A dual-loop standby control circuit and a switching power supply

Abstract

The present invention provides a dual-loop standby control circuit and a switching power supply, relating to the electronic field. The control circuit includes: a first voltage dividing module, a second voltage dividing module, a first control module, and a second control module; the input end of the first voltage dividing module is connected to the power supply port, converts the power supply voltage into an initial reference voltage and divides the initial reference voltage; the second voltage dividing module is connected to the power supply port and divides the power supply voltage to obtain a power supply divided voltage; the input end of the first control module is respectively connected to the output end of the first voltage dividing module, the output end of the second voltage dividing module, and the set enable port; the output end of the first control module is connected to the power supply end enable port; the first control module outputs a power supply port enable signal; the second control module is respectively connected to the feedback port, the first voltage dividing module, the feedback end enable port, and the set enable port, and outputs a feedback port enable signal. The present invention can meet the requirements of the standby hold skip cycle mode.

Description

Technical Field

[0001] The present invention relates to the field of electronics, and particularly to a dual-loop standby control circuit and a switching power supply. Background Art

[0002] As a power supply device for portable electronic products, the power supply has been developing towards miniaturization, safety, and high efficiency. Therefore, products in the small package SOT23-6L are popular in the market. However, with the improvement of energy efficiency standards, in order to pursue the reduction of standby power consumption, each company has adopted the working mode of standby skip cycle mode in the ultra-small package SOT23-6L products to meet the standby power consumption energy efficiency standards. Due to the limitation of the control chip pin safety regulations in the ultra-small package SOT23-6L products, high-voltage startup cannot be adopted, and only the external resistor startup method can be used to complete the power-on startup of the system. In the case of resistor startup, the power supply pin VDD is likely to lose power during standby, resulting in an automatic restart malfunction. Therefore, in order to prevent VDD from losing power, some advanced manufacturers usually adopt the control of exiting the skip cycle mode before VDD drops to the power-down threshold VDD OFF to avoid power loss. Summary of the Invention

[0003] The purpose of the present invention is to provide a dual-loop standby control circuit and a switching power supply to meet the requirement of maintaining the skip cycle mode during standby.

[0004] To achieve the above purpose, the present invention provides the following solutions:

[0005] A dual-loop standby control circuit, the control circuit includes: a first voltage dividing module, a second voltage dividing module, a first control module, and a second control module;

[0006] The input end of the first voltage dividing module is connected to the power supply port; the first voltage dividing module is used to convert the power supply voltage provided by the power supply port into an initial reference voltage and output it, and divide the initial reference voltage to output a first reference voltage, a second reference voltage, a third reference voltage, a fourth reference voltage, and a fifth reference voltage;

[0007] The second voltage dividing module is connected to the power supply port; the second voltage dividing module is used to divide the power supply voltage to obtain a power supply divided voltage;

[0008] The first control module includes: a first comparator, a first inverter, a first switch, and a second switch;

[0009] The first terminal of the first comparator is connected to the output terminal of the second voltage dividing module; the second terminal of the first comparator is respectively connected to the drain of the first switch and the drain of the second switch; the third terminal of the first comparator is connected to the input terminal of the first inverter; the third terminal of the first comparator is also connected to the power supply terminal enable port to output a power supply terminal enable signal;

[0010] The source of the first switch is connected to the output terminal of the third reference voltage; the source of the second switch is connected to the output terminal of the second reference voltage;

[0011] The fourth terminal of the first comparator is connected to the output terminal of the first reference voltage; the fifth terminal of the first comparator is connected to the set enable port;

[0012] The output terminal of the first inverter is connected to the gate of the second switch; the source of the second switch is connected to the output terminal of the second reference voltage; the gate of the first switch is connected to the power supply terminal enable port;

[0013] The source of the first switch is connected to the output terminal of the third reference voltage;

[0014] The second control module includes: a second comparator, a second inverter, a third switch, and a fourth switch;

[0015] The first terminal of the second comparator is connected to the feedback port;

[0016] The second terminal of the second comparator is respectively connected to the drain of the third switch and the drain of the fourth switch; the third terminal of the second comparator is connected to the input terminal of the second inverter; the third terminal of the second comparator is also connected to the feedback terminal enable port to output a feedback terminal enable signal;

[0017] The fifth terminal of the second comparator is connected to the set enable port; the fourth terminal of the second comparator is connected to the output terminal of the first reference voltage;

[0018] The source of the fourth switch is connected to the output terminal of the fourth reference voltage; the source of the third switch is connected to the output terminal of the fifth reference voltage; the gate of the third switch is connected to the feedback terminal enable port;

[0019] The output terminal of the second inverter is connected to the gate of the fourth switch.

[0020] Optionally, the first voltage dividing module includes: a voltage transformer, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, and a seventh resistor connected in sequence;

[0021] The voltage transformer is connected to the power supply port; the voltage transformer is configured to convert the power supply voltage into an initial reference voltage and divide the initial reference voltage to obtain the first reference voltage;

[0022] The third resistor is connected to the voltage transformer, and the third resistor is configured to divide the first reference voltage to obtain the second reference voltage;

[0023] The fourth resistor is connected to the third resistor, and the fourth resistor is configured to divide the second reference voltage to obtain the third reference voltage;

[0024] The fifth resistor is connected to the fourth resistor, and the fifth resistor is configured to divide the third reference voltage to obtain the fourth reference voltage;

[0025] The sixth resistor is connected to the fifth resistor, and the sixth resistor is configured to divide the fourth reference voltage to obtain the fifth reference voltage;

[0026] One end of the seventh resistor is connected to the sixth resistor and the other end is grounded.

