while extending the service life of the battery 93.

[0154] The relationship between the working current i14 from the output terminal E1 of the DC / DC converter 94 to the anode a of the isolation diode D1, the charging current i15 from the anode a of the isolation diode D1 to the Vi terminal of the charging module 98, the Vo terminal of the charging module 98 to the positive electrode of the battery 93, the negative electrode of the battery 93 to the ground, the anode a of the isolation diode D1, the cathode k of the isolation diode D1 to the working current i11 between the 1st pin of the second capacitor C5 of the LTE module 95 satisfies:

[0155] i14=i15+i11;

[0156] When the battery voltage detection terminal ab of the LTE module 95 detects that the positive output terminal Ve2 of the battery 93 is lower than the threshold voltage of the battery 93 (for example, the discharge threshold voltage of the lithium battery is 3.3V), the C-terminal signal routing of the LTE module 95 sends a start signal C to the enable terminal e2 of the charging module 98, and the charging module 98 starts the function of charging the battery 93. The LTE module 95 does not send a start signal A to the enable terminal e1 of the low-dropout linear regulator (LDO) 99 of the LTE module 95, the low-dropout linear regulator (LDO) 99 is in the off state, and the GPS module 96 is in the power-off state. Since the voltage of the positive electrode voltage Ve2 of the battery 93 in the charging state through the isolation diode D2 / transistor Q1 to the common terminal E2 does not exceed the voltage of the output terminal E1 of the DC / DC converter 94 through the isolation diode D1 to the common terminal E2, the isolation diode D2 / transistor Q1 is in the cut-off state, and the battery 93 in the charging state does not discharge. The external power supply circuit provides power to the LTE module and charges the battery. The voltage at pin 1 of the second capacitor C5 of the LTE module 95 is V34, and the voltage at pin 1 of the capacitor C4 of the low dropout linear regulator (LDO) 99 is V44.

[0157] Figure 6 The other parts of the solution have the same functions as Figure 2 Basically the same, no repetitive description is given.

[0158] Working condition ⑥: External power supply circuit supplies power to multiple loads and charges batteries

[0159] Take the example of powering the LTE module and GPS module. Figure 7 The schematic diagram of the external power supply circuit for powering the LTE module + GPS module and charging the battery is given. Figure 6 Comparison of the schemes in Figure 7 The solution in the embodiment also adds the function of supplying power to the low-dropout linear regulator (LDO) 99 and the GPS module. The working current i16 from the output terminal E1 of the DC / DC converter 94 to the anode a of the isolation diode D1, the charging current i15 from the anode a of the isolation diode D1 to the Vi terminal of the charging module 98, the Vo terminal of the charging module 98 to the positive electrode of the battery 93, the negative electrode of the battery 93 to the ground, the working current i11 from the common terminal E2 to the second capacitor C5 of the LTE module 95, the power supply terminal vd1 of the LTE module 95, and the working current i12 from the common terminal E2 to the capacitor C4 of the low-dropout linear regulator (LDO) 99 satisfies the following relationship:

[0160] i16=i15+i11+i12;

[0161] When the battery voltage detection terminal ab of the LTE module 95 detects that the positive output terminal Ve2 of the battery 93 is lower than the threshold voltage of the battery 93 (for example, the discharge threshold voltage of the lithium battery is 3.3V), the C-terminal signal routing of the LTE module 95 sends a start signal C to the enable terminal e2 of the charging module 98, and the charging module 98 starts the function of charging the battery 93. The LTE module 95 sends a start signal A to the enable terminal e1 of the low-dropout linear regulator (LDO) 99, the low-dropout linear regulator (LDO) 99 is in the on state, and the GPS module 96 is in the working state. Since the voltage of the positive electrode voltage Ve2 of the battery 93 in the charging state through the isolation diode D2 / transistor Q1 to the common terminal E2 does not exceed the voltage of the output terminal E1 of the DC / DC converter 94 through the isolation diode D1 to the common terminal E2, the isolation diode D2 / transistor Q1 is in the cut-off state, and the battery 93 in the charging state does not discharge. The external power supply circuit provides power to the LTE module and the GPS module and charges the battery. The voltage at the pin 1 of the second capacitor C5 of the LTE module 95 is V35, and the voltage at the pin 1 of the capacitor C4 of the low dropout linear regulator (LDO) 99 is V45.

[0162] Figure 6 The other parts of the solution have the same functions as Figure 5 Basically the same, no repetitive description is given.

[0163] The following describes how to implement the power supply system to automatically switch and seamlessly supply power to the load.

[0164] a. Automatically switch from external power supply circuit to battery power supply to supply power to the load.

[0165] like Figure 2 , Figure 4 As shown, the battery 93 supplies power to the LTE module 95 separately via the third capacitor C2, the isolation diode D2, the fourth capacitor C3, and the second capacitor C5, which belongs to a separate and complete battery power supply system path. The external power supply supplies power to the LTE module 95 separately via the car cigarette lighter 70, the external cable 111, the external power clamp filter module 91, the DC / DC converter 94, the isolation diode D1, the fourth capacitor C3, and the second capacitor C5, which belongs to a separate and complete external power supply system path. The battery power supply system path and the external power supply system path are two independent power supply system paths.

[0166] like Figure 2As shown, once the car cigarette lighter 70 is disconnected from the external power supply, the DC / DC converter 94 will stop working. Since there is no DC / DC converter 94 to replenish energy for the output capacitor C1 of the DC / DC converter 94, as the discharge voltage of the output capacitor C1 of the DC / DC converter 94 continues to decrease, when the discharge voltage of the output terminal E1 of the DC / DC converter 94 is lower than the voltage from the battery 93 to the 1st pin of the third capacitor C2 (voltage is Ve2), the anode a of the isolation diode D2, the cathode b of the isolation diode D2 to the common terminal E2, the isolation diode D1 is cut off at this time, and the battery 93 is used to supply power to the LTE module 95 through the isolation diode D2. The path from the battery 93, the isolation diode D2, the transistor Q1 to the common terminal E2 is K2, and the working current i21 generated in the K2 path is the working current flowing into the LTE module 95. In this way, the power supply from the external power supply circuit to the battery for the LTE module 95 is automatically switched, and the connection is seamless. During the switching process, the LTE module 95 does not have a power outage problem, and the LTE module 95 will not be disconnected from the network. The load power supply function is seamlessly switched from the external power supply circuit to the battery, without manual intervention, saving costs, and having reliable performance.

[0167] Fig.13 A discharge curve diagram of the first capacitor C1 after the external power supply is cut off is given.

[0168] Take the voltage Ve1 of the output terminal E1 of the DC / DC converter 94 as an example, which normally outputs 5V, the battery voltage is 4.2V, the voltage drop between the anode a and the cathode b of the isolation diode D1 is 0.7V (ordinary silicon diode), and the voltage drop between the anode a and the cathode b of the isolation diode D2 is 0.7V (ordinary silicon diode) as an example for explanation:

[0169] When the car cigarette lighter 70 is disconnected from the external power supply, the voltage Ve1 at the output terminal E1 of the DC / DC converter 94 is still 5V. At this time, the discharge voltage of the first capacitor C1 from the DC / DC converter 94 obtained at the common terminal E2 is Ve1-0.7V=5V-0.7V=4.3V, that is, the voltage at the common terminal E2 (connected to the 1st pin of the fourth capacitor C3) is 4.3V; and at this time, the voltage Ve2 (4.2V) of the battery 93 at the common terminal E2 through the third capacitor C2 and the isolation diode D2 is Ve2-0.5V=4.2V-0.7V=4.2V-0.7V=3.5V. The voltage Ve1 at the output terminal E1 of the C / DC converter 94 is 4.3V from the isolation diode D1 to the common terminal E2, which is greater than the voltage Ve2 of the battery 93 at the common terminal E2 of 3.5V through the third capacitor C2 and the isolation diode D2. Therefore, although the DC / DC converter 94 does not continue to charge the first capacitor C1 of the DC / DC converter 94 (replenish energy to the first capacitor C1 of the DC / DC converter 94), the first capacitor C1 of the DC / DC converter 94 still continues to discharge to the common terminal E2 through the isolation diode D1, and at the same time charges the fourth capacitor C3 and the second capacitor C5 to power the LTE module 95. Until the voltage Ve1 at the output terminal E1 of the DC / DC converter 94 is lower than the threshold value of 3.5V through the isolation diode D1 to the common terminal E2, at this time, the voltage Ve2 (4.2V) of the battery 93 is discharged to the common terminal E2 through the third capacitor C2 and the isolation diode D2, and the fourth capacitor C3 and the second capacitor C5 are charged to supply power to the LTE module 95, and at this time, the voltage Ve1 at the output terminal E1 of the DC / DC converter 94 is reversely estimated to be 3.5V+0.7V=4.2V, that is, when the discharge voltage of the output terminal E1 of the DC / DC converter 94 is lower than 4.2V, the voltage Ve2 (4.2V) of the battery 93 is discharged to the common terminal E2 through the third capacitor C2 and the isolation diode D2, and the fourth capacitor C3 and the second capacitor C5 are charged to supply power to the LTE module 95. After the DC / DC converter 94 is powered off, the first capacitor C1 of the DC / DC converter 94 continues to charge the fourth capacitor C3, the second capacitor C5 and supply power to the LTE module 95. When the power supply is lower than a certain threshold, the power supply mode of the DC / DC converter 94 is automatically switched to the battery 93 power supply mode. During the switching process, there is no load power failure or LTE module 95 disconnection.

[0170] Take the voltage Ve1 of the output terminal E1 of the DC / DC converter 94 as an example, which normally outputs 5V, the battery voltage is 4.2V, the voltage drop between the anode a and the cathode b of the isolation diode D1 is 0.5V (Schottky diode), and the voltage drop between the anode a and the cathode b of the isolation diode D2 is 0.5V (Schottky diode) as an example for explanation:

[0171] When the external power supply is disconnected from the cigarette lighter 70 of the automobile, the voltage Ve1 at the output terminal E1 of the DC / DC converter 94 is still 5V. At this time, the discharge voltage of the first capacitor C1 from the DC / DC converter 94 obtained at the common terminal E2 is Ve1-0.5V=5V-0.5V=4.5V, that is, the voltage at the common terminal E2 is 4.5V; and at this time, the voltage Ve2 (4.2V) of the battery 93 is Ve2-0.7V=4.2V-0.5V=4.2V-0.5V=3.7V at the common terminal E2 through the third capacitor C2 and the isolation diode D2. The voltage Ve1 at the output terminal E1 of the converter 94 is 4.5V from the isolation diode D1 to the common terminal E2, which is greater than the voltage Ve2 of the battery 93 at the common terminal E2 of 3.7V through the third capacitor C2 and the isolation diode D2. Therefore, although the DC / DC converter 94 does not continue to charge the first capacitor C1 of the DC / DC converter 94 (replenish energy to the first capacitor C1 of the DC / DC converter 94), the first capacitor C1 of the DC / DC converter 94 still continues to discharge to the common terminal E2 through the isolation diode D1, and at the same time charges the fourth capacitor C3 and the second capacitor C5 to power the LTE module 95. Until the voltage Ve1 at the output terminal E1 of the DC / DC converter 94 is lower than the threshold value of 3.7V through the isolation diode D1 to the common terminal E2, at this time, the voltage Ve2 (4.2V) of the battery 93 is discharged to the common terminal E2 through the third capacitor C2 and the isolation diode D2, and the fourth capacitor C3 and the second capacitor C5 are charged to supply power to the LTE module 95, and at this time, the reverse estimation of the voltage Ve1 at the output terminal E1 of the DC / DC converter 94 is 3.7V+0.5V=4.2V, that is, when the discharge voltage of the output terminal E1 of the DC / DC converter 94 is lower than 4.2V, the voltage Ve2 (4.2V) of the battery 93 is discharged to the common terminal E2 through the third capacitor C2 and the isolation diode D2, and the fourth capacitor C3 and the second capacitor C5 are charged to supply power to the LTE module 95. After the DC / DC converter 94 is powered off, the first capacitor C1 of the DC / DC converter 94 continues to charge the fourth capacitor C3, the second capacitor C5 and supply power to the LTE module 95. When the power supply is lower than a certain threshold, the power supply mode of the DC / DC converter 94 is automatically switched to the battery 93 power supply mode. During the switching process, there is no load power failure or LTE module 95 disconnection.

