Power supply diagnosis circuit and power supply circuit of external active antenna

Abstract

The utility model relates to the technical field of vehicle-mounted power supply, and discloses a power supply diagnosis circuit and a power supply circuit with an external active antenna, and the power supply diagnosis circuit comprises a low-dropout voltage stabilizer which is used for supplying power to a load through voltage conversion, monitoring an output current, and determining a level state of a state error reporting pin according to a current monitoring result; a first pin of the first enabling module is connected with an enabling pin of the low-dropout voltage stabilizer, a second pin of the first enabling module is connected with a state error reporting pin of the low-dropout voltage stabilizer, and the first enabling module is used for adjusting the level state of the enabling pin according to the level state of the state error reporting pin, so that the low-dropout voltage stabilizer conducts or cuts off power supply to the load according to the level state. According to the low-dropout voltage stabilizer, the working characteristics of the low-dropout voltage stabilizer are matched with an external self-built circuit, so that load state judgment can be realized through current monitoring, the condition of voltage intersection is avoided, the accuracy of load state judgment is improved, an abnormal state can be quickly responded, and a circuit which is turned off in case of overcurrent is realized.

Description

Technical Field

[0001] This utility model relates to the field of vehicle power supply technology, specifically to a power supply diagnostic circuit and a power supply circuit for an external active antenna. Background Technology

[0002] Current vehicle-mounted telematics boxes (TBOX) typically integrate GNSS modules to provide navigation or timing services for the vehicle. However, the radio frequency signal strength from satellites is relatively weak. Therefore, an external active antenna is required at the TBOX to amplify the signal, and the power supply for the active antenna is provided by the TBOX. Additionally, the antenna's operating status needs to be diagnosed at the TBOX: normal operation, short circuit (short to ground), or open circuit.

[0003] In existing technology, a switching chip controls the TBOX to turn on and off the power supply to the external active antenna. Therefore, voltage diagnostics are performed on the circuit connected to the switching chip and the external active antenna. When the antenna is open-circuited, no power supply is needed, and the diagnostic voltage is close to the antenna's supply voltage. When the antenna is short-circuited (short-to-ground), the diagnostic voltage is close to 0V. Theoretically, when the antenna is working normally, the diagnostic voltage should be between open-circuit and short-circuit voltages. The MCU uses this diagnostic voltage to determine the antenna's state. If a short-circuit fault occurs, the MCU turns off the switching chip via an enable signal, thus cutting off power to the antenna and preventing high current damage to the internal components of the active antenna or the TBOX board circuitry. However, in actual operation, the range of the diagnostic voltage when the antenna is open-circuited overlaps with that during normal operation, making it impossible to accurately define the antenna's state and posing a risk of misjudging the antenna's state. Furthermore, there is a delay between the MCU reading the antenna's short-circuit state and turning off the switching chip, which could potentially damage the circuit due to high current. Utility Model Content

[0004] In view of this, the present invention provides a power supply diagnostic circuit to solve the problem that the MCU shutdown switch chip has a delay, which causes it to be unable to shut off the power supply to the external active antenna in a timely manner.

[0005] In a first aspect, this utility model provides a power supply diagnostic circuit, including:

[0006] The low dropout voltage regulator has an input pin connected to the power supply and an output pin connected to the load. It is used to convert the power supply from a first voltage to a second voltage to power the load, and to monitor the output current of the output pin. Based on the current monitoring result, it determines the level state of the status error pin.

[0007] The first enable module has a first pin connected to the enable pin of the low dropout regulator and a second pin connected to the status error reporting pin of the low dropout regulator. It is used to adjust the second level state of the enable pin according to the first level state of the status error reporting pin, so that the low dropout regulator turns on or off the power supply to the load according to the second level state.