[0027] Optionally, the second voltage division module includes: a first resistor and a second resistor;

[0028] One end of the first resistor is connected to the power supply port, and the other end of the first resistor is connected to one end of the second resistor; the other end of the second resistor is grounded; the connection end between the first resistor and the second resistor is the output end of the second voltage division module.

[0029] A dual-loop standby switching power supply, the switching power supply includes: a voltage input module, a feedback circuit module, and a controller integrated circuit module; the controller integrated circuit module includes a power-on / off enable circuit, a drive circuit, a pulse modulator, and the above-mentioned dual-loop standby control circuit;

[0030] The input end of the voltage input module is connected to the input line voltage end, and the output end of the voltage input module is respectively connected to the power supply port and the input end of the feedback circuit module; the output end of the feedback circuit module is respectively connected to the feedback port and the current monitoring port;

[0031] The input end of the pulse modulator is respectively connected to the feedback port, the current monitoring port, and the power supply port; the output end of the pulse modulator is connected to the drive circuit;

[0032] The input end of the power-on / off enable circuit is connected to the power supply port; the output end of the power-on / off enable circuit is connected to the set enable port;

[0033] The input terminals of the driving circuit are respectively connected to the power supply port, the feedback terminal enabling port, and the power supply enabling port; the output terminal of the driving circuit is connected to the driving output port.

[0034] Optionally, the feedback circuit module includes: a voltage conversion sub-module and a feedback device;

[0035] The input terminal of the voltage conversion sub-module is connected to the output terminal of the voltage input module; the output terminal of the voltage conversion sub-module is connected to the feedback device;

[0036] The output terminal of the feedback device is connected to the feedback port;

[0037] Optionally, the feedback circuit module further includes: a power switch;

[0038] The drain of the power switch is connected to the output terminal of the voltage input module through the primary coil; the source of the power switch is connected to the current monitoring port; the gate of the power switch is connected to the driving output port.

[0039] Optionally, the feedback circuit module further includes: a current limiting resistor;

[0040] One end of the current limiting resistor is connected to the source of the power switch and the other end is grounded.

[0041] Optionally, the voltage conversion sub-module includes: a transformer, a diode, and a capacitor;

[0042] The transformer includes a primary coil and a secondary coil; the primary coil is respectively connected to the output terminal of the voltage input module and the drain of the power switch; the secondary coil is respectively connected to the anode of the diode and the capacitor; the cathode of the diode is connected to the capacitor.

[0043] According to the specific embodiments provided by the present invention, the following technical effects are disclosed by the present invention:

[0044] After the power supply voltage is divided by the first voltage dividing module and the second voltage dividing module, the first control module and the second control module are respectively connected to the first voltage dividing module and the second voltage dividing module to output a power supply port enable signal and a feedback port enable signal. Since the first inverter in the first control module inverses the power supply port enable signal to control the on-off state of the second switch, and since the output signals of the drain of the first switch and the drain of the second switch act on the first comparator, the second terminal of the first comparator can select the second reference voltage and the third reference voltage; similarly, the second inverter in the second control module inverses the feedback port enable signal to control the on-off state of the fourth switch. Since the output signals of the drain of the third switch and the drain of the fourth switch act on the second comparator, the second terminal of the second comparator can select the fourth reference voltage and the fifth reference voltage; therefore, by selectively controlling the input voltages of the first control module and the second control module, the stability of the output voltage and the implementation of the skip cycle operation can be completed, so as to meet the requirements of the standby hold skip cycle mode. Description of the Drawings

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0046] Figure 1 The circuit diagram of the dual-loop standby control circuit provided by the embodiment of the present invention;

[0047] Figure 2 The circuit diagram of the dual-loop standby switching power supply provided by the embodiment of the present invention;

[0048] Figure 3 The waveform diagram of the heavy load to no-load standby switching of the dual-loop standby switching power supply provided by the embodiment of the present invention;

[0049] Figure 4 The circuit diagram of the traditional switching power supply;

[0050] Figure 5 The waveform diagram of the heavy load to no-load standby switching of the traditional switching power supply system;

[0051] Figure 6 The working waveform diagram of the traditional switching power supply system.

[0052] Symbol Description:

[0053] The first voltage dividing module - 1, the second voltage dividing module - 2, the first control module - 3, the second control module - 4, the voltage input module - 5, the feedback circuit module - 6, and the voltage conversion sub - module - 7. Detailed implementation manners

[0054] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0055] The purpose of the present invention is to provide a dual - loop standby control circuit and a switching power supply. After the power supply voltage is divided by the first voltage dividing module and the second voltage dividing module, the first control module and the second control module are respectively connected to the first voltage dividing module and the second voltage dividing module to output a power supply port enable signal and a feedback port enable signal. Since the first inverter in the first control module takes the inverse of the power supply port enable signal to control the on - off state of the second switch, and since the output signals of the drain of the first switch and the drain of the second switch act on the first comparator, the second terminal of the first comparator can select between the second reference voltage and the third reference voltage; similarly, the second inverter in the second control module takes the inverse of the feedback port enable signal to control the on - off state of the fourth switch. Since the output signals of the drain of the third switch and the drain of the fourth switch act on the second comparator, the second terminal of the second comparator can select between the fourth reference voltage and the fifth reference voltage; therefore, by selectively controlling the input voltages of the first control module and the second control module, the stability of the output voltage and the implementation of the skip - cycle operation can be completed to meet the requirements of the standby - hold skip - cycle mode.