[0172] b. Automatically switch from battery to external power supply circuit to power the load

[0173] like Figure 2 , Figure 4As shown, if the battery 93 supplies power to the LTE module 95 separately through the third capacitor C2, the isolation diode D2 (and, or transistor Q1), the fourth capacitor C3, and the second capacitor C5, once the car cigarette lighter 70 is connected to the external power supply, the DC / DC converter 94 will start working immediately, and at the same time, the DC / DC converter 94 will replenish energy to the first capacitor C1 of the DC / DC converter 94. As the charging voltage of the first capacitor C1 of the DC / DC converter 94 continues to increase, when the charging voltage of the output terminal E1 of the DC / DC converter 94 is connected to the anode a of the isolation diode D1 and the isolation diode C5, the DC / DC converter 94 will start working immediately. When the voltage from the cathode b of the tube D1 to the common terminal E2 is higher than the voltage from the battery 93 to the 1-pin of the third capacitor C2 (the voltage is Ve2), the anode a of the isolation diode D2, the cathode b of the isolation diode D2 (and / or the e-pin and c-pin of the transistor Q1) to the common terminal E2, the isolation diode D1 is turned on, and the DC / DC converter 94 supplies power to the LTE module 95 via the isolation diode D1. The path from the DC / DC converter 94 and the isolation diode D1 to the common terminal E2 is K1, and the working current i11 generated in the K2 path is the working current flowing into the LTE module 95.

[0174] Take the voltage Ve1 of the output terminal E1 of the DC / DC converter 94 as an example, which normally outputs 5V, the battery voltage is 4.2V, the voltage drop between the anode a and the cathode b of the isolation diode D1 is 0.5V (Schottky diode), and the voltage drop between the anode a and the cathode b of the isolation diode D2 is 0.5V (Schottky diode) as an example for explanation:

[0175] When the car cigarette lighter port 70 is powered off, the voltage Ve2 (4.2V) of the battery 93 is obtained through the third capacitor C2 and the isolation diode D2 at the common terminal E2, which is Ve2-0.5V=4.2V-0.5V=4.2V-0.5V=3.7V, that is, the power supply voltage obtained by the power supply terminal vd1 (load terminal) of the LTE module 95 is 3.7V. Once the car cigarette lighter 70 is connected to an external power source, the DC / DC converter 94 will start working, and at the same time, the DC / DC converter 94 will replenish energy to the first capacitor C1 of the DC / DC converter 94. As the charging voltage of the first capacitor C1 of the DC / DC converter 94 continues to increase, when the discharge voltage of the output terminal E1 of the DC / DC converter 94 exceeds the threshold voltage of 3.7V through the anode a of the isolation diode D1 and the cathode b of the isolation diode D1 to the common terminal E2, the isolation diode D2 is cut off, that is, the battery 93 stops supplying power to the power supply terminal vd1 (load terminal), and automatically switches to the external power supply circuit for power supply. It can be reversely deduced: the voltage of the common terminal E2 is 3.7V + the voltage drop of the isolation diode D1 is 0.5V = 4.2V, that is, during the period when the DC / DC converter 94 replenishes energy to the first capacitor C1 of the DC / DC converter 94, as long as the voltage of the output terminal E1 of the DC / DC converter 94 exceeds the charging threshold voltage of 4.2V, the battery stops supplying power to the power terminal vd1 (load terminal) and automatically switches to the external power supply circuit for power supply. In this way, the power supply from the battery to the LTE module 95 is automatically switched to the external power supply circuit for powering the LTE module 95, and it is seamless. During the switching process, the LTE module 95 does not have a power outage problem, and there will be no LTE disconnection phenomenon, realizing the seamless connection from the battery to the external power supply circuit to supply power to the load, without manual intervention, saving costs, and reliable performance.

[0176] Fig.10 The circuit diagram of the power supply system of the multi-load mainly composed of microprocessor module + LTE module + GPS module is given. Figure 7 Comparison of the schemes in Fig.10 The solution in the embodiment adds a microprocessor 91, a low dropout linear regulator (LDO) module 78 and other loads. Figure 7 The LTE module 95 in the embodiment can be integrated with the microprocessor module 91, or the LTE module 95 can be separated from the microprocessor 91. If the LTE module 95 has a built-in microprocessor module 91, the monitoring terminal ad (used to monitor the output voltage of the DC / DC converter 94) of the LTE module 95 and the battery voltage detection terminal ab of the LTE module 95 can be integrated into the LTE module 95, and the microprocessor module 100 does not need to be separately provided. Fig.10In the solution, the microprocessor module 100 is not provided inside the LTE module 95, and the microprocessor module 100 is separated from the LTE module 95, and a set of low-dropout linear regulator (LDO) modules 78 is added to provide power to the microprocessor module 100. The monitoring terminal ad of the microprocessor module 100 is used to monitor the output voltage Ve1 of the DC / DC converter 94; the battery voltage detection terminal ab of the microprocessor module 100 is used to detect the output voltage Ve2 of the positive electrode of the battery. The microprocessor module 100 outputs a C signal line connected to the e2 terminal of the charging module 98, and is used to control the on / off state of the charging module 98 (i.e., the two states of on and off); the microprocessor module 100 outputs a B signal line connected to the e1 terminal of the low-voltage difference linear regulator (LDO) module 99, and is used to control the on / off state of the low-voltage difference linear regulator (LDO) module 99 and the GPS module 96 (i.e., the two states of on and off); the microprocessor module 100 outputs an A signal line connected to the b pin of the transistor Q1, and is used to control the transistor Q 1 on / off state: When the e pin of transistor Q3 is connected to the common terminal E2 (that is, the 1 pin of the second capacitor C5), the c pin of transistor Q3 is connected to the 1 pin of capacitor C6 and the power supply terminal vd1 of LTE module 95, as long as the microprocessor module 100 outputs the A signal to turn on and off the b pin of transistor Q1, the LTE module 95 can be turned on and off; the microprocessor module 100 outputs the M signal routing and is connected to the b pin of transistor Q3, which is used to control the on / off state of transistor Q2 and LTE module 95 (that is, the two states of on and off). Transistor Q1, transistor Q2, and transistor Q3 can also be replaced by MOSFET, IGBT, thyristor, relay, etc.

[0177] Fig.10 The microprocessor module 100 in the solution outputs the A signal routing, B signal routing, and C signal routing functions. Figure 7 The functions of the LTE module 95 output A signal routing, B signal routing, and C signal routing in the solution are the same. Fig.10 The functions of the monitoring terminal ad and the battery voltage detection terminal ab of the microprocessor module 100 in the scheme are similar to Figure 7 The functions of the monitoring terminal ad of the LTE module 95 and the battery voltage detection terminal ab in the solution are the same.

[0178] and Figure 7 Comparison of the schemes in Fig.10 The microprocessor module 100 in the scheme has another outstanding advantage that the on / off state of the transistor Q1 and the LTE module can be completely controlled through the M signal routing. The I / O pins of the microprocessor module 100 can not only control the on / off of the charging module 98, the LTE module 95, and the GPS module 96 individually, but also use the internal delay of the I / O pins of the microprocessor module 100 to realize the power-on timing function of each module when it is turned on.

[0179] The following describes the relationship between the GPS module and the low-dropout linear regulator (LDO), BUCK or BOOST power module, and the relationship between the LTE module and the BUCK or BOOST power module.

[0180] Figure 2 to Figure 8 In the illustrated solution, the GPS module 96 and the low-dropout linear regulator (LDO) 99 are described as two separate parts. The GPS module 96 may also include the low-dropout linear regulator (LDO) 99, that is, only the GPS module needs to be described, and the low-dropout linear regulator (LDO) 99 does not need to be listed separately. In some solutions, the GPS module 96 and the low-dropout linear regulator (LDO) 99 are separated, but in some solutions, the GPS chip in the GPS module 96 has a built-in low-dropout linear regulator (LDO) or a BUCK power supply circuit, a BOOST power supply circuit, etc. Figure 2 to Figure 8 The low dropout linear regulator (LDO) 99 in the solution shown can also be replaced by a BUCK power supply circuit or a BOOST power supply circuit. Figure 2 to Figure 8 The loads such as the LTE module and GPS module in the solution shown may also have built-in low-dropout linear regulators (LDO), BUCK power supply circuits, and BOOST power supply circuits, without limitation here.

[0181] The following introduces a low-cost external power supply solution and charging circuit solution.

[0182] Fig.11 The following is a schematic diagram of the external power supply circuit that supplies power to the LTE module and GPS module separately. Fig.11 that is Figure 2 to Figure 8 The internal circuit of the DC / DC converter chip 90, the peripheral circuit composition of the DC / DC converter 94, and the internal composition of the charging module 98 are displayed. Fig.11 The battery is a lithium-ion battery, a BUCK power topology, and a linear charging chip is used as an example to illustrate the charging solution. The type of battery 93 and the structure of the power topology are not limited. The linear charging chip forming a linear charging module solution can also be changed to a linear charging solution composed of discrete components. Fig.11As shown, the DC / DC converter 94 is mainly composed of an input capacitor C11, a DC / DC converter chip 90, a sampling component 88, an inductor L1, a first capacitor C1, etc. The DC / DC converter chip 90 has built-in functional circuits such as an upper power switch Q8, a lower power switch Q9, a reference voltage source VREF, a clock generator 84, etc. The drain of the upper power switch Q8 is connected to the power input pin Vin of the DC / DC converter chip 90, the source of the upper power switch Q8 is connected to the pin SW of the DC / DC converter chip 90 and the drain of the lower power switch Q9, the source of the lower power switch Q9 is connected to the pin G9 of the DC / DC converter chip 90, and the DC / DC converter The pin G9 of the chip 90 is connected to the system ground of the DC / DC converter 94, for example, the pin G9 of the DC / DC converter chip 90 is connected to the ground pin G8 of the external connector 92, the ground pin G7 of the external power clamp filter module 91, the 2nd pin of the input capacitor C11, the 2nd pin of the first capacitor C1, the 2nd pin of the second capacitor C5, the ground pin G4 of the LTE module 95, the 2nd pin of the capacitor C4, the ground pin G2 of the low dropout regulator (LDO) module 99, and the ground pin G3 of the GPS module 96. The pin SW of the DC / DC converter chip 90 is connected to the 1st pin of the inductor L1, and the 2nd pin of the inductor L1 is connected to the 1st pin of the first capacitor C1. The sampling component 88 is placed close to the feedback pin FB of the DC / DC converter chip 90. A wire 86 is led out from the feedback pin FB of the DC / DC converter chip 90 to one end of a sampling component 88 , and a sampling wire 87 is led out from the other end of the sampling component 88 to the pin 1 of the first capacitor C1 .