[0008] The power supply diagnostic circuit provided by this utility model converts the power supply voltage through a low-dropout regulator and determines the level state of the status error pin by monitoring the output current of the output pin. The enable module adjusts the level state of the enable pin according to the level state of the low-dropout regulator's status error pin, so that the low-dropout regulator turns on or off the power supply to the load according to the level state of the enable pin. This utility model, through the working characteristics of the low-dropout regulator itself and the cooperation of external self-built circuits, can provide a relatively stable voltage to the load. It can judge the load status by current monitoring, avoid voltage overlap, improve the accuracy of load status judgment, and can quickly respond to abnormal conditions, realizing the circuit function of overcurrent shutdown, providing instantaneous protection for the load circuit and preventing damage due to excessive current when the load is short-circuited.

[0009] In one optional implementation, the power supply diagnostic circuit further includes: a second enable module, wherein the first pin of the second enable module is connected to the output current monitoring pin of the low dropout regulator, and the second pin is connected to the first pin of the enable module, for determining the third level state input to the enable pin based on the monitoring voltage output by the output current monitoring pin after the low dropout regulator determines the monitoring voltage based on the current monitoring result.

[0010] By deploying a second enabling module, this utility model can cooperate with the first enabling module. When the first enabling module quickly disconnects the power supply to the load, it promptly disables the low-dropout regulator, keeping the low-dropout regulator in a power-off state to the load and preventing the enable pin of the low-dropout regulator from being in a state of repeated switching oscillation.

[0011] In one optional implementation, the first enable module includes: a first transistor, with its first pin connected to a status error pin and its second pin connected to an external pull-up source; a first resistor, with its first pin connected to the first pin of the first transistor and its second pin connected to the second pin of the first transistor; a second resistor, with its first pin connected to the third pin of the first transistor and its second pin connected to the first pin of the second transistor; the second pin of the second transistor connected to the first pin of the third resistor and its third pin connected to ground; a fourth resistor, with its first pin connected to the first pin of the second transistor and its second pin connected to ground; the second pin of the third resistor and the first pin of the fifth resistor connected to the enable pin, and connected to the first pin of the seventh resistor; the second pin of the fifth resistor connected to ground; and the second pin of the sixth resistor connected to the second pin of the second enable module. This invention uses a transistor and a resistor to form a first enable module. When the low-dropout regulator detects an abnormal current at the output pin, it can promptly pull down the level of the enable pin through the circuit structure, thereby realizing the power supply diagnosis function of overcurrent shutdown. This allows the low-dropout regulator to shut down its output in a timely manner, protecting the circuit from damage caused by short-circuit faults.

[0012] In one alternative implementation, the first transistor is a PNP transistor and the second transistor is an NPN transistor.

[0013] This invention utilizes transistors to cut off or turn on the circuit based on the high or low voltage level of the pins, thereby enabling control of the low dropout regulator's enable pin in the circuit structure. This results in a rapid response and prevents damage to the circuit during short circuits.

[0014] In one alternative implementation, the resistance value of the third resistor is less than the resistance value of the seventh resistor, and the resistance value of the seventh resistor is less than the resistance value of the fifth resistor.

[0015] This invention enables voltage division of the pin level by deploying resistors with different resistance values, thereby controlling the level of the low dropout regulator enable pin and realizing the enable control of the low dropout regulator.

[0016] In one alternative implementation, the output current limiting pin of the low dropout regulator is connected to the first pin of the seventh resistor, and the second pin of the seventh resistor is connected to ground, for limiting the output current to a preset maximum output current range based on the seventh resistor.

[0017] This invention allows setting the maximum output current of a low-dropout regulator by setting a resistor on its output current limiting pin, thereby ensuring that the load operates normally within the maximum output current range and preventing false triggering of the short-circuit protection logic.

[0018] Secondly, this utility model provides a power supply circuit for an external active antenna, comprising:

[0019] The vehicle-mounted remote communication terminal is equipped with a positioning module, which is connected to the input pin of the low-dropout regulator in the power supply diagnostic circuit of the first aspect or any of its corresponding embodiments, for providing a power supply for the first voltage.