[0056] To make the above - mentioned objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners.

[0057] First, the main component symbols appearing in the embodiments of the present invention are described:

[0058] 10: Conventional switching power supply.

[0059] 10A: The dual - loop standby switching power supply provided by the present invention.

[0060] 11: Conventional switching power supply controller integrated circuit module.

[0061] 11A: The switching power supply controller integrated circuit module of the present invention.

[0062] 12: Feedback; 20: Undervoltage Lockout (UVLO); 30: Pulse Width Modulator (PWM); 40: Driver; 50: Standby Control Circuit (STB) inside 11.

[0063] 50A: A Dual-Loop Standby Control Circuit (DLSTB) inside 11A.

[0064] 60A: Timing waveform diagram of two instances of the heavy load to light load switching of the switching power supply 10.

[0065] 60B: Timing waveform diagram of the heavy load to light load switching of the switching power supply 10A.

[0066] STB Mode1: Waveform of the heavy load to light load switching in the case where the switching power supply 10 does not have protection against VDD port power loss.

[0067] STB Mode2: Waveform of the heavy load to light load switching in the case where the switching power supply 10 has protection against VDD port power loss.

[0068] DLSTB Mode: Timing waveform of the heavy load to light load switching of the switching power supply 10A.

[0069] 70: Operating waveform of the switching power supply 10.

[0070] M1: Power switch transistor, with its first terminal as the drain, the second terminal as the gate, and the third terminal as the source.

[0071] TR: Transformer; Lp: Primary coil of TR; Ls: Secondary coil of TR.

[0072] La: Auxiliary coil of TR, responsible for supplying power to the capacitor C at the VDD port VDD Power supply.

[0073] D1: Full-wave rectifier diode for AC input.

[0074] D2, D3: Diodes, with their first terminal as the cathode and the second terminal as the anode.

[0075] Rst: Startup resistor of the switching power supply 10.

[0076] R1, Rx, Rcs, R51, R52, R53, R54, R55, R56, R57: Resistors; where R51 is the first resistor, R52 is the second resistor, R53 is the third resistor, R54 is the fourth resistor, R55 is the fifth resistor, R56 is the sixth resistor, and R57 is the seventh resistor.

[0077] C1, Cx, C VDD and C2: Capacitors.

[0078] M50, M51, M52, M53: N-type switches, where the first terminal is the drain, the second terminal is the gate, and the third terminal is the source; among them, M50 is the first switch, M51 is the second switch, M52 is the third switch, and M53 is the fourth switch.

[0079] 51: The first comparator, where the first terminal is the positive input terminal, the second terminal is the negative input terminal, and the third terminal is the output terminal. The output terminal is in the same phase as the positive terminal, that is, when the voltage of the positive terminal is higher than that of the negative terminal, the output is logic high, otherwise the output is logic low.

[0080] 53: The second comparator, where the first terminal is the positive input terminal, the second terminal is the negative input terminal, and the third terminal is the output terminal. The output terminal is in the same phase as the positive terminal, that is, when the voltage of the positive terminal is higher than that of the negative terminal, the output is logic high, otherwise the output is logic low.

[0081] 52: The first inverter, whose output signal is the inversion of the input signal, that is, when the input is logic high, the output is logic low.

[0082] 54: The second inverter, whose output signal is the inversion of the input signal, that is, when the input is logic high, the output is logic low.

[0083] 55: A voltage regulator (VREF), whose input is a voltage signal and the output is a reference voltage vref.

[0084] VDD: Power supply port; FB: Feedback port; CS: Current monitoring port; DRV: Drive output port; GND: Ground port; VAC: Input line voltage.

[0085] Vo: DC output voltage of the switching power supply 10; Ics: Primary coil current of the transformer TR.

[0086] Vsw: Switching signal; V FB : Feedback voltage; V DD : Voltage of the power supply port, that is, the power supply voltage.

[0087] V PWM : Output signal of the pulse width comparator; EN: Enable signal output by the UVLO functional block.

[0088] vref: Voltage of the second terminal of the voltage regulator 55, that is, the first reference voltage.

[0089] vref1: Second reference voltage; vref2: Third reference voltage; vref3: Fourth reference voltage; vref4: Fifth reference voltage.

[0090] V DD1 : V DD 's voltage division, that is, the power supply voltage division.

[0091] VSTB_VDD : V DD The standby control output logic enable signal of DD , i.e., the power supply port enable signal.

[0092] V STB_VDD_N : V STB_VDD The reverse signal of STB_VDD .

[0093] V STB_FB : V FB The standby control output logic enable signal of FB , i.e., the feedback port enable signal.

[0094] V STB_FB_N : V STB_FB The reverse of STB_FB ; △Vo: The maximum ripple value of the output voltage Vo; I O : The secondary side output current; VDD hold2 : The VDD voltage hold-off threshold; VDD hold1 : The VDD voltage hold threshold.

[0095] VDD OFF : The VDD voltage power-down threshold; VDD ON : The VDD voltage power-up threshold.

[0096] V FB_OUT : The skip cycle mode exit voltage threshold; V FB_IN : The skip cycle mode entry voltage threshold.

[0097] V FB_REF : The input voltage of the second terminal of the second comparator 53.

[0098] V VDD_REF : The input voltage of the second terminal of the first comparator 51.

[0099] Skip cycle mode: i.e., no-load standby mode.

[0100] "1": Logic high.