[0183] Taking the output voltage V1 of the output terminal E1 of the DC / DC converter 94 as 4.436V as an example, how to set the output voltage V1 of the DC / DC converter 94 (taking the BUCK power supply as an example) is described.

[0184] Fig.12 Another schematic diagram is given of an external power supply circuit that supplies power to the LTE module and GPS module separately. Fig.12 is Fig.11On the basis of the scheme, the specific composition of the sampling component 88 is given in detail. The sampling component 88 is mainly composed of a resistor R1, a resistor R2, and a feedforward capacitor C8. Pin 2 of the resistor R1 is connected to pin 1 of the resistor R2, and pin 2 of the resistor R2 is connected to ground G (grounded). Pin 1 of the feedforward capacitor C8 is connected to pin 1 of the resistor R1, and pin 2 of the capacitor C8 is connected to pin 2 of the resistor R1. A sampling line 87 is led out from pin 1 of the first capacitor C1 and connected to pin 1 of the feedforward capacitor C8 and pin 1 of the resistor R1. A line 86 is led out from the feedback pin FB of the DC / DC converter chip 90 and connected to pin 2 of the feedforward capacitor C8, pin 1 of the resistor R2, and pin 2 of the resistor R1. C1 is an advanced phase compensation capacitor at the feedback end, which has the function of accelerating and stabilizing the output voltage V1. The following takes the output voltage V1 of the output terminal E1 of the DC / DC converter 94 as 4.436V as an example to illustrate how to set the output voltage of the BUCK. Assume that the reference power supply VREF of the DC / DC converter chip 90 is 0.8V, R1=100KΩ, and R2=22KΩ.

[0185] Output voltage V1 = VREF × (R1 / R2+1) = 0.8V × (100KΩ / 22KΩ+1) = 4.436V.

[0186] The charging module 98 (using a linear charging chip to form the charging module) has a built-in power switch Q7 (only a triode is used as an example for explanation, and the type of power switch Q7 is not limited, such as thyristor, IGBT, MOSFET, relay, etc.), the e pin of the power switch Q7 is connected to the Vi input terminal of the charging module 98, the c pin of the power switch Q7 is connected to the Vo output terminal of the charging module 98, the b pin of the power switch Q7 is connected to the internal control circuit 72, and the internal control circuit 72 is connected to the e2 terminal of the charging module 98. The power line is led out from the 1 pin (1 pin is the positive pole, the output voltage Ve1) of the first capacitor C1 of the DC / DC converter 94 to the Vi input terminal of the charging module 98, the Vo output terminal of the charging module 98 is connected to the positive pole of the battery 93, and the negative pole of the battery 93 is connected to the ground G (ground). The LTE module output C signal routing is connected to the e2 terminal of the charging module 98, which is used to control the on and off state of the charging module 98 (that is, the two states of open and closed).

[0187] Table 2 shows the characteristics of a certain model of LTE module power supply. From Table 2, it can be seen that the minimum operating voltage of LTE module 95 is 3.2V, the typical value is 3.8V, and the maximum value is 4.4V; the maximum instantaneous drop of the LTE module under the maximum RF output condition is 0.4V (400mV); the maximum value of the digital transmission current is 589mA in EGSM900 1D / 4U PCL=5 mode, the maximum value of the digital transmission current is 541mA in WCDMA B1HSDPA541 mode, and the maximum value of the digital transmission current is 710mA in LTE B3 mode; in LTEDRX=5 mode, the maximum value of the standby current is 5.5μA; the instantaneous current of RF transmission reaches 3A.

[0188] Table 2

[0189]

[0190]

[0191] Continue reading Figure 2 to Figure 8 , Fig.11 As shown, the parameters of the sampling component 88 are adjusted to obtain a voltage of 4.35V to 4.7V at the output terminal E1 of the DC / DC converter 94. After isolation by the isolation diode D1 (generating a voltage drop of about 0.7V), a voltage of 3.736V (4.436V-0.7V=3.736V) to 4.0V (4.7V-0.7V=4.0V) is obtained at the vd1 terminal of the LTE module 95. The voltage of 3.736V to 4.0V is not only in the 3. The operating voltage range is 2V to 4.4V, and it is very close to the typical operating voltage of 3.8V of the LTE module 95. The maximum voltage at the vd1 end of the LTE module 95 is 4.0V, and a 0.4V margin must be reserved. Otherwise, once the voltage at the output end E1 of the DC / DC converter 94 exceeds 5.1V, minus the 0.7V voltage drop of the isolation diode D1, the voltage at the vd1 end of the LTE module 95 will exceed the maximum voltage of 4.4V, causing damage to the LTE module 95.

[0192] The maximum voltage of the battery 93 (taking a lithium-ion battery as an example) when fully charged is 4.2V, so the minimum output voltage of the output terminal E1 of the DC / DC converter 94 must be greater than 4.2V. Taking into account that the power switch Q7 inside the charging module 98 (taking a charging module composed of a linear charging chip as an example) still has a voltage drop of 0.1V to 0.15V, the minimum voltage of the output terminal E1 of the DC / DC converter 94 is set to 4.35V, which just meets the maximum voltage of 4.2V for the charging module 98 to fully charge the battery 93. Otherwise, the battery 93 cannot be fully charged to meet the 4.2V requirement.

[0193] If the voltage Ve1 at the output terminal E1 of the DC / DC converter 94 is adjusted to 4.8V, it is reduced by 0.7V through the isolation diode D1, and a voltage of 4.1V is obtained at the power supply terminal vd1 of the LTE module 95. Combined with the accuracy error of the internal feedback of the DC / DC converter 94 and the fluctuation of the voltage Ve1 at the output terminal E1, it is very likely to exceed the maximum operating voltage of 4.4V of the power supply terminal vd1 of the LTE module 95 in Table 2, causing damage to the LTE module 95. If the voltage Ve1 of the output terminal E1 of the DC / DC converter 94 is adjusted to 6V, a voltage of 5.3V is obtained at the power supply terminal vd1 of the LTE module 95. It is also necessary to add a BUCK power supply or a BUCK-BOOST power supply between the output terminal E1 of the DC / DC converter 94 and the power supply terminal vd1 of the LTE module 95 to meet the basic requirement of the 3.2-4.4V working voltage of the power supply terminal vd1 of the LTE module 95. The cost is greatly increased, and the layout density of the printed circuit board is also increased. At the same time, the dynamic response capability of the two-stage DC / DC converter is much lower than that of the single-stage DC / DC converter (for example Figure 11-12 The DC / DC converter solution shown in the figure) shows that the drop phenomenon of the power supply terminal vd1 of the LTE module 95 is more obvious. Another problem is that the charging module 98 between the output terminal E1 of the DC / DC converter 94 and the battery 93 adopts a low-cost linear charging solution. As long as the output voltage of the output terminal E1 of the DC / DC converter 94 exceeds 4.35V, it can meet the maximum charging voltage requirement of 4.2V of the battery 93. When the voltage Ve1 of the output terminal E1 of the DC / DC converter 94 exceeds 4.8V, the greater the voltage drop of the charging module 98 between the output terminal E1 of the DC / DC converter 94 and the battery 93, the greater the heat power consumption generated in the charging module 98, and heat dissipation is another troublesome problem.

[0194] In summary, the voltage Ve1 at the output terminal E1 of the DC / DC converter 94 is adjusted to 4.35V to 4.7V, which meets the requirement of the linear charging chip forming the charging module 98 for the maximum charging voltage of 4.2V for the battery 93. Figure 11-12 The DC / DC converter solution shown in the figure also meets the 3.2V to 4.4V operating voltage range of the LTE module. At the same time, the use of a linear charging chip to form the charging module 98 (or a linear charging module composed of discrete devices) is more cost-effective than the switching charging chip to form the charging module 98. Moreover, the linear charging chip to form the charging module 98 (or a linear charging module composed of discrete devices) will not generate high-frequency switching noise like the switching charging module when working, which will affect the performance of the GPS antenna and the LTE antenna, and will also affect the EMI radiation index, achieving multiple goals at one stroke.

[0195] Figure 2 to Figure 7In the scheme shown, an isolation diode D1 is inserted between the output terminal E1 of the DC / DC converter 94 and loads such as the LTE module 95, the low-dropout linear regulator (LDO) 99 and the GPS module 96, generating about 0.5V to 0.7V on the isolation diode D1. When a current of 1A passes through, the thermal power consumption is calculated to be about 0.5W to 0.7W. If a current of 1.5A passes through, the thermal power consumption is calculated to be about 0.75W to 1.05W. If a current of 2A passes through, the thermal power consumption is calculated to be about 1W to 1.4W, which affects the power supply efficiency of the entire machine. Due to the distributed resistance ESR and distributed inductance ESL on the isolation diode D1, when the load such as the LTE module 95 consumes a large current instantaneously, a very large voltage drop will be generated on the isolation diode D1. When the load such as the LTE module 95 is lightly loaded, there will be a smaller voltage drop. This will cause a very large voltage drop between the output terminal E1 of the DC / DC converter 94 and the loads such as the LTE module 95, the low-dropout linear regulator (LDO) 99 and the GPS module 96, resulting in a large drop problem when transmitted to each load.

[0196] The voltage at the output terminal E1 of the DC / DC converter 94 is 4.4V, minus a voltage drop of 0.5 to 0.7V, and the operating voltage range of the LTE module 95 is approximately 3.7V to 3.9V.

[0197] Based on the above problems, the following introduces a method for implementing the voltage drop problem and mutual interference problem caused by a single power supply system supplying power to multiple loads at the same time.