[0020] An external active antenna is connected to the output pin of the low-dropout regulator and the positioning module. It is used to operate based on the second voltage converted by the low-dropout regulator and to provide a signal to the positioning module.

[0021] The power supply circuit for the external active antenna provided by this utility model can operate based on the stable voltage provided by the low dropout voltage regulator. In turn, the load status can be determined by monitoring the current of the low dropout voltage regulator, avoiding the situation where voltage overlap leads to misjudgment of the working status of the external active antenna, and improving the accuracy of the working status judgment of the external active antenna.

[0022] In one optional implementation, the external active antenna is connected to the positioning module via a filter circuit. The external active antenna is connected to the first pin of the first inductor, and the second pin of the first inductor is connected to the output pin of the low dropout regulator. The external active antenna is also connected to the first pin of the first capacitor, and the second pin of the first capacitor is connected to the filter circuit, which is then connected to the positioning module.

[0023] This invention deploys inductors and capacitors between the external active antenna, the low-dropout regulator, and the positioning module. Based on the "DC-passing, AC-blocking" characteristics of inductors and the "AC-passing, DC-blocking" characteristics of capacitors, it ensures that DC current will not be coupled to the RF pins of the positioning module, and at the same time, RF signals will not be coupled to the power supply pins of the low-dropout regulator.

[0024] In one optional embodiment, the filter circuit includes: a second capacitor, an eighth resistor, and a second inductor, wherein the first pin of the second capacitor and the first pin of the eighth resistor are connected to the second pin of the first capacitor, the second pin of the eighth resistor is connected to the first pin of the second inductor and the positioning module, and the second pin of the second capacitor and the second pin of the second inductor are connected to a ground point.

[0025] This invention, by deploying a filtering circuit, can filter the signal received by an external power supply antenna, remove interference signals, and make the received useful signal clearer.

[0026] In one optional implementation, the rated operating current range of the external active antenna is 10mA-60mA, and the power supply is the primary power supply of the vehicle-mounted remote communication terminal, with a first voltage of 5V and a second voltage of 3.3V.

[0027] This invention amplifies satellite signals by deploying an external active antenna, thereby enabling positioning or timing services. Furthermore, by specifying the operating current and voltage of the external active antenna, it provides a basis for the operating environment of the low-dropout voltage regulator, thus enabling power supply and power supply diagnostics for the external active antenna. Attached Figure Description

[0028] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 The schematic diagram of the power supply circuit for an existing external active antenna;

[0030] Figure 2 This is a schematic diagram of the power supply circuit for the external active antenna according to an embodiment of the present invention.

[0031] Explanation of reference numerals in the attached figures:

[0032] 100 - Low dropout voltage regulator; 200 - First enable module. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0034] This utility model applies to scenarios where power supply is determined based on the load's operating status, using an external active antenna mounted on a vehicle as an example. The vehicle's TBOX (Telematics Box) typically integrates a GNSS (Global Navigation Satellite System) module to provide navigation or timing services, while the external active antenna amplifies the satellite's radio frequency signals. The rated operating voltage of the external active antenna is 3.3V, and the rated operating current range is 10mA-60mA. The TBOX (Telematics Box) is a core component of a vehicle networking system, commonly referred to as an in-vehicle TBOX. Figure 1As shown, the 3.3V power supply comes from inside the TBOX and is controlled by a switching chip to turn off the 3.3V power supply. The corresponding power supply current path is: switching chip → sampling resistor R1 → inductor L1 → external active antenna. Due to the characteristics of inductor L1 "passing DC and blocking AC" and capacitor C1 "passing AC and blocking DC", DC current will not be coupled to the GNSS RF pin, and the RF signal cannot be coupled to the 3.3V power supply.