[0101] "0": Logic low.

[0102] Embodiment 1

[0103] As Figure 1 shown, the dual-loop standby control circuit provided in this embodiment includes: a first voltage dividing module 1, a second voltage dividing module 2, a first control module 3, and a second control module 4.

[0104] The input end of the first voltage dividing module 1 is connected to the power supply port VDD; the first voltage dividing module 1 is used to divide the power supply voltage V provided by the power supply port VDD DDConvert it into an initial reference voltage and output it, and divide the initial reference voltage to output the first reference voltage vref, the second reference voltage vref1, the third reference voltage vref2, the fourth reference voltage vref3, and the fifth reference voltage vref4.

[0105] Specifically, the first voltage division module 1 includes: a voltage transformer 55 (VREF), a third resistor R53, a fourth resistor R54, a fifth resistor R55, a sixth resistor R56, and a seventh resistor R57; the voltage transformer 55 (VREF) is connected to the power supply port VDD; the voltage transformer 55 (VREF) is used to convert the power supply voltage V DD into a reference voltage and divide the reference voltage to obtain the first reference voltage vref; the third resistor R53 is connected to the voltage transformer 55 (VREF), and the third resistor R53 is used to divide the first reference voltage vref to obtain the second reference voltage vref1; the fourth resistor R54 is connected to the third resistor R53, and the fourth resistor R54 is used to divide the second reference voltage vref1 to obtain the third reference voltage vref2; the fifth resistor R55 is connected to the fourth resistor R54, and the fifth resistor R55 is used to divide the third reference voltage vref2 to obtain the fourth reference voltage vref3; the sixth resistor R56 is connected to the fifth resistor R55, and the sixth resistor R56 is used to divide the fourth reference voltage vref3 to obtain the fifth reference voltage vref4; the seventh resistor R57 is connected to the sixth resistor R56 and the other end thereof is grounded.

[0106] The second voltage division module 2 is connected to the power supply port VDD; the second voltage division module 2 is used to divide the power supply voltage V DD to obtain a power supply divided voltage V DD1 .

[0107] Specifically, the second voltage division module 2 includes a first resistor R51 and a second resistor R52; one end of the first resistor R51 is connected to the power supply port VDD, and the other end of the first resistor R51 is connected to one end of the second resistor R52; the other end of the second resistor R52 is grounded; the connection end between the first resistor R51 and the second resistor R52 is the output end of the second voltage division module 2.

[0108] The input ends of the first control module 3 are respectively connected to the output end of the first voltage division module 1, the output end of the second voltage division module 2, and the set enable port; the output end of the first control module 3 is connected to the power supply end enable port; the first control module 3 is used to output a power supply port enable signal V DD1 under the action of the power supply divided voltage V STB_VDD .

[0109] Specifically, the first control module 3 includes: a first comparator 51, a first inverter 52, a first switch M50, and a second switch M51.

[0110] The first terminal of the first comparator 51 is connected to the output terminal of the second voltage dividing module 2; the second terminal of the first comparator 51 is respectively connected to the drain of the first switch M50 and the drain of the second switch M51; the third terminal of the first comparator 51 is connected to the input terminal of the first inverter 52; the third terminal of the first comparator 51 is also connected to the power supply terminal enable port to output a power supply terminal enable signal V STB_VDD ; the fourth terminal of the first comparator 51, the source of the first switch M50, and the source of the second switch M51 are all connected to the output terminal of the first voltage dividing module 1; the fourth terminal of the first comparator 51 is connected to the output terminal of the first reference voltage vref; the fifth terminal of the first comparator 51 is connected to the set enable port; the output terminal of the first inverter 52 is connected to the gate of the second switch M51; the source of the second switch M51 is connected to the output terminal of the second reference voltage vref1; the gate of the first switch M50 is connected to the power supply terminal enable port; the source of the first switch M50 is connected to the output terminal of the third reference voltage vref2.

[0111] The second control module 4 is respectively connected to the feedback port, the first voltage dividing module 1, the feedback terminal enable port, and the set enable port. The second control module 4 is configured to output a feedback port enable signal under the action of the first reference voltage vref, the fourth reference voltage vref3, the fifth reference voltage vref4, and the set enable port.

[0112] Specifically, the second control module 4 includes: a second comparator 53, a second inverter 54, a third switch M52, and a fourth switch M53; the first terminal of the second comparator 53 is connected to the feedback port FB; the second terminal of the second comparator 53 is respectively connected to the drain of the third switch M52 and the drain of the fourth switch M53; the third terminal of the second comparator 53 is connected to the input terminal of the second inverter 54; the third terminal of the second comparator 53 is also connected to the feedback terminal enable port to output a feedback port enable signal V STB_FB ; the fifth terminal of the second comparator 53 is connected to the set enable port; the fourth terminal of the second comparator 53 is connected to the port of the first voltage dividing module 1 that outputs the first reference voltage vref.

[0113] The source of the fourth switch M53 is connected to the port of the first voltage dividing module 1 that outputs the fourth reference voltage vref3; the source of the third switch M52 is connected to the port of the first voltage dividing module 1 that outputs the fifth reference voltage vref4; the gate of the third switch M52 is connected to the feedback terminal enable port; the output terminal of the second inverter 54 is connected to the gate of the fourth switch M53.