[0198] Fig. 9 A circuit diagram of a dual power supply system is given. Figure 2 to Figure 7 Comparison of the schemes shown, Fig. 9 In the solution, a transistor Q2 is connected in parallel at both ends of the isolation diode D1 between the output end E1 of the DC / DC converter 94 and the load (MOSFET, IGBT, thyristor, relay, etc. can also be connected in parallel without limitation) to reduce the voltage drop of the isolation diode D1, and reduce the load power failure and network disconnection caused by the large internal resistance of the isolation diode when multiple loads consume large currents in dynamic response. When the transistor Q2 is saturated and turned on, the voltage drop between the e pin and the c pin of the transistor Q2 is about 0.1V to 0.15V. After the transistor Q2 is connected in parallel with the isolation diode D1, the specific implementation method of calculating the voltage drop is described below.

[0199] Take the isolation diode D2 as a common silicon diode and the transistor Q1 as an example for explanation:

[0200] Taking the voltage drop (voltage difference) across the anode a and cathode k of the isolation diode D2 as a minimum of 0.5V, the voltage drop (voltage difference) across the c pin and e pin of the transistor Q1 as a minimum of 0.1V, and the output voltage of the output terminal E1 of the DC / DC converter 94 as 4.4V as an example, the voltage drop across the anode a and cathode k of the isolation diode D2 / the voltage drop across the c pin and e pin of the transistor can be calculated according to the calculation formula for the parallel connection of different voltage drops of the two devices (similar to solving the equivalent resistance of two resistors in parallel):

[0201]

[0202] Taking the voltage drop (voltage difference) across the anode a and cathode k of the isolation diode D2 as 0.7V at maximum and the voltage drop (voltage difference) across the c pin and e pin of the transistor Q2 as 0.15V as an example, the voltage drop across the anode a and cathode k of the isolation diode D2 / the voltage drop across the c pin and e pin of the transistor can be calculated according to the calculation formula for the parallel connection of different voltage drops of the two devices (similar to solving the equivalent resistance of two resistors in parallel):

[0203]

[0204] At this time, the voltage drop from the output terminal E1 of the DC / DC converter 94 to the common terminal E2 is approximately between 0.0833V and 0.1235V. The output voltage Ve1 of the output terminal E1 of the DC / DC converter 94 is 4.4V. After subtracting the voltage drop of 0.0833V to 0.1235V, the operating voltage range of the LTE module 95 is approximately 4.3167V to 4.2765V. Fig. 9 Program and Figure 2 to Figure 7 Comparison of the schemes in Fig. 9 The voltage drop ratio of the isolation diode D2 in parallel with the transistor Q1 is Figure 2 to Figure 7 The voltage drop of the isolation diode D2 is as small as 0.4167V~0.5765V, which greatly reduces the voltage drop and loss on the isolation diode D2.

[0205] because Fig. 9 The voltage drop ratio of the isolation diode D2 in parallel with the transistor Q2 is Figure 2 to Figure 7 The voltage drop of the isolation diode D2 in the circuit is as small as 0.4167V to 0.5765V, which greatly reduces the load-side power supply voltage (for example, Fig. 9 The LTE module 95) drops, causing load power outage and network disconnection.

[0206] Fig. 9 The transistor Q2 at both ends of the isolation diode D1 can also be used Figure 8The switch tube Q5 and the driving circuit (resistor R3, resistor R4, NMOS tube Q6, resistor R5, capacitor C9, resistor R6 constitute the driving circuit) are used to replace it, and the description is not repeated.

[0207] The following is a solution to improve the dynamic response of DC / DC converters and improve the voltage drop problem caused by multiple load power supply.

[0208] like Fig.12 The DC / DC converter 94 shown in the figure adopts a BUCK power supply topology structure. A feedforward capacitor C8 is connected in parallel across the resistor R1 in the sampling component 88. The feedforward capacitor C8 is used to increase the response speed of the feedback system of the DC / DC converter 94, thereby improving the dynamic response capability of the DC / DC converter 94 with load, reducing the output ripple, and greatly improving the load of multiple loads (for example Fig.12 The power supply of the LTE module 95, the low-dropout linear regulator (LDO) module 99 and the GPS module 96) produces a voltage drop problem.

[0209] A(s) is the open loop gain of the DC / DC converter 94 power system. For the convenience of discussion, we assume that A(s) already includes the first capacitor C1, the load (e.g. Fig.12 The influence of other factors such as LTE module 95, low voltage drop linear regulator LDO module 96, etc. Fig.12 The voltage V1 at the output terminal E1 of the DC / DC converter 94 when the feedforward capacitor C8 is not used is:

[0210]

[0211] Among them, β is the feedback coefficient. Its loop gain is:

[0212]

[0213] From the above, it can be obtained that: by adjusting the resistor R1 and the capacitor R2 in the sampling component 88, the voltage V1 at the output terminal E1 of the DC / DC converter 94 can be changed, but at the same time, the bandwidth of G(s) is also narrowed. Reasonable use of the feedforward capacitor C8 can improve the bandwidth and response speed of the power supply. At this time, the loop gain is: It can be obtained that the feedforward capacitor C8 does not change the voltage V1 at the output terminal E1 of the DC / DC converter 94, but introduces a pair of low-frequency zero fz and high-frequency pole fp to the feedback system. The zero point will increase the phase margin, and the pole will deteriorate the phase margin. Only by keeping the zero point and the pole as far away as possible can more phase margin be obtained. However, the distance between the zero-pole pair introduced by the feedforward capacitor C8 is fixed in the logarithmic coordinate, because:

[0214]

[0215] Based on this, it can be determined that the effect of the feedforward capacitor C8 is more obvious when R1 / R2 is larger, and it has no effect when R1 = 0. When R1 / R2 is determined, the feedforward capacitor C8 needs to be reasonably selected.

[0216] The following describes how to select the feedforward capacitor C8.

[0217] In order to take into account the bandwidth and phase margin of the system, the optimized capacitance of the feedforward capacitor C8 can be obtained by the following steps:

[0218] 1. Measure the system crossover frequency fc without feedforward capacitor C8;

[0219] 2. The zeros and poles introduced by the selected feedforward capacitor C8 satisfy:

[0220]

[0221] Simplified to:

[0222]

[0223] For example:

[0224] Fig.14 The loop gain curve of the DC / DC converter 94 feedback system measured without a feedforward capacitor is shown. The DC / DC converter 94 (using a BUCK power supply topology) is set to 5V, and resistors R1 = 105kΩ, R2 = 20kΩ are used, and β = 0.16. Using a loop analyzer, the loop gain curve of the system is measured without a feedforward capacitor, as shown in FIG. Fig.14 As shown, C is the phase curve and D is the gain curve. Fig.15 The load transient response diagram of the DC / DC converter without feedforward capacitor is given as follows: Fig.14 , Fig.15 As shown, the DC / DC converter 94 (BUCK power supply topology) without a feedforward capacitor is subjected to a load transient response test. When the load jumps from 1A to 3A, the voltage V1 at the output terminal E1 of the DC / DC converter 94 has a maximum voltage jump (that is, voltage drop) of 340mV.

[0225] Fig.16 A loop gain curve diagram of the DC / DC converter 94 feedback system measured with a feedforward capacitor is given, as shown in FIG. Fig.16 As shown in the figure, C is the phase curve and D is the gain curve. It can be seen from the figure that the cross-over frequency becomes 72.4kHz, the bandwidth is doubled, and at the same time, the phase margin is increased to 50°. Fig.17 The load transient response diagram of the DC / DC converter using a 110pF feedforward capacitor is shown. Fig.12 , Fig.17 As shown, the DC / DC converter 94 (BUCK power supply topology) with a feed-forward capacitor is subjected to the same load transient response test. After a 110pF feed-forward capacitor C8 is connected in parallel across the resistor R1, the maximum voltage jump (that is, voltage drop) of the voltage V1 at the output terminal E1 of the DC / DC converter 94 is reduced from 340mV to 200mV, which is a significant improvement.

[0226] In summary, the reasonable use of feedforward capacitor C8 can significantly improve the dynamic characteristics of the power supply. The optimal value of feedforward capacitor C8 is based on the optimal compromise between system bandwidth and phase margin. In actual application, the bandwidth and margin requirements of DC / DC converter 94 are appropriately increased or decreased to further optimize the bandwidth or margin.

[0227] The following is a method for solving the voltage drop problem and mutual interference problem caused by a single power supply system supplying power to multiple loads at the same time.

[0228] Fig. 9 A dual power supply circuit structure is given. Fig. 9 That's right Figure 2 to Figure 7 The power line from the cathode k of the isolation diode D2 to the common terminal E2, the power line from the cathode k of the isolation diode D1 to the common terminal E2, the power line from the common terminal E2 to the LTE module 95, and the power line from the common terminal E2 to the low-dropout linear regulator (LDO) module 99 and the GPS module 96 are marked. Fig.18 A cross-sectional view of a multi-load power supply system in the vertical direction of the PCB board is given. Fig.18 that is Figure 2 to Figure 7 A cross-sectional view of a power supply system for multiple loads in a vertical direction of a PCB board; Fig.19 Another cross-sectional view of another power supply system for multiple loads in the vertical direction of the PCB board is given; Fig.19 that is Figure 2 to Figure 7 Another power supply system for multiple loads is a cross-sectional view of the PCB board vertically;

[0229] Fig. 20 A top view of a PCB board of another power supply system for supplying power to multiple loads is given. Fig. 20 that is Figure 2 to Figure 7 A cross-sectional view of a power supply system for multiple loads in the vertical direction of the PCB board.

[0230] like Figure 2 to Figure 12 , Fig.18 As shown, Fig. 9The fourth capacitor C3 includes a large-capacity capacitor C31 (such as an aluminum electrolytic capacitor, a tantalum capacitor, a solid-state capacitor, a ceramic capacitor with a capacity of 1uF or more, a niobium capacitor, a super capacitor, etc.), and a high-frequency capacitor C30 (such as a ceramic capacitor with a capacity of 0.1uF or less). The large-capacity capacitor C31 is used for energy storage and discharge, and the high-frequency capacitor C30 is used to filter out the high-frequency noise generated by each load during high-speed flipping, to avoid mutual interference between the loads through the common power supply line 30 and the power supply line 33, and to avoid each load from conducting to the external power supply circuit through the power supply line 30, causing EMI radiation to exceed the standard or stray power to exceed the standard; the high-frequency capacitor C30 and the large-capacity capacitor C31 are arranged on the L1 layer (that is, the TOP layer) of the PCB board. The power supply line 30 is a power supply line from the cathode k of the isolation diode D2 to the common terminal E2, and the power supply line 31 is a power supply line from the cathode k of the isolation diode D1 to the common terminal E2. The power supply line 30 and the power supply line 31 are arranged on the L1 layer of the PCB board 59; the power supply line 30 and the power supply line 31 are connected at the common terminal E2, and the common terminal E2 is provided with a high-frequency capacitor C30 and a large-capacity capacitor C31, and the 1st foot of the high-frequency capacitor C30 and its pad and the 1st foot of the large-capacity capacitor C31 and the through-hole pad 58 are connected through the common terminal E2 where the power supply line 30 and the power supply line 31 are connected, and the 2nd foot of the high-frequency capacitor C30 and its pad are grounded G, and the 2nd foot of the large-capacity capacitor C31 and its pad are grounded G. Fig.10 The large-capacity capacitor C31 in the circuit is a plug-in capacitor (such as an aluminum electrolytic capacitor), and its pin 1 is a plug-in pin. A through-hole pad 58 (a plug-in pad) is set at the position of the large-capacity capacitor C31 on the PCB board 59, and the pin 1 of the large-capacity capacitor C31 is inserted into the through-hole pad 58, and the through-hole pad 58 runs through the L1 layer, L2 layer, L3 layer, and L4 layer of the PCB board 59. The power line 33 is led out from the L1 layer of the through-hole pad 58 of the large-capacity capacitor C31 on the PCB board 59, and one end of the power line 33 is connected to the common terminal E2 through the pin 1 of the large-capacity capacitor C31 and the through-hole pad 58. The other end of the power line 33 is connected to the large-capacity capacitor C50, the high-frequency capacitor C51, and the LTE module 95 of the L1 layer of the PCB board 59. Among them, the capacitance value less than 1uF is considered a high-frequency capacitor, and greater than or equal to 1uF is considered a low-frequency capacitor.