[0035] like Figure 1 As shown, the diagnosis of the external active antenna's operating status is achieved by acquiring the voltage between resistor R1 and inductor L1 (hereinafter referred to as the diagnostic voltage), and the MCU (Microcontroller Unit) makes a judgment based on the range of the diagnostic voltage. When the antenna is open-circuited, no power supply is needed for the antenna, the current flowing through resistor R1 is almost zero, and the diagnostic voltage is close to the antenna power supply voltage. When the antenna is short-circuited (short-to-ground), the impedance between the 3.3V power supply and ground is extremely small, and a large current will flow through resistor R1, so the diagnostic voltage is close to 0V. When the antenna is working normally, the diagnostic voltage should theoretically be between open-circuit and short-circuit. In actual operation, the actual voltage range of the 3.3V power supply is 3.162V-3.488V, resistor R1 = 10Ω (5% accuracy), and the internal resistance range of the switching chip is 41mΩ-71mΩ. Therefore, the diagnostic voltage range under different conditions can be determined as follows: open circuit: 3.162V-3.488V; normal operation: 2.51V-3.396V; short circuit: 0V-0.5V. Therefore, it is evident that the diagnostic voltage range for an external active antenna in open-circuit mode overlaps with that in normal operation, falling within the range of 3.162V-3.396V, making it impossible to accurately define the antenna's state. Related technologies measure the antenna's three-state voltage under different operating conditions during practical use, providing a range for determining the voltage of different antenna states. However, this calibration method cannot exhaust all possible operating conditions, thus still carries the risk of the TBOX's MCU chip misjudging the antenna state.

[0036] In addition, the MCU determines the antenna status by diagnostic voltage. If a short circuit fault occurs, the MCU uses MCU_IO1 to shut down the switch chip, cutting off power to the antenna and preventing high current from damaging the internal circuitry of the external active antenna or the TBOX board. If the delay between the MCU reading the antenna short circuit status and shutting down the switch chip is too long, or if the MCU is in an abnormal state and cannot shut down the switch chip in time, the circuit may be damaged by high current.

[0037] Therefore, this utility model provides a power supply diagnostic circuit that can avoid overlap of diagnostic voltages under different operating conditions and achieve a fast response. The following is in conjunction with... Figure 2 The following describes embodiments of the present invention.

[0038] According to an embodiment of the present invention, a power supply diagnostic circuit is provided, comprising: a low-dropout regulator 100, with an input pin connected to a power supply and an output pin connected to a load, for converting the power supply from a first voltage to a second voltage to supply power to the load, and for monitoring the output current of the output pin, and determining the level state of the status error pin based on the current monitoring result.

[0039] The first enabling module 200 has a first pin connected to the enable pin of the low-dropout regulator 100 and a second pin connected to the status error reporting pin of the low-dropout regulator 100. It is used to adjust the second level state of the enable pin according to the first level state of the status error reporting pin, so that the low-dropout regulator 100 turns on or off the power supply to the load according to the second level state.

[0040] Specifically, in this embodiment of the invention, the low dropout regulator (LDO) is a linear regulator used to convert the input voltage into a stable output voltage to meet the power requirements of various electronic devices. The core component of the low dropout regulator is the regulating transistor (usually a transistor or field-effect transistor), which operates in the linear region. A feedback circuit monitors the output voltage in real time and compares it with a reference voltage. When the output voltage deviates from the set value, the feedback circuit adjusts the conduction level of the regulating transistor, changing its voltage drop, thereby maintaining a stable output voltage. Compared to traditional linear regulators, the LDO's regulating transistor can operate normally under low dropout conditions; that is, when the difference between the input and output voltages is small, the LDO can still operate normally and maintain a stable output voltage.