[0114] The dual-loop standby control circuit provided in this example consists of resistors R51, R52, R53, R54, R55, R56, R57, where R51 is the first resistor, R52 is the second resistor, R53 is the third resistor, R54 is the fourth resistor, R55 is the fifth resistor, R56 is the sixth resistor, and R57 is the seventh resistor; a voltage transformer 55, a first comparator 51, a second comparator 53, a first inverter 52, a second inverter 54, switches M50, M51, switch M52, and switch M53 are connected according to electrical properties; where M50 is the first switch, M51 is the second switch, M52 is the third switch, and M53 is the fourth switch; this control circuit can perform dual-loop standby control on the VDD port, that is, the power supply port, and the V FB port, that is, the feedback port, so that it not only meets the standby energy efficiency but also avoids the oscillation problem when switching from heavy load to no-load standby, which not only ensures the safety of the user's electrical equipment but also improves the efficiency of the user's electrical equipment, and has a high market application prospect.

[0115] The working principle of the dual-loop standby control circuit 50A provided in this embodiment is as follows:

[0116] During the process of VDD powering on from 0, when V DD <VDD ON (VDD ON is the power-on threshold), EN is logic "0", and the outputs of all comparators are set to logic "1". When V DD >VDD ON the circuit enters the normal working mode. The voltage V DD of the VDD port is input to the voltage transformer 55 and then outputs the first reference voltage vref. In addition, V DD is divided by the first resistor R51 and the second resistor R52 to obtain the voltage detection signal V DD1 , and V DD1 is input to the first terminal of the first comparator 51. The first reference voltage vref is divided by the series resistors, that is, the fourth resistor R54, the fifth resistor R55, the sixth resistor R56, and the seventh resistor R57, to generate the second reference voltage vref1, the third reference voltage vref2, the fourth reference voltage vref3, and the fifth reference voltage vref4 respectively. The first switch M50 and the second switch M51 are the selection switches for the second reference voltage vref1 and the third reference voltage vref2 of the input signal V VDD_REF at the second terminal of the first comparator 51, while the third switch M52 and the fourth switch M53 are the input signal V FB_REFA selection switch for the fourth reference voltage Vref3 and the fifth reference voltage Vref4. After the first inverter 52 inverts the output logic of the first comparator 51, it controls the on and off of the second switch M51. After the second inverter 54 inverts the output logic of the second comparator 53, it controls the on and off of the fourth switch M53.

[0117] The first resistor R51 and the second resistor R52 are ultra-large resistors with a matching ratio coefficient of β (0 < β < 1), and the third resistor R53, the fourth resistor R54, the fifth resistor R55, the sixth resistor R56, and the seventh resistor R57 are precision resistors with matching ratio coefficients of θ1, θ2, θ3, θ4 (0 < θ4 < θ3 < θ2 < θ1 < 1).

[0118] R52 = β(R51 + R52).

[0119] R57 = θ4(R53 + R54 + R55 + R56 + R57).

[0120] R56 + R57 = θ3(R53 + R54 + R55 + R56 + R57).

[0121] R55 + R56 + R57 = θ2(R53 + R54 + R55 + R56 + R57).

[0122] R54 + R55 + R56 + R57 = θ1(R53 + R54 + R55 + R56 + R57).

[0123] Vref1 = θ1 × vref.

[0124] Vref2 = θ2 × vref.

[0125] Vref3 = θ3 × vref.

[0126] Vref4 = θ4 × vref.

[0127] V DD1 = β × VDD.

[0128] Although there are many implementation solutions to solve the power-off phenomenon in the prior art, and it can also help customers design a switching power supply system more easily, when switching from heavy load to no load in the prior art, the switching power supply system will work in a non-skipping cycle mode, greatly increasing the switching loss and unable to meet the standby power consumption energy efficiency standard. Therefore, it is necessary to adopt special technologies to avoid the above problems and meet the energy efficiency standard, so as to protect the safety and efficiency of electrical equipment.

[0129] The circuit diagram of a traditional switching power supply is as Figure 4 shown, and the working waveform of the traditional switching power supply is as Figure 6As shown in the figure. After the output voltage Vo of the secondary side of the transformer TR is sampled by the feedback device 12, it is transmitted to the FB port of the power converter 11. The current Ics in the primary side coil of the transformer is sampled through the power switch tube M1 and the current-limiting resistor Rcs to the power converter 11, that is, the current Ics reaches the CS port of the traditional switching power supply controller integrated circuit module to generate a square wave signal (Vsw) with a variable pulse width to control the on and off of the power switch tube (M1), thereby completing the energy transmission of the transformer TR. Since the traditional switching power supply 10 starts with a resistor, in order to meet the energy efficiency standard of standby power consumption, its standby operating mode adopts the skip cycle mode. One of its disadvantages is that when switching from heavy load to no-load standby, the VDD port is prone to power-off, resulting in oscillation of the output voltage Vo of the switching power supply system; the second disadvantage is that if anti-power-off technology is added to it, when switching from heavy load to no-load standby, it will work in a non-skip cycle mode, bringing great switching losses and causing the problem of exceeding the standby power consumption standard. As Figure 5 shown, where STB Mode1 is the situation of the first disadvantage and STB Mode2 is the situation of the second disadvantage. Therefore, it is necessary to adopt special technologies to avoid the above problems and meet the energy efficiency standard, so as to protect the safety and efficiency of electrical equipment.

[0130] Therefore, the present invention also provides a switching power supply based on the control circuit in Embodiment 1 of the present invention to achieve the safety and efficiency of electrical equipment. For details, see Embodiment 2.