[0231] Large-capacitance capacitors: usually refer to capacitors with larger capacitance values, such as capacitors greater than or equal to 1 microfarad (1uF). These capacitors are often used in circuits for low-frequency applications, such as power filtering, energy storage, decoupling, etc. Small-capacitance capacitors: refer to capacitors with smaller capacitance values, less than 1 microfarad (1uF). These capacitors are more common in high-frequency applications because they have lower equivalent series resistance (ESR) and equivalent series inductance (ESL), which makes them less lossy in high-frequency signal transmission.

[0232] The power line 32 is led out from the through-hole pad 58 of the L4 layer, and one end of the power line 32 is connected to the common terminal E2 through the pin 1 of the large-capacity capacitor C31 and the through-hole pad 58. The other end of the power line 32 is connected to the pin 1 and pad of the large-capacity capacitor C40 of the L4 layer of the PCB board 59, the pin 1 and pad of the high-frequency capacitor C41, and the input end of the low-dropout linear regulator (LDO) module 99, and the power supply terminal vd2 of the GPS module 96 is connected to the output end of the low-dropout linear regulator (LDO) module 99.

[0233] The input end of the low-dropout linear regulator (LDO) module 99 on the L4 layer of the PCB board 59, pin 1 and the pad of the large-capacity capacitor C40, and pin 1 and the pad of the high-frequency capacitor C41 are all connected to the common end E2, pin 1 and the pad of the large-capacity capacitor C50 on the L1 layer of the PCB board 59, pin 1 and the pad of the high-frequency capacitor C51, the power terminal vd1 of the LTE module 95, the power line 30, and the power line 31 through pin 1 of the large-capacity capacitor C31 and the through-hole pad 58. Whether the battery 93 is used to supply power to the low-dropout linear regulator (LDO) module 99 and the GPS module 96 on the L4 layer of the PCB board 59, or the LTE module 95 on the L1 layer of the PCB board 59, the power line 30, the power line 33, the power line 33 of the L1 layer, and the power line 32 of the L4 layer of the PCB board 59 are all separated, and they are all connected together after passing through the 1st pin of the large-capacity capacitor C31 and the through-hole pad 58. Therefore, once the power supply of the LTE module 95 is flipped at high speed and consumes a large current, the large-capacity capacitor C50 and the high-frequency capacitor C51 will discharge to the LTE module 95, and the large-capacity capacitor C31 will discharge to the LTE module 95 through the power line 33 and the large-capacity capacitor C50, and at the same time, the large-capacity capacitor C31 will discharge to the LTE module 95 through the power line 32, the large-capacity capacitor C40, and the high-frequency capacitor C41. Although the large-capacity capacitor C31 supplies power to two loads at the same time, it has a large capacitance and stores a large amount of charge. Therefore, the voltage at both ends of the large-capacity capacitor C31 will not suddenly change (based on the principle that the voltage at both ends of the capacitor will not suddenly change). When the power supply of the LTE module 95 is flipped at high speed and consumes a large current, it will not be obviously transmitted to the GPS module 96 through the 1st foot of the large-capacity capacitor C31 and the through-hole pad 58, the power line 32 of the L4 layer, the large-capacity capacitor C40, the high-frequency capacitor C41, and the low-voltage difference linear regulator (LDO) module 99. Therefore, when the power supply of the LTE module 95 is flipped at high speed and consumes a large current, it will not affect the normal operation of the GPS module 96. In this way, the mutual interference problem and the instantaneous power failure problem caused by the drop caused by a single power supply system supplying power to multiple loads at the same time are solved.

[0234] Fig. 9The second capacitor C5 includes a large-capacity capacitor C50 (such as an aluminum electrolytic capacitor, a tantalum capacitor, a solid-state capacitor, a ceramic capacitor with a capacity of 1uF or more, a niobium capacitor, a super capacitor, etc.), and a high-frequency capacitor C51 (such as a ceramic capacitor with a capacity of 0.1uF or less). The large-capacity capacitor C50 is used to store and discharge energy for the LTE module 95, and the high-frequency capacitor C51 is used to filter out the high-frequency noise generated by the LTE module 95 during high-speed flipping, so as to avoid conduction to the external power supply circuit through the power supply line 33 and the power supply line 30, causing EMI radiation exceeding the standard or stray exceeding the standard;

[0235] Fig. 9 The capacitor C4 includes a large-capacity capacitor C40 (such as an aluminum electrolytic capacitor, a tantalum capacitor, a solid-state capacitor, a ceramic capacitor with a capacity of 1uF or more, a niobium capacitor, a super capacitor, etc.), and a high-frequency capacitor C41 (such as a ceramic capacitor with a capacity of 0.1uF or less). The large-capacity capacitor C40 is used to store and discharge energy for the low-voltage difference linear regulator (LDO) module 99 and the GPS module 96, while the high-frequency capacitor C41 is used to filter out the high-frequency noise generated by the high-speed flipping of the GPS module 96, which is transmitted to the external power supply circuit through the low-voltage difference linear regulator (LDO) module 99, the power line 32, and the power line 30, causing EMI radiation to exceed the standard or stray to exceed the standard. The large-capacity capacitor C40 and the high-frequency capacitor C41 are set on the L4 layer (that is, the BOTTOM layer) of the PCB board 59.

[0236] and Fig.18 Comparison, the difference is, Fig.19 The large-capacitance capacitor C31 is a chip capacitor (such as a chip aluminum electrolytic capacitor, a chip tantalum capacitor, a chip solid-state capacitor, a chip supercapacitor, etc.), and at least one power via 53 is set near pin 1 and the pad of the large-capacitance capacitor C31. The power via 53 is used to connect to the power line 32 of the L4 layer of the PCB board 59, pin 1 and the pad of the large-capacity capacitor C40, pin 1 and the pad of the high-frequency capacitor C41, and the input end of the low-voltage difference linear regulator (LDO), and the output end of the low-voltage difference linear regulator (LDO) is connected to the power terminal vd2 of the GPS module 96. Fig.19 The role of the large-capacity capacitor C31 and the nearby power via 53 is similar to Fig.18 Pin 1 of the medium-to-large capacity capacitor C31 and the through-hole pad 58 have the same function, but the implementation method is slightly different. Fig.19 The other parts of the solution have the same functions as Fig.18 Basically the same, no repetitive description is given.

[0237] Fig. 20 The bulk capacitor C31 in the circuit is also a plug-in capacitor (such as a plug-in aluminum electrolytic capacitor, a plug-in super capacitor, etc.). Fig.18 Compare, Fig. 20The power supply line 33, the large-capacity capacitor C50, the high-frequency capacitor C51, the LTE module 95, the power supply line 32, the large-capacity capacitor C40, the high-frequency capacitor C41, and the low-voltage difference linear regulator (LDO) module 99 in the scheme are all arranged on the L1 layer of the PCB board 59. The pin 1 and the pad of the large-capacity capacitor C50, the pin 1 and the pad of the high-frequency capacitor C51, and the power supply terminal vd1 of the LTE module 95 are connected to the pin 1 and the pad of the large-capacity capacitor C31, the cathode k of the isolation diode D2 to the power supply line 31, and the cathode k of the isolation diode D1 to the power supply line 30 through the power supply line 33. The pin 1 and the pad of the large-capacity capacitor C40, the pin 1 and the pad of the high-frequency capacitor C41, and the input end of the low-voltage difference linear regulator (LDO) module 99 are connected to the pin 1 and the pad of the large-capacity capacitor C31, the cathode k of the isolation diode D2 to the power supply line 31, and the cathode k of the isolation diode D1 to the power supply line 30 through the power supply line 32. The power line 33 is not directly connected to the power line 31, but is short-circuited through the pin 1 of the capacitor C31 and the pad position.

[0238] Pin 2 and pad of the large-capacity capacitor C50, and pin 2 and pad of the high-frequency capacitor C51 are connected to ground G through ground copper foil CH3, and at least one ground via 52 is set near pin 2 and pad of the large-capacity capacitor C50, and pin 2 and pad of the high-frequency capacitor C51. The ground copper foil CH3 should completely cover and connect pin 2 and pad of the large-capacity capacitor C50, pin 2 and pad of the high-frequency capacitor C51, and the ground via 52.

[0239] Pin 2 and a pad of the large-capacity capacitor C40, and pin 2 and a pad of the high-frequency capacitor C41 are connected to the ground G through the ground copper foil CH2, and at least one ground via 51 is set near pin 2 and a pad of the large-capacity capacitor C40, and pin 2 and a pad of the high-frequency capacitor C41. The ground copper foil CH2 should completely cover and connect pin 2 and a pad of the large-capacity capacitor C40, pin 2 and a pad of the high-frequency capacitor C41, and the ground via 51.

[0240] Pin 1 and pad, pin 2 and pad of the bulk capacitor C31 are connected to pin 1 and pad, pin 2 and pad of the high frequency capacitor C30 respectively, pin 2 and pad of the bulk capacitor C31 are connected to ground copper foil GH1 of L1 layer in PCB board 59, and ground copper foil GH1 of L1 layer in PCB board 59 is connected to ground copper foil GH2 of L1 layer in PCB board 59 through pin 2 and pad of the bulk capacitor C31. Ground copper foil GH4 is provided on L2 layer of PCB board 59.

[0241] The projections of the ground copper foil CH2 in the L1 layer, the 2nd pin and pad of the large-capacity capacitor C40, the 2nd pin and pad of the high-frequency capacitor C41, the ground via 51, the ground copper foil CH3 in the L1 layer, the 2nd pin and pad of the large-capacity capacitor C50, the 2nd pin and pad of the high-frequency capacitor C51, and the ground via 52 on the L4 layer of the PCB board 59 all fall within the ground copper foil GH4 area set on the L4 layer (BOTTOM layer) of the PCB board 59, and the ground vias 51 and 52 are connected to the ground copper foil GH4 of the L4 layer of the PCB board 59. In this way, although the ground copper foil CH3 in the L1 layer is disconnected from the ground copper foil CH2 in the L1 layer and the ground copper foil CH1 in the L1 layer, the ground copper foil CH3 in the L1 layer is connected to the ground copper foil GH4 of the L4 layer through the ground via 52, and the ground copper foil CH2 in the L1 layer is connected to the ground copper foil GH4 of the L4 layer through the ground via 51.