[0041] In some optional implementations, LDOs also feature the ability to monitor output current and limit the maximum output current. For the current monitoring function of an LDO, two methods are typically used: ① A small-value sampling resistor is connected in series in the LDO's output circuit. When current flows through this resistor, a voltage drop proportional to the current is generated across it. By accurately measuring and amplifying this voltage drop, an electrical signal related to the output current can be obtained. This signal is then processed by an analog-to-digital converter (ADC) to convert it into a digital signal for analysis and processing by a microcontroller (MCU) or other control unit; ② A dedicated current sensing circuit is integrated internally. This circuit indirectly obtains information about the output current by detecting the conduction state or current change of a regulating transistor (such as a power transistor). This method eliminates the need for an additional sampling resistor, reducing the number of external components and improving circuit integration and reliability. By monitoring the output current in real time, the system can dynamically adjust the LDO's operating state according to the actual load requirements, achieving more efficient power management and helping to quickly locate and diagnose faults in the circuit. For example, abnormal fluctuations or current exceeding the normal range may indicate a short circuit, open circuit, or other fault in the load circuit. Analyzing the current data can accurately determine the location and cause of the fault, facilitating repair and troubleshooting. The maximum limiting current of an LDO refers to the maximum current value that the LDO can stably output without causing damage to itself or the circuit. Different LDO models have different maximum limiting currents, commonly ranging from tens of milliamps to several amps.

[0042] In one optional implementation, the configurable LDO output pin Vout of this embodiment has an output voltage of 3.3V, and the input pin Vin has an input voltage of 5V constant from the primary power supply at the TBOX terminal. This improves efficiency and ensures that the external active antenna can operate normally under a stable 3.3V power supply. Simultaneously, by deploying a resistor R8 between the LDO's output current limiting pin and the ground point, the maximum output current of the LDO can be configured to be slightly higher than 60mA, further ensuring that the external active antenna can operate normally at a current of 60mA without falsely triggering the short-circuit protection logic. However, since the LDO's output voltage is fixed (3.3V), it is impossible to determine the operating state of the external active antenna based on the monitored voltage. Therefore, the operating state of the load is monitored based on the LDO's current monitoring function and maximum output current.

[0043] In some optional embodiments, the LDO detects the current of the output pin Vout. Meanwhile, in order to implement the corresponding functions of the second enabling module 300, the current monitoring logic is preset inside the LDO according to the rated operating current range of the external active antenna, that is, the monitoring voltage in different operating states is determined according to the detected current value, and the monitoring voltage is transmitted to the second enabling module 300 through the output current monitoring pin. The second enabling module 300 of the embodiment of the present invention is the MCU. Figure 2 Only the pin connection situation between the MCU and the LDO is shown in it. The implementation of the internal judgment logic of the MCU is also a conventional technical means in the art and will not be elaborated here. As Figure 2 shown, the MCU-ADC pin of the MCU is connected to the output current monitoring pin of the LDO, and the MCU-IO1 pin is connected to the enabling (EN) pin of the LDO. After the MCU-ADC pin obtains the monitoring voltage of the LDO, the internal logic of the MCU makes a judgment according to the monitoring voltage, and the level of the EN pin is controlled by the MCU_IO1 pin, so as to control the shutdown of the LDO to supply power to the external active antenna. The specific current monitoring logic is as follows: when the antenna is short-circuited, the LDO detects that the output current is greater than 60 mA, and the output current monitoring pin will output a voltage value Vc of V1, V1 is the rated value, and its range is V2 - V3. When the output current is within the range of 0 mA - 60 mA, Vc linearly changes within the range of 0 - V2 according to the output current value, and the monitoring voltage value corresponding to an output current of 10 mA is V4. The setting of the above judgment logic is the basic function of the LDO and belongs to the conventional technical means in the art and will not be elaborated here. Correspondingly, the MCU can judge the working state of the antenna by reading the monitoring voltage through the MCU-ADC pin: when 0 < Vc < V4, it is judged that the antenna is in an open circuit state; when V4 < Vc < V2, it is judged that the antenna is in a normal working state; when V2 < Vc < V3, it is judged that the antenna is in a short-circuit state. It can be seen that there is no intersection between the interval ranges of each monitoring voltage, which can ensure the more accurate judgment result of the working state.