[0131] Embodiment 2

[0132] As Figure 2 shown, the dual-loop standby switching power supply provided by the embodiment of the present invention includes: a voltage input module 5, a feedback circuit module 6, and a controller integrated circuit module 11A; the controller integrated circuit module 11A includes a power-on and power-off enabling circuit 20, a driving circuit 40, a pulse modulator 30, and the dual-loop standby control circuit in Embodiment 1.

[0133] The input end of the voltage input module 5 is connected to the input line voltage end (i.e., the port of VAC), and the output end of the voltage input module is respectively connected to the power supply port VDD and the input end of the feedback circuit module 6; the output end of the feedback circuit module 6 is respectively connected to the feedback port FB and the current monitoring port CS.

[0134] The feedback circuit module 6 is used to obtain a DC output voltage under the action of the voltage input module 5; the feedback circuit module 6 feeds back the DC output voltage to the feedback port FB, and at this time, the voltage fed back to the feedback port FB is used as the feedback voltage; the feedback circuit module 6 is also used to output the primary coil current.

[0135] The input terminals of the pulse modulator 30 are respectively connected to the feedback port FB, the current monitoring port CS, and the power supply port VDD; the output terminal of the pulse modulator 30 is connected to the drive circuit 40.

[0136] The pulse modulator 30 is used to output a switching signal Vsw under the action of the feedback circuit module 6, namely the primary coil current, the feedback voltage, and the power supply voltage V DD .

[0137] The input terminal of the power-on and power-off enabling circuit 20 is connected to the power supply port VDD; the output terminal of the power-on and power-off enabling circuit 20 is connected to the set enabling port EN; the power-on and power-off enabling circuit 20 is used to receive the power supply voltage V DD and output an enabling signal EN; the output terminal of the power-on and power-off enabling circuit 20 is connected to the set enabling port; the enabling signal EN is used to perform an initial set on the control circuit.

[0138] The input terminals of the drive circuit 40 are respectively connected to the power supply port VDD, the feedback terminal enabling port, and the power supply terminal enabling port; the output terminal of the drive circuit 40 is connected to the drive output port DRV. The drive circuit 40 is used to output a load drive signal under the action of the power supply voltage V DD , the power supply port enabling signal V STB_VDD and the feedback port enabling signal V STB_FB , and output it from the drive output port DRV. The drive circuit 40 is also used to adjust the pulse width of the feedback circuit module 6 according to the switching signal Vsw. In one embodiment, the feedback circuit module 6 specifically includes a voltage conversion sub-module 7 and a feedback device 12; the input terminal of the voltage conversion sub-module 7 is connected to the output terminal of the voltage input module 5; the output terminal of the voltage conversion sub-module 7 is connected to the feedback device 12.

[0139] Specifically, the voltage conversion sub-module 7 includes: a transformer TR, a diode D3, and a capacitor C2; the transformer TR includes a primary coil LP and a secondary coil LS; the primary coil LP is connected to the output terminal of the voltage input module 5 and to the drain of the power switch M1; the secondary coil LS is connected to the anode of the diode D3 and to the capacitor C2; the cathode of the diode D3 is also connected to the capacitor C2. The voltage conversion sub-module 7 is used to convert the voltage output from the output terminal of the voltage input module 5 to obtain an output voltage V0; the output terminal of the feedback device 12 is connected to the feedback port FB; the feedback device 12 is used to selectively sample the output voltage V0 and transmit it to the feedback port FB.

[0140] As an alternative embodiment, the feedback circuit module 6 further includes: a power switch M1; the drain of the power switch M1 is connected to the output terminal of the voltage input module 5 through the primary coil LP; the source of the power switch M1 is connected to the current monitoring port CS; the gate of the power switch M1 is connected to the drive output port DRV.

[0141] The square wave signal Vsw controls the turning on and off of the power switch M1 to complete the energy transfer of the transformer TR.

[0142] Furthermore, the feedback circuit module 6 further includes a current-limiting resistor Rcs; the current-limiting resistor Rcs is connected to the source electrode of the power switch M1 and the other end is grounded.

[0143] UVLO, DRIVER, PWM, and the dual-loop standby control circuit are embedded in a switching power supply controller integrated circuit module 11A. The VDD port of the dual-loop standby control circuit, which is the power supply port, is connected to the power supply VDD of the switching power supply controller integrated circuit module 11A; the EN port of the dual-loop standby control circuit is connected to the EN output terminal of the UVLO of the switching power supply controller integrated circuit 11A; the V STB_VDD port of the dual-loop standby control circuit is connected to the third input terminal V of the DRIVER of the switching power supply controller integrated circuit module 11A STB_VDD ; the V STB_FB port of the dual-loop standby control circuit is connected to the second input terminal V of the DRIVER of the switching power supply controller integrated circuit module 11A STB_FB ; the V FB port of the dual-loop standby control circuit is connected to the input terminal FB of the switching power supply controller integrated circuit 11A and the second input terminal FB of the PWM. The switching power supply controller integrated circuit module 11A includes DLSTB, UVLO, PWM, and DRIVER. The first input terminal CS of the PWM is connected to the first end of the sampling resistor Rcs and the source electrode of the power switch M1. The second input terminal FB of the PWM is connected to the output terminal of the feedback device 12. The output terminal of the PWM is connected to the first input terminal of the drive circuit DRIVER; the second end of the sampling resistor Rcs is grounded; the input terminal of the UVLO is connected to the power supply VDD port of the switching power supply controller integrated circuit module 11A, the first end of the DLSTB, the third input terminal of the PWM, and the fourth end of the DRIVER; the output terminal DRV of the drive circuit DRIVER is externally connected to the gate electrode of the power switch M1; the drain electrode of the power switch M1 is connected to the primary coil Lp of the transformer.