[0242] Fig. 20 The principle of the scheme in Fig.18 Basically the same, no repetitive description is given.

[0243] The relationship between the load current, the load dynamic flip speed, the capacitance of the large-capacity capacitor C31, ESR (series equivalent resistance), and ESL (series equivalent inductance) is as follows:

[0244] When an external power supply circuit or a battery power supply circuit supplies power to multiple loads, the greater the current consumption of multiple loads or a single load, the greater the capacitance requirement of the large-capacity capacitor C31, and the large-capacity capacitor C31 can respond to the large-current discharge requirement, so that the drop phenomenon at the common end E2 is less obvious, and the influence of this large-current load on another large-current load or a load that does not consume large current is smaller, and the probability of power failure and mutual conduction interference caused by the drop is also smaller. If it is recommended to use an aluminum electrolytic capacitor with a low ESR value (equivalent series resistance / impedance) of 1000uF or above, it is recommended to use an aluminum electrolytic capacitor with a low ESR value of 2200uF. The larger the capacitance of the aluminum electrolytic capacitor, the smaller the ESR. The greater the capacitance requirement of the large-capacity capacitor C31, the greater the discharge current of the load consuming large current jump, and the stronger the response capability. After years of testing, the data obtained: the jump current of 1A corresponds to the capacity of 100uF capacitor.

[0245] When the load operating frequency is higher, its response speed is faster when it is flipped at high speed, and the dynamic response speed of the power supply is getting higher and higher. Not only does the capacitance of the large-capacity capacitor C31 need not be too small, but the ESR and ESL of the large-capacity capacitor C31 are required to be as small as possible. In the low-frequency range of 1MHz and below, the jump current does not require the ESL of the large-capacity capacitor C31, but only requires the ESR of the large-capacity capacitor C31 to be small. At this time, the ESL of the large-capacity capacitor C31 has a negligible effect on the jump current in the low-frequency range of 1MHz and below. The ESR of capacitor C31 will affect the discharge speed of the jump current in the low-frequency range of 1MHz and below (that is, the response speed of the large-capacity capacitor C31); and for the jump current in the low-frequency range of 1MHz to 10MHz, the ESL and ESR of the large-capacity capacitor C31 will have an obstructive effect on the discharge speed of the jump current in the low-frequency range of 1MHz to 10MHz (that is, the response speed of the large-capacity capacitor C31). Therefore, it is not recommended to use aluminum electrolytic capacitors for jump currents in the low-frequency range of more than 1MHz, which exceeds the bandwidth range of aluminum electrolytic capacitors. Therefore, it is recommended that low-ESR and low-ESL tantalum capacitors, solid capacitors (such as solid aluminum capacitors, solid tantalum capacitors), and large-capacity ceramic capacitors be used for large-capacity capacitors C31. However, large-capacity capacitors can make ESR very small, for example, solid-state capacitors can be made to 5mΩ, but ESL cannot be made too small, so a large-capacity capacitor C31 is used in combination with a high-frequency capacitor C30 in the power supply system. The large-capacity capacitor C31 has a small ESR and a large capacitance to maintain the response speed to low-frequency and large currents when the load is flipped at high speed, while the high-frequency ripple current response speed is provided by the high-frequency capacitor C30 with a low ESL value (such as a small-capacitance ceramic capacitor made of X7R material, a small-capacitance ceramic capacitor made of NP0 material). Table 3 shows the characteristics of aluminum capacitors and ceramic capacitors.

[0246] Table 3

[0247]

[0248]

[0249] The following is an introduction to the integrity of the power supply system, EMI radiation and conduction, and capacitor selection.

[0250] Fig.21 A power supply system model of DC / DC converter, load and power supply is given. Fig.21 that is Fig.18The scheme uses a power supply system model in which a DC / DC converter 94 supplies power to an LTE module 95 through an isolation diode D1 as an example for explanation. The DC / DC converter 94 supplies power to the LTE module 95 through a relatively long power line (e.g., power line 30, power line 33) and an isolation diode D1. The DC / DC converter 94 is far away from the LTE module 95, and the DC / DC converter 94 cannot quickly provide instantaneous dynamic large current discharge to the power supply terminal vd1 of the LTE module 95. Because a large-capacity capacitor C31 (energy storage capacitor) is connected in parallel to the LTE module 95 on the PCB board 59, the Δi current required for instantaneous dynamic discharge is provided to the power supply terminal vd1 of the LTE module 95. In addition, it is recommended to connect one or two small-capacity, low-ESL (ESL is the crosstalk equivalent inductance, the distributed parameter of the capacitor), low-ESR (ESR is the crosstalk equivalent resistance, the distributed parameter of the capacitor) high-frequency capacitors C30 in parallel with the large-capacity capacitor C31 to provide a low-impedance path for high-frequency current and reduce power supply noise and ripple. BULK capacitors are generally aluminum capacitors, tantalum capacitors, solid capacitors, and large-value ceramic capacitors. High-frequency capacitors are generally ceramic capacitors, also known as sheet ceramic capacitors or sheet capacitors.

[0251] The power supply system of the LTE module 95 requires that the fluctuation of the voltage V1 be guaranteed to be within the allowable range. Power supply requirements: ideal voltage source V1, no matter how large the output current is, the power supply voltage V1 of the LTE module 95 remains unchanged. The actual DC / DC converter 94, power line 30, power line 33, etc. all have internal resistance. Therefore, when the LTE module 95 generates a current jump, a changing voltage will inevitably be generated on the internal resistance, which also manifests as corresponding fluctuations. After adding the large-capacity capacitor C31, the large-capacity capacitor C31 and the high-frequency capacitor C30 are similar to a power supply at the moment of discharge, but there are also impedances in the form of ESR (series equivalent resistance) and ESL (series equivalent inductance), which produce a voltage drop in the discharge impedance, causing fluctuations in the power supply of the LTE module 95. Fig.21 The Cai model of the power supply system of LTE module 95 is given. The large-capacity capacitor C31 model is mainly composed of series equivalent inductance ESL2 (series equivalent inductance is also called parasitic inductance), series equivalent resistance ESR2, and actual distributed capacitance value ESC2, while the high-frequency capacitor C30 is mainly composed of series equivalent inductance ESL3, series equivalent resistance ESR3, and actual distributed capacitance value ESR3.

[0252] The power supply system model of the LTE module 95 The power distribution system is mainly divided into five components: DC power supply (DC / DC converter 94), energy storage capacitor (large capacity capacitor C31), capacitor (high frequency capacitor C30), PCB plate capacitor (e.g. Fig.18 The power supply lines 30 and 33 in the circuit form a flat plate capacitor with the ground copper foil CH1).

[0253] The large-capacity capacitor C31 (energy storage capacitor) generally uses tantalum capacitors, solid-state capacitors, and large-capacity ceramic capacitors for medium and low frequency energy storage and filtering, and provides the Δi current required for instantaneous dynamic discharge for the LTE module 95. The high-frequency capacitor C30 can use a ceramic capacitor to supplement the fast flip current of the LTE module 95 and filter relatively high-frequency noise.

[0254] The operating current in the LTE module 95 is Δi, and the causes of the noise in the power supply system are analyzed as follows:

[0255] Δi=C·dV / dt≈C·△V / △t;

[0256] Wherein, △V=(Voh-Vol)·90%-(Voh-Vol)·10%=0.8(Voh-Vol);

[0257] △t is the rise time Tr of the LTE module 95 after flipping. C is the equivalent capacitance of the load of the LTE module 95. The dynamic power consumption of the LTE module 95 also includes the power consumption caused by the flip crossover current of the LTE module 95, the flip current of the LTE module 95, etc. These instantaneous currents are prone to cause power supply noise, and the noise generated by the power supply system will cause the conduction and / or radiation indicators of the product EMI to exceed the standard.

[0258] The purpose of power supply filtering of LTE module 95 is to ensure that the voltage fluctuation of the device is small enough in the entire operating frequency range. The realization idea of ​​power supply filtering is to provide a sufficiently low loop impedance for the power supply of LTE module 95, so the unique impedance characteristics of capacitors can be used to achieve this purpose.

[0259] Because the power supply paths when the power supply jumps instantly are:

[0260] PCB flat capacitor (power line 30, power line 33 and ground copper foil CH1 form a flat capacitor 60) → high-frequency capacitor C30 → large-capacity capacitor C31 → LTE module 95

[0261] In the above system, the energy for the LTE module 95 to flip is provided by the flat capacitor 60 between the power supply and the ground plane.

[0262] The following introduces the selection considerations of the large-capacity capacitor C31 in the LTE module 95:

[0263] For the selection of input capacitor C11, tantalum capacitors, large-capacity ceramic capacitors, and solid-state capacitors are generally used. Taking tantalum capacitors as an example, tantalum capacitors are limited by process structure and materials; their CV value (capacitance multiplied by voltage) cannot be large, and the capacity and voltage have a certain range, generally from 0.1μF to 1000μF; the working voltage is 2V to 50V, and the capacity decreases with the increase of frequency. Because it is a solid MnO2 electrolyte, its capacity and temperature characteristics are relatively stable. The temperature characteristics of ESR are relatively stable. From room temperature 25℃ to low temperature -25℃ or below, ESR increases by about 1 to 2 times. The maximum ESR value of 100Hz given by the manufacturer can be used as a reference for design. The actual value is generally much smaller than the maximum value. The ESL of tantalum capacitors is generally around 2nH under good wiring conditions; tantalum capacitors are generally used for medium and low frequency filtering, not exceeding 10MHz, mainly hundreds of kHz to several MHz. Fig. 22 The impedance characteristic curve of tantalum capacitor is given, and its impedance frequency characteristic curve is generally U-shaped. Fig. 22 The impedance frequency characteristic curve of 150μF tantalum capacitor is shown to be "U" shaped, and the working bandwidth range of the resonance point is relatively large. Fig. 22 It can be seen that the impedance Z of a 150μF tantalum capacitor is 30.5mΩ between 100kHz and 2MHz, the ESR is about 60mΩ to 70mΩ between 100kHz and 2.5MHz, the lowest ESR can reach 28.6mΩ, and the ESL is about 2.4nH.

[0264] The operating frequency of LTE module 95 is relatively high, with the main frequency ranging from 700MHz to 2.7GHz, which is just within the operating bandwidth range of tantalum capacitors from several kHz to hundreds of kHz.

[0265] The following introduces the selection considerations of the high-frequency capacitor C30 at the LTE module 95 power supply end:

[0266] The high-frequency capacitor C30 generally adopts ceramic capacitors (MLCC, Multi-layer Ceramic Capacitors, chip multilayer ceramic capacitors) or BDL capacitors. Table 3 gives the various characteristics of ceramic capacitors in detail.