[0044] In some optional embodiments, after the TBOX is powered on and starts up, the MCU controls the enabling of the LDO through the MCU_IO1 pin. During the normal operation of the TBOX, the working state of the LDO can also be judged through the status error reporting pin. This pin is an open-drain output and an external pull-up source needs to be added. When the working state of the LDO is normal, the output of this pin is in a high-impedance state. When the LDO is in an abnormal state, such as an over-current state caused by a short-circuit of the external active antenna, the output of this pin is at a low level. Due to the delay between the MCU reading the antenna short-circuit state and turning off the switch chip, the embodiment of the present invention uses this pin to cooperate with an externally self-built circuit to implement the hardware automatic shutdown of the LDO to supply power to the external active antenna. The self-built circuit is the first enabling module 200 of the embodiment of the present invention.

[0045] In some alternative implementations, such as Figure 2 As shown, the first enable circuit mainly includes two transistors and six resistors, with the following connections: the first pin of transistor Q1 is connected to the status error pin, and the second pin is connected to an external pull-up source; the first pin of resistor R1 is connected to the first pin of transistor Q1, and the second pin is connected to the second pin of transistor Q1; the first pin of resistor R4 is connected to the third pin of transistor Q1, and the second pin is connected to the first pin of transistor Q2; the second pin of transistor Q2 is connected to the first pin of resistor R5, and the third pin is connected to ground; the first pin of resistor R3 is connected to the first pin of transistor Q2, and the second pin is connected to ground; the second pin of resistor R5 and the first pin of resistor R6 are connected to the enable pin EN, and are also connected to the first pin of resistor R7. The second pin of resistor R6 is connected to ground, and the second pin of resistor R7 is connected to the MCU_IO1 pin of the MCU. In this transistor, Q1 is a PNP transistor, Q2 is an NPN transistor, and resistor R6 is chosen with a relatively large value, such as 100kΩ. Resistor R7 is chosen with a relatively small value, such as 10kΩ, and resistor R5 is chosen with an even smaller value, such as 1KΩ. This is just an example and not a limitation. In the PNP transistor, the current mainly flows from the emitter to the collector, and the base current flows from the emitter to the base. For the transistor to function properly, the emitter potential must be higher than the base potential, and the base potential must be higher than the collector potential. Typically, the emitter is connected to the positive power supply, and the collector is connected to the negative power supply. In the NPN transistor, the current flows from the collector to the emitter, and the base current flows from the base to the emitter. The collector potential must be higher than the base potential, and the base potential must be higher than the emitter potential. Generally, the collector is connected to the positive power supply, and the emitter is connected to the negative power supply (usually grounded).

[0046] In some optional implementations, when the external active antenna is detected to be in normal working condition, MCU_IO1 is set high. After voltage division by resistors R6 and R7, the EN pin of the LDO remains high, enabling the LDO and supplying power to the external active antenna. At this time, the status error pin outputs a high-impedance state and is pulled up to a high level, turning off transistors Q1 and Q2. When an antenna short-circuit fault occurs, i.e., the LDO is in an overcurrent state, the status error pin outputs a low level, turning on transistor Q1 and pulling the base of transistor Q2 high. Transistor Q2 then conducts, and after voltage division by resistors R5 and R7, the EN pin is quickly pulled low, turning off the LDO output. Compared to the MCU actively pulling down the LDO's EN pin via MCU_IO1 after detecting a short-circuit fault by judging the Vc voltage, this hardware protection circuit has a faster response speed and can protect the circuit instantly upon the occurrence of a short circuit. However, the hardware protection circuit's pull-down of the EN pin is instantaneous, therefore requiring MCU enable control for coordination. In other words, when the hardware circuit momentarily pulls the EN pin low, the MCU will also disable the LDO in time after detecting the short circuit, thus preventing the LDO's EN pin from being in a state of repeated switching oscillation. At this time, the EN pin can be pulled low before the MCU actively disables the LDO output, thus turning off the LDO output in time. This can both compensate for the delay of the MCU's enable control and avoid the instantaneous control of the hardware circuit, thereby protecting the circuit from damage caused by short circuit faults.