[0144] The switching power supply controller integrated circuit module 11A is coupled to a feedback device 12 provided at the output terminal of the transformer TR to generate a switching signal V SW to adjust the pulse width of the transformer TR through the power switch M1, thereby regulating the energy transfer of the switching power supply 10A; the switching power supply controller integrated circuit module 11A is composed of a dual-loop standby control circuit 50A, a power-on / off enabling circuit 20, a pulse width modulator 30, and a drive circuit 40 coupled together. The dual-loop standby control circuit 50A, the power-on / off enabling circuit 20, the pulse width modulator 30, and the drive circuit 40 are embedded in the controller integrated circuit module 11A to save external components.

[0145] In addition, there is another example of a switching power supply: the switching power supply is a power supply system with a secondary-side feedback method; that is, the dual-loop control circuit can be applied to the secondary-side feedback switching power supply.

[0146] Therefore, when the switching power supply 10A provided in Embodiment 2 is under system heavy load, the input voltage V of the VDD port DD is at a high potential, V DD1 is much greater than vref1 and vref2, and the output V of the first comparator 51 STB_VDD is logic "1", and the signal V after passing through the first inverter 52 STB_VDD_N is logic "0", V STB_VDD and V STB_VDD_N control the first switch M50 to turn on and the second switch M51 to turn off respectively. As a result, the input voltage threshold of the first comparator 51:

[0147] V VDD_REF = vref2 = θ2 × vref.

[0148] When under heavy load, the output V of the feedback device 12 FB is a high voltage, far exceeding the fourth reference voltage vref3 and the fifth reference voltage vref4. As a result, the output signal V after passing through the second comparator 53 FB is logic "1", and the signal V after passing through the second inverter 54 STB_FB is logic "0", V STB_FB_N and V STB_FB control the third switch M52 to turn on and the fourth switch M53 to turn off respectively. As a result, the input voltage threshold of the second comparator 53: STB_FB_N V

[0149] V FB_REF = V FB_IN = vref4 = θ4 × vref.

[0150] When the system, that is, the switching power supply 10A, switches from heavy load to no load, the output V of the feedback device 12 FB The signal voltage changes from high to low. When V FB is lower than V FB_REF = V FB_IN = θ4 × vref, the logic of the output V of the second comparator 53 STB_FB flips to "0". After passing through the second inverter 54, the signal V STB_FB_N is logic "1", and the signals V STB_FB and V STB_FB_N control the third switch M52 to turn off and the fourth switch M53 to turn on respectively. As a result, the input voltage threshold V of the second comparator 53 FB_REF = V FB_OUT = vref3 = θ3 × vref. The V with logic "0" STB_FBVsw is turned off, that is, V FB is lower than V FB_IN After the drive signal Vsw is turned off, the system enters the skip cycle mode and causes the VDD voltage to drop. When the VDD voltage drops below VDD hold1 i.e., when V DD1 drops below vref2:

[0151] V DD1 = β × V DD < V VDD_REF = vref2 = θ2 × vref.

[0152] VDD hold1 = θ2 × vref / β.

[0153] V DD < VDD hold1 .

[0154] V DD1 After being compared by the first comparator 51, the output signal V STB_VDD flips from the initial logic "1" after VDD power-on to logic "0", controlling the switch power supply 10A to forcefully exit the skip cycle mode, and the drive signal Vsw resumes the switching operation. Here, the control priority for V STB_VDD to resume the Vsw switching operation is higher than V STB_FB , but V STB_VDD does not change the logic of V STB_FB , so it can be seen that the skip cycle mode (i.e., no-load standby) control is a dual-loop standby control. These two loops are respectively V DD →V DD1 →V STB_VDD loop and V o →V FB →V STB_FB loop. As a result, V STB_VDD = "0", V STB_VDD_N = "1", the second switch M51 is on, the first switch M50 is off, and V VDD_REF = vref1 = θ1 × vref.

[0155] After the drive signal Vsw is restored, VDD starts to rise. When the VDD voltage is greater than VDD hold2 i.e., when V DD1 rises above vref1, there is

[0156] V DD1 = β × V DD > V VDD_REF = vref1 = θ1 × vref.

[0157] VDD hold2 = θ1 × vref / β.

[0158] V DD >VDD hold2 。

[0159] V DD1 After being compared by the first comparator 51, the output signal V STB_VDD flips from logic "0" to logic "1", and the control right of the skip cycle mode of the switching power supply 10A is given to V FB , and at this time V FB is still lower than V FB_OUT , then V STB_FB is logic "0", and V STB_FB turns off the drive signal Vsw. V STB_VDD ="1", then V STB_VDD_N ="0", the second switch M51 turns off, the first switch M50 turns on, and V VDD_REF =vref2 = θ2×vref.

[0160] Turning off the drive signal Vsw causes the VDD voltage to drop. When the VDD voltage drops below VDD hold1 i.e., when V DD1 drops below vref2, the above control process of VDD is repeated. As a result, VDD fluctuates periodically between VDD hold1 , VDD hold2 until V FB rises above V FB_OUT =V FB_REF =vref3 = θ3×vref, then V STB_FB ="1".