[0267] Please refer to Fig. 22 An ideal capacitor has zero dielectric loss, no leakage, zero distributed inductance, consistent frequency characteristics, and can output current that tends to infinity, so it can be fully charged when the current tends to zero. However, an ideal capacitor does not exist. The actual capacitor consists of equivalent series resistance (ESR) R11, equivalent series inductance (ESL) L11, and capacitor C11. The reason for this is the production process and the size of the package, such as the parasitic inductance generated by the pin lead (that is, the series equivalent inductance ESL). Since all substances are not superconductors, there is impedance.

[0268] Ceramic capacitors have a small ESR and have a V-shape with an obvious downward tip at the resonant frequency. In the 0402 package, the impedance of a 0.1uF ceramic capacitor is lower than that of a 0.01uF capacitor in all frequency bands. Figure 23-Figure 29 They are impedance-frequency curves of ceramic capacitors with different capacitance values. The impedance-frequency characteristic curve of ceramic capacitors is V-shaped. Fig.23 The impedance frequency curve of a 10pF ceramic capacitor is given. The lowest point of the impedance frequency curve represents the self-resonance frequency. The self-resonance frequency of a 10pF ceramic capacitor is about 2.8GHz, and the impedance at the self-resonance frequency is 400mΩ, at which point the impedance is minimum. Before the self-resonance point, the capacitor is capacitive, and beyond the self-resonance point, the capacitor gradually becomes inductive. Fig.24 The impedance frequency curve of a 30pF ceramic capacitor is given. The self-resonance frequency of the 30pF ceramic capacitor is about 1.67GHz, and the impedance at the self-resonance frequency is 89mΩ, at which point the impedance is minimum. Before the self-resonance point, it is capacitive, and beyond the self-resonance point, the capacitor gradually becomes inductive. Fig.25 The impedance frequency curve of a 100pF ceramic capacitor is given. The self-resonance frequency of the 100pF ceramic capacitor is about 1.25GHz, and the impedance at the self-resonance frequency is 89mΩ, at which point the impedance is minimum. Before the self-resonance point, it is capacitive, and beyond the self-resonance point, the capacitor gradually becomes inductive. Fig.26 The impedance frequency curve of a 1nF ceramic capacitor is given. The self-resonance frequency of a 1nF ceramic capacitor is about 420MHz, and the impedance at the self-resonance frequency is 280mΩ, at which point the impedance is minimum. Before the self-resonance point, the capacitor is capacitive, and beyond the self-resonance point, the capacitor gradually becomes inductive. Fig. 27 The impedance frequency curve of a 10nF ceramic capacitor is given. The self-resonance frequency of the 10nF ceramic capacitor is about 85MHz, and the impedance at the self-resonance frequency is 15mΩ, at which point the impedance is minimum. Before the self-resonance point, it is capacitive, and beyond the self-resonance point, the capacitor gradually becomes inductive. Fig.28 The impedance frequency curve of a 100nF ceramic capacitor is given. The self-resonance frequency of the 100nF ceramic capacitor is about 38MHz, and the impedance at the self-resonance frequency is 34mΩ, at which point the impedance is minimum. Before the self-resonance point, it is capacitive, and beyond the self-resonance point, the capacitor gradually becomes inductive. Fig.29 The impedance frequency curve of 1uF ceramic capacitor is given. The self-resonance frequency of 1uF ceramic capacitor is about 13MHz, and the impedance at the self-resonance frequency is 15mΩ, which is the minimum impedance; before the self-resonance point, it is capacitive, and after the self-resonance point, the capacitor gradually becomes inductive. Among them, the impedance of the ceramic capacitor is the smallest at the self-resonance point, and it shows the characteristics of resistance at this time. Its absorption effect is the best at the self-resonance point.

[0269] by Fig. 20 Taking PCB as an example, the power supply line 30, the power supply line 33 and the ground copper foil GH1 form a PCB flat plate capacitor.

[0270] Continue reading Fig. 20 , for example, the power supply lines 30 and 33 are arranged on the L1 layer of the PCB board 59, and the ground copper foil GH1 is arranged on the L2 layer. The power supply lines 30 and 33 form a PCB flat capacitor with the ground copper foil GH1. The ESL of the PCB flat capacitor is very small and can filter out noise up to GHz, so as to reduce the noise radiation generated by the power supply lines 30 and 33, which is easy to interfere with the radio frequency signal and antenna in the board, and at the same time reduce the external EMI radiation and conduction index and radio frequency stray index. For example, the power supply lines 30 and 33 form a PCB flat capacitor 60, ESL4 is the series equivalent inductance of the PCB flat capacitor 60, and ESR4 is the series equivalent resistance of the PCB flat capacitor 60. Between the ground copper foil GH1 of the second layer of the PCB board 59 and the power supply lines 30 and 33 of the L1 layer is PP (prepreg, a sheet-shaped bonding material synthesized by resin and carrier, that is, glass fiber epoxy resin material, referred to as FR-4 medium), and the dielectric constant of FR-4 medium is 3.5 to 4.5. The flat plate capacitor 60 is formed between the ground copper foil GH1 of the second layer of the PCB board 59 and the power lines 30 and 33 of the L1 layer. The calculation formula of the PCB flat plate capacitor 60 is as follows:

[0271] C = ε × ε0 × S / d;

[0272] Wherein: the plate capacitor C, unit is F; ε is the PP (prepreg, a sheet-like adhesive material synthesized from resin and carrier, that is, glass fiber epoxy resin material, referred to as FR-4 medium) dielectric constant between the power copper foil 42 of the second layer of the PCB board 59 and the ground copper foil G1 of the L1 layer in the PCB board 59, and the dielectric constant of the FR-4 medium is usually 3.5 to 4.5;

[0273] ε0 is the dielectric constant of vacuum: 8.86×10-12F / m;

[0274] S is the area, that is, the overlapping area between the power copper foil 42 of the second layer of the PCB board 59 and the ground copper foil G1 of the L1 layer. Since the projection of the power copper foil 42 of the second layer on the L1 layer is required to fall within the range of the ground copper foil G1 of the L1 layer, it is only necessary to calculate the area of ​​the power copper foil 42 of the second layer.

[0275] d is the distance between the plates, that is, the distance between the power copper foil 42 of the second layer and the ground copper foil GH1 of the L1 layer. The unit of the distance between the plates is m.

[0276] The following is a test process of the power supply system of the embodiment of the present invention:

[0277] In order to prove the rationality and practicality of the design of the power supply system provided in the embodiment of the present invention, taking the application of the power supply circuit in a wireless vehicle tracker as an example, the following tests were performed on the DC / DC converter output voltage: power supply output voltage test, power supply output voltage ripple test, and EMI radiation test.

[0278] For power supply output voltage test, Fig.30 The output voltage waveform of the DC / DC module is given when the load current is 2A;

[0279] Test conditions: wireless vehicle tracker, oscilloscope TDS2012C (sampling frequency 2GS / s, bandwidth 100MHz), digital control power supply.

[0280] like Fig.30 As shown, the DC / DC module 94 in the wireless vehicle tracker uses a BUCK chip, sets the input voltage to 12V, and sets the output voltage Ve1 to 4.4V. The digital control power supply provides an external 12V power supply to the DC / DC module 94 in the wireless vehicle tracker. When the DC / DC module 94 outputs a load current of 2A, the output voltage Ve1 of the power supply terminal vd1 of the LTE module 95 is measured by an oscilloscope and a probe to be a maximum value of 4.52V and a minimum value of 4.20V, which meets the design specification requirements.

[0281] For power supply output voltage ripple test, Fig.31 The figure shows the ripple of the power supply voltage at the common terminal E2 of the LTE module when the DC / DC module supplies power to the LTE module and the LTE module is in GPRS mode and at maximum power CAT1 B1.

[0282] Test conditions: wireless vehicle tracker, oscilloscope (sampling frequency 2GS / s, bandwidth 100MHz), digital control power supply.

[0283] The DC / DC module 94 in the wireless vehicle tracker uses a BUCK chip, sets the input voltage to 12V, and sets the output voltage Ve1 to 4.4V. The digital control power supply provides an external 12V power supply to the DC / DC module 94 in the wireless vehicle tracker.

[0284] like Fig.31 As shown, the LTE module is in GPRS maximum power CAT1 B1 mode. Fig. 9 The power supply circuit shown in the figure is tested to have a maximum voltage of 4.08V, a minimum voltage of 3.96V, an average voltage of 4.02V, a maximum ripple voltage of about 200mV, and a minimum ripple voltage of about 120mV at the common terminal E2.

[0285] Table 4 shows the ripple of the power supply voltage at the common terminal E2 of the LTE module when the DC / DC module supplies power to the LTE module under the condition of maximum power CAT1 B1 in the GPRS mode.

[0286] Table 4

[0287]

[0288] Table 5 shows the power supply voltage ripple of the common terminal E2 of the LTE module when the LTE module is powered by a 3.5-3.7V battery and the LTE module is in GPRS mode and at maximum power CAT1 B1.

[0289] Table 5

[0290] LTE B34 (TDD mode) 220mV 20.29dB LTE B38 (TDD mode) 220mV 18.98dB LTE B39 (TDD mode) 220mV 19.26dB LTE B40 (TDD mode) 220mV 19.94dB LTE B41 (TDD mode) 220mV 18.3dB LTE B1 (FDD mode) 160mV 20.13dB LTE B3 (FDD mode) 160mV 18.82dB LTE B5 (FDD mode) 200mV 20.96dB LTE B8 (FDD mode) 200mV 20.42dB

[0291] For EMI radiation testing, the radiation values ​​of the wireless vehicle equipment in the 30MHz to 1GHz test frequency band are given for illustration. Both the RE radiation test standard and the CE conducted emission test standard adopt the EN55022-2008 / GB9254-2008 standard, and the wireless vehicle equipment is tested in the 0.15MHz to 0.5MHz / 0.5MHz to 30MHz / 30MHz to 1GHz / 1GHz to 6GHz frequency bands. These frequency bands all meet the Class B test requirements in the EN55022-2008 / GB9254-2008 standard. Fig.32 The radiation value emitted by the driving recorder in the test frequency band of 30MHz to 1GHz is given. Fig.32 A refers to the safety limit of the 3C standard. If it is lower than this safety limit, it is qualified; B refers to the fluctuation curve of the radiation data of the tested product. Fig.32 It can be seen that line B is far away from line A and there is a large margin, which is much smaller than the safety standard value, indicating that the EMI radiation of the wireless vehicle-mounted equipment is well controlled.

[0292] The following describes the power supply requirements for typical LTE modules.

[0293] Table 6 shows the characteristics of a certain type of LTE module power supply. From Table 1, it can be seen that the minimum operating voltage of the LTE module is 3.2V, the typical value is 3.8V, and the maximum value is 4.4V; the maximum instantaneous drop of the LTE module under the maximum RF output condition is 0.4V (400mV); the maximum value of the data transmission current is 589mA in EGSM900 1D / 4U PCL=5 mode, 541mA in WCDMAB1 HSDPA 541 mode, and 710mA in LTE B3 mode; in LTE DRX=5 mode, the maximum value of the standby current is 5.5μA; the instantaneous current of RF transmission reaches 3A.