[0047] The power supply diagnostic circuit provided in this embodiment of the invention converts the power supply voltage using a low-dropout regulator and determines the level state of the error reporting pin by monitoring the output current of the output pin. The enable module adjusts the level state of the enable pin according to the level state of the error reporting pin of the low-dropout regulator, so that the low-dropout regulator turns on or off the power supply to the load according to the level state of the enable pin. This invention, through the working characteristics of the low-dropout regulator itself and the cooperation of an external self-built circuit, can provide a relatively stable voltage to the load. It achieves load status judgment through current monitoring, avoiding voltage overlap and improving the accuracy of load status judgment. Furthermore, it can quickly respond to abnormal states, realizing the circuit function of shutting off immediately upon overcurrent, providing timely instantaneous protection for the load circuit and preventing damage due to excessive current during load short circuits.

[0048] According to an embodiment of the present invention, another aspect provides a power supply circuit for an external active antenna, comprising: a vehicle-mounted remote communication terminal, equipped with a positioning module, and the same as described above. Figure 2 The input pin of the low-dropout regulator is connected to provide the power supply for the first voltage; the external active antenna is connected to the output pin of the low-dropout regulator and the positioning module, and is used to operate based on the second voltage converted by the low-dropout regulator to provide a signal to the positioning module.

[0049] Specifically, in the embodiments of this utility model, such as Figure 2 As shown, TBOX is a vehicle-mounted remote communication terminal with a built-in GNSS module. An external active antenna is connected to the first pin of inductor L1, and the second pin of inductor L1 is connected to the output pin of the low-dropout regulator. Simultaneously, the external active antenna is connected to the first pin of capacitor C1, the second pin of capacitor C1 is connected to the filter circuit, and the filter circuit is connected to the positioning module. Based on the characteristics of inductor L1 ("passing DC, blocking AC") and capacitor C1 ("passing AC, blocking DC"), the DC power provided by the LDO will not couple to the GNSS module's RF port, and the RF signal cannot be coupled to the 3.3V power supply. The filter circuit includes capacitor C2, resistor R2, and inductor L2. The first pins of capacitor C2 and resistor R2 are connected to the second pin of capacitor C1. The second pin of resistor R2 is connected to the first pin of inductor L2 and the GNSS module. The second pins of capacitor C2 and inductor L2 are connected to the ground point. Filtering circuits can implement π-filtering in the radio frequency (RF) path to filter RF signals. Capacitors, with their DC-blocking and AC-passing characteristics, exhibit different impedances for different frequencies. In RF circuits, capacitors have very low impedance to high-frequency signals, essentially acting as a short circuit, thus bypassing high-frequency interference signals to ground. When an RF signal passes through a π-type filter, the capacitor guides high-frequency noise components to ground, reducing the impact of high-frequency interference on the signal. Inductors impede changes in current, and their impedance increases with signal frequency. In a π-type filter, the inductor connected in series in the signal path significantly impedes high-frequency signals, making it difficult for them to pass, while offering less impediment to low-frequency signals or signals of specific frequencies, thus achieving signal frequency filtering.

[0050] The power supply circuit for the external active antenna provided in this embodiment of the utility model can operate based on the stable voltage provided by the low dropout voltage regulator. In turn, the load status can be determined by monitoring the current of the low dropout voltage regulator, avoiding the situation where voltage overlap leads to misjudgment of the working status of the external active antenna, and improving the accuracy of the working status judgment of the external active antenna.

[0051] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and all such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A power supply diagnostic circuit, characterized in that, include: The low dropout regulator (100) has an input pin connected to the power supply and an output pin connected to the load. It is used to convert the power supply from a first voltage to a second voltage to supply power to the load, and to monitor the output current of the output pin. Based on the current monitoring result, it determines the level state of the status error pin. A first enabling module (200) has a first pin connected to the enabling pin of the low-dropout regulator (100) and a second pin connected to the status error reporting pin of the low-dropout regulator (100). The module is used to adjust the second level state of the enabling pin according to the first level state of the status error reporting pin, so that the low-dropout regulator (100) turns on or off the power supply to the load according to the second level state.

2. The power supply diagnostic circuit according to claim 1, characterized in that, Also includes: The second enable module (300) has a first pin connected to the output current monitoring pin of the low dropout regulator and a second pin connected to the first pin of the enable module. It is used to determine the third level state input to the enable pin based on the monitoring voltage output by the output current monitoring pin after the low dropout regulator determines the monitoring voltage based on the current monitoring result.

3. The power supply diagnostic circuit according to claim 2, characterized in that, The first enabling module includes: The first transistor has its first pin connected to the status error pin and its second pin connected to an external pull-up source. The first resistor has its first pin connected to the first pin of the first transistor, and its second pin connected to the second pin of the first transistor. The second resistor has its first pin connected to the third pin of the first transistor, and its second pin connected to the first pin of the second transistor. The second pin of the second transistor is connected to the first pin of the third resistor, and the third pin is connected to the ground point; The fourth resistor has its first pin connected to the first pin of the second transistor and its second pin connected to the ground point. The second pin of the third resistor and the first pin of the fifth resistor are connected to the enable pin and the first pin of the seventh resistor. The second pin of the fifth resistor is connected to the ground point, and the second end of the sixth resistor is connected to the second pin of the second enable module.

4. The power supply diagnostic circuit according to claim 3, characterized in that, The first transistor is a PNP transistor, and the second transistor is an NPN transistor.

5. The power supply diagnostic circuit according to claim 3, characterized in that, The resistance value of the third resistor is less than the resistance value of the seventh resistor, and the resistance value of the seventh resistor is less than the resistance value of the fifth resistor.

6. The power supply diagnostic circuit according to claim 2, characterized in that, The output current limiting pin of the low dropout regulator is connected to the first pin of the seventh resistor, and the second pin of the seventh resistor is connected to the ground point, which is used to limit the output current within a preset maximum output current range based on the seventh resistor.

7. A power supply circuit for an external active antenna, characterized in that, include: The vehicle-mounted remote communication terminal is equipped with a positioning module, which is connected to the input pin of the low-dropout regulator in the power supply diagnostic circuit according to any one of claims 1 to 6, for providing a power supply for a first voltage. An external active antenna is connected to the output pin of the low-dropout regulator and the positioning module, and is used to operate based on the second voltage converted by the low-dropout regulator to provide a signal to the positioning module.

8. The power supply circuit according to claim 7, characterized in that, The external active antenna is connected to the positioning module via a filtering circuit, wherein, The external active antenna is connected to the first pin of the first inductor, and the second pin of the first inductor is connected to the output pin of the low dropout regulator. The external active antenna is connected to the first pin of the first capacitor, the second pin of the first capacitor is connected to the filter circuit, and the filter circuit is connected to the positioning module.

9. The power supply circuit according to claim 8, characterized in that, The filtering circuit includes a second capacitor, an eighth resistor, and a second inductor. The first pin of the second capacitor and the first pin of the eighth resistor are connected to the second pin of the first capacitor. The second pin of the eighth resistor is connected to the first pin of the second inductor and the positioning module. The second pin of the second capacitor and the second pin of the second inductor are connected to a ground point.

10. The power supply circuit according to claim 7, characterized in that, The rated operating current range of the external active antenna is 10mA-60mA, and the power supply is the primary power supply of the vehicle-mounted remote communication terminal, with the first voltage being 5V and the second voltage being 3.3V.

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