[0294] Table 6

[0295]

[0296] Table 7 gives the basic requirements of a certain type of LTE module power pin for power supply. Fig.33 A schematic diagram of the power supply system for a certain type of LTE module is given. From Table 7, Fig.33 It can be seen that the power terminal vd1 of the LTE module 95 includes two sets of power pins: a baseband power pin VBAT_BB and a radio frequency power pin VBAT_RF. Figures 1 to 8 , Figures 9 to 12 The second capacitor C5 in the embodiment actually includes: ① a large-capacity capacitor C10 (a 100μF low ESR capacitor), a high-frequency capacitor C11 (a 0.1μF chip ceramic capacitor), a high-frequency capacitor C12 (a 33pF chip ceramic capacitor), and a high-frequency capacitor C13 (a 10pF chip ceramic capacitor) set at the baseband power supply pin VBAT_BB; ② a large-capacity capacitor C20 (a 100μF low ESR capacitor), a high-frequency capacitor C21 (a 0.1μF chip ceramic capacitor), a high-frequency capacitor C22 (a 33pF chip ceramic capacitor), and a high-frequency capacitor C23 (a 10pF chip ceramic capacitor) set at the RF power supply pin VBAT_RF to meet the basic power supply requirements of the LTE module 95 shown in Table 7.

[0297] Table 7

[0298]

[0299] Fig.34 The waveform diagram of the hopping cycle change of the LTE module 95 is given. When the LTE module 95 is transmitting at maximum, there is a burst pulse of 1 / 8 TDMA cycle (lasting 577μs) every 4.615ms. Fig.34As shown, during the burst pulse (drop) stage, the power supply must be able to provide a sufficiently high peak current to ensure that the power supply voltage provided to the power supply terminal vd1 of the LTE module 95 does not drop to the minimum operating voltage of the LTE module 95. For example, Table 7 gives the minimum operating voltage of a certain model of LTE module 95 as 3.2V. At the maximum transmission power level of the LTE module 95, the peak current of the RF power pin VBAT_RF (the power terminal vd1 of the LTE module 95 includes the RF power pin VBAT_RF and the baseband power pin VBAT_BB) in the LTE module 95 will reach about 2A, and the peak current of the baseband power pin VBAT_BB (the power terminal vd1 of the LTE module 95 includes the RF power pin VBAT_RF and the baseband power pin VBAT_BB) in the LTE module 95 will reach about 1A. The peak currents of the two groups of power pins combined can reach about 3A, which will cause the power supply voltage of the RF power pin VBAT_RF and the baseband power pin VBAT_BB in the LTE module 95 to drop. For example, if the power supply voltage drops below 3.2V, the system will reset, shut down or restart. To ensure that the LTE module 95 can work stably and normally, the drop voltage of the RF power pin VBAT_RF and the baseband power pin VBAT_BB in the LTE module 95 should not exceed 400mV.

[0300] The pulse width of the jump is calculated according to the jump period variation waveform of the LTE module 95.

[0301] from Fig.34 It is known that the pulse width of the LTE module 95 at the maximum transmission power is about 577μs. The conversion formula based on the period T and frequency f is as follows:

[0302] T = 1 / f;

[0303] Then f = 1 / T = 1 / 577μs = 1 / 577x10-6s = 1.733kHz;

[0304] When the LTE module 95 is at the maximum transmission power, the pulse width of the jump is about 577μs, and the corresponding drop pulse interference frequency band is 1.733kHz.

[0305] And for Figures 1 to 8 , Figures 9 to 12 The DC / DC converter in the scheme shown in the figure, if the BUCK, BOOST, BUCK-BOOST power supply scheme is adopted, the BUCK power supply generally works at tens of kHz to several MHz, and the BUCK power supply is combined with the internal output capacitor and then with Figures 1 to 8 , Figures 9 to 12The PCB stacking and layout scheme shown (the power supply scheme for the LTE module 95 and the GPS module 96 needs to be separated from pin 1 of the first capacitor C1), the BUCK, BOOST, and BUCK-BOOST power supply schemes are fully capable of suppressing the interference caused by the 1.733kHz drop pulse generated by the LTE module 95.

[0306] At the maximum transmission power of LTE module 95, the pulse width of the jump is about 4.615ms, and the corresponding drop pulse interference frequency band is 21.6kHz. Figure 23-Figure 29 The impedance frequency curve of ceramic capacitors with different capacitance values ​​shows that all the ceramic capacitors with different capacitance values ​​are within their bandwidth range. Therefore, ceramic capacitors cannot filter out low-frequency drop pulse interference.

[0307] Fig. 22 This is the impedance frequency curve of 150μF tantalum capacitor. Please refer to Fig. 22 , the impedance frequency characteristic curve of 150μF tantalum capacitor is "U" shaped, and the working bandwidth range of the resonance point is relatively large. As can be seen from the figure, its impedance is 30.5mΩ between 100kHz and 1MHz, and its ESR is about 60mΩ~70mΩ between 10kHz and 10MHz. The lowest ESR can reach 28.6mΩ, and the ESL is about 2.4nH. In the 1.733kHz frequency band, the impedance of 150μF tantalum capacitor is about 1Ω, and the ESR is about 70mΩ. That is, 150μF tantalum capacitor is used in Fig.33 C10 and C20 in the circuit will effectively suppress the drop pulse interference generated by the 1.733kHz frequency band of the LTE module 95.

[0308] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A power supply system, characterized in that: include: Interface and external power supply circuit; The external power supply circuit includes a converter, a first capacitor and at least two first power supply sub-circuits; The interface is used for external power supply; the interface is also connected to the input end of the converter; the anode of the first unidirectional conductive switch included in each first power supply subcircuit is connected to the output end of the converter through a power line; the cathode of each first unidirectional conductive switch is connected to the power supply end through a power line; the power supply end is used to connect at least two loads; The output end of the converter is also connected to one end of the first capacitor through a power line, and the other end of the first capacitor is grounded.

2. The power supply system according to claim 1, characterized in that: The power supply system further includes a second capacitor; one end of the second capacitor is connected to the power supply end, and the other end of the second capacitor is grounded.

3. The power supply system according to claim 1, characterized in that: The external power supply circuit also includes: An external power clamp filter module; the input end of the converter is connected to the interface through the external power clamp filter module; and / or, an inductor; one end of the first capacitor is connected to the output end of the converter through the inductor; And / or, a sampling component; the sampling component comprises a first resistor, a second resistor and a feedforward capacitor, one end of the first resistor is connected to one end of the second capacitor, the other end of the first resistor is respectively connected to one end of the second resistor and a feedback pin of a DC / DC converter chip included in the converter, and the other end of the second resistor is grounded; the feedforward capacitor is connected in parallel with the first resistor; And / or, a first switch tube; the anode of each first unidirectional conductive switch is connected to the input end of a first switch tube, and the cathode is connected to the output end of the first switch tube; the control end of the first switch tube is connected to at least one load.

4. The power supply system according to any one of claims 1 to 3, characterized in that: The power supply system also includes a battery power supply circuit, which includes a battery and a second power supply circuit, wherein the output end of the battery is respectively connected to the input end of the second power supply circuit, and the output end of the second power supply circuit is connected to the power supply end.

5. The power supply system according to claim 4, characterized in that: The second power supply subcircuit comprises: A second unidirectional conductive switch; an anode of the second unidirectional conductive switch is connected to the input end of the second power supply circuit, and a cathode of the second unidirectional conductive switch is connected to the output end of the second power supply circuit.

6. The power supply system according to claim 5, characterized in that: The battery powered circuit further comprises: A third capacitor; the battery is connected to the input end of each second power supply electronic circuit through one end of the third capacitor, and the other end of the third capacitor is grounded; And / or, a fourth capacitor, one end of the fourth capacitor is connected to the power supply end, and the other end of the fourth capacitor is grounded.

7. The power supply system according to claim 6, characterized in that: The fourth capacitor includes a large-capacity capacitor and / or a high-frequency capacitor connected in parallel; the capacitance value of the large-capacity capacitor is greater than or equal to 1uF, and the capacitance value of the high-frequency capacitor is less than 1uF.

8. The power supply system according to claim 6, characterized in that: The power supply system is integrated on a PCB board, the PCB board is provided with a through-hole pad penetrating through each layer of the PCB board, the fourth capacitor is deployed on the top layer of the PCB board, and the pin of the fourth capacitor is inserted into the through-hole pad; the through-hole pad serves as the power supply end; Leading out a first power line from the through-hole pad on the top layer, the first power line also being connected to the cathode of the first unidirectional conductive switch; and / or, second power lines are led out from the through-hole pads on the top layer, and each second power line is connected to a first load; and / or, a third power line is led out from the through-hole pad on the top layer, and the third power line is also connected to the cathode of the second unidirectional conductive switch; And / or, a fourth power line is led out from the through-hole pad on the bottom layer of the PCB board, and each third power line is connected to a second load.

9. The power supply system according to claim 4, characterized in that: The power supply system further includes a charging module, wherein an output end of the charging module is connected to a charging end of the battery, and an input end of the charging module is connected to one end of the first capacitor; And / or, the charging module is connected to at least one load; The load is used to determine whether the output voltage of the battery is within a preset range, and send a charging instruction to the charging module if the output voltage is within a preset range; The charging module is used to start up when receiving a charging instruction sent by the load to charge the battery; And / or, the power supply system also includes a processor, which is electrically connected to the charging module, and the processor is used to determine whether the output voltage of the battery is within a preset range, and send a charging instruction to the charging module when the judgment is no.

10. The power supply system according to claim 4, characterized in that: The capacitance value of the first capacitor is determined according to at least one of the following: the switching frequency of the converter, the working current of the load, and the ripple current; And / or, the impedance characteristic curve of the first capacitor matches the switching frequency of the converter.

11. The power supply system according to claim 5, characterized in that: The second power supply subcircuit also includes: a second switch tube; the anode of each second unidirectional conductive switch is connected to the input end of a second switch tube, the cathode is connected to the output end of the second switch tube, and the control end of the second switch tube is connected to at least one load.

12. The power supply system according to claim 11, characterized in that: The load includes an LTE module and a GPS module; the power supply system also includes a normally closed low-voltage dropout linear regulator, and the output end of the first power supply electronic circuit and the output end of the first power supply electronic circuit are connected to the GPS module through the low-voltage dropout linear regulator; The LTE module is also in communication connection with the low-dropout linear regulator, and the LTE module is used to send an activation signal to the low-dropout linear regulator to activate the low-dropout linear regulator to supply power to the GPS module; And / or, the power supply system also includes a processor, which is electrically connected to the low-voltage difference linear regulator, and the processor is used to send an enable signal to the low-voltage difference linear regulator to turn on the low-voltage difference linear regulator to power the GPS module.

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