[0161] If V STB_VDD ="0" at this time, then V STB_VDD forces the restoration of the Vsw switch to work; if V STB_VDD ="1", then the control right is given to V STB_FB , then V STB_FB ="1" to restore the Vsw switch to work. Therefore, regardless of the state of VDD, once V STB_FB ="1", the Vsw restores the switch to work, and VDD will continue to rise during V STB_FB ="1".

[0162] The above is a complete working process of the switching power supply based on the dual-loop standby control circuit. The timing waveform of the switching power supply is as shown in Figure 3 The switching power supply 10A containing the dual-loop standby control circuit not only realizes the safety and the working consistency at wide temperatures, but also realizes the minimization of the standby power consumption.

[0163] In addition, the waveform comparison between the switching power supply 10A of the present invention and the traditional switching power supply 10 when the output load switches from heavy load to no load is as follows Figure 3 and Figure 5 shown

[0164] From Figure 5 the waveforms, it can be seen the waveforms of two instances of the traditional switching power supply 10 when the output load switches from heavy load to no load. One instance, STB Mode1, is the waveform of the traditional switching power supply system 10 without the VDD power-down prevention technology. The result shows that after the output load switches from heavy load to no load, the VDD powers down (i.e., VDD < VDD OFF ), resulting in an automatic restart of VDD, and the output voltage Vo oscillates beyond the maximum ripple △Vo requirement of Vo. The other instance, STB Mode2, is the waveform of the traditional switching power supply system 10 with the VDD power-down prevention technology. The result shows that after the output load switches from heavy load to no load, the VDD is stable without power-down, the output voltage Vo is stable and normal, but the Vsw waveform keeps continuously switching, generating serious switching losses, and the standby power consumption of the switching power supply system exceeds the energy efficiency specification range and fails to meet the standby power consumption index requirements.

[0165] From Figure 3 the waveforms, it can be seen that when the output load of the switching power supply 10A provided in Embodiment 2 of the present invention switches from heavy load to no load, due to the dual-loop standby control technology of V DD and V FB , the result shows that there is no power-down of V DD during the heavy-load to no-load switching (i.e., V DD < VDD OFF ), and the ripple of the output voltage Vo is also within the maximum ripple △Vo, meeting the power supply specification requirements. At the same time, it can be seen that the action of Vsw is to close for a long time and then send a few pulses, and then close for a long time and send a few pulses again, working in a cycle of jumping periods. This greatly reduces the total switching losses per unit time. As a result, the switching losses of the system are greatly reduced during no-load standby, and it is very easy to meet the energy efficiency standby power consumption index requirements for the no-load standby power consumption index.

[0166] The advantages of the switching power supply provided in the embodiments of the present invention are as follows

[0167] The embodiments provided by the present invention can be applied to both secondary-side feedback switching power supply systems and primary-side feedback switching power supply systems. The switching power supply systems applying the embodiments of the present invention are significantly superior to other switching power supply systems in terms of safety, low standby power consumption, etc., can save costs for users, and reduce the design difficulty of the switching power supply system.

[0168] In this specification, the various embodiments are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other.

[0169] In this article, specific examples are used to elaborate on the principles and implementation manners of the present invention. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present invention. At the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation on the present invention.

Claims

1. A dual-loop standby control circuit, characterized in that, The control circuit includes: a first voltage dividing module, a second voltage dividing module, a first control module, and a second control module; The input end of the first voltage dividing module is connected to the power supply port; the first voltage dividing module is used to convert the power supply voltage provided by the power supply port into an initial reference voltage and output it, and divide the initial reference voltage to output a first reference voltage, a second reference voltage, a third reference voltage, a fourth reference voltage, and a fifth reference voltage; The second voltage dividing module is connected to the power supply port; the second voltage dividing module is used to divide the power supply voltage to obtain a power supply divided voltage; The first control module includes: a first comparator, a first inverter, a first switch, and a second switch; The first end of the first comparator is connected to the output end of the second voltage dividing module; the second end of the first comparator is respectively connected to the drain of the first switch and the drain of the second switch; the third end of the first comparator is connected to the input end of the first inverter; the third end of the first comparator is also connected to the power supply enabling port to output a power supply port enabling signal; The source of the first switch is connected to the output end of the third reference voltage; the source of the second switch is connected to the output end of the second reference voltage; The fourth end of the first comparator is connected to the output end of the first reference voltage; the fifth end of the first comparator is connected to the setting enabling port; The output end of the first inverter is connected to the gate of the second switch; the gate of the first switch is connected to the power supply enabling port; The second control module includes: a second comparator, a second inverter, a third switch, and a fourth switch; The first end of the second comparator is connected to the feedback port; The second end of the second comparator is respectively connected to the drain of the third switch and the drain of the fourth switch; the third end of the second comparator is connected to the input end of the second inverter; the third end of the second comparator is also connected to the feedback enabling port to output a feedback port enabling signal; The fifth end of the second comparator is connected to the setting enabling port; the fourth end of the second comparator is connected to the output end of the first reference voltage; The source of the fourth switch is connected to the output end of the fourth reference voltage; the source of the third switch is connected to the output end of the fifth reference voltage; the gate of the third switch is connected to the feedback enabling port; The output end of the second inverter is connected to the gate of the fourth switch.

2. The dual-loop standby control circuit according to claim 1, wherein The first voltage dividing module includes: a voltage transformer, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, and a seventh resistor connected in sequence; The voltage transformer is connected to the power supply port; the voltage transformer is used to convert the power supply voltage into an initial reference voltage and divide the initial reference voltage to obtain the first reference voltage; The third resistor is connected to the voltage transformer, and the third resistor is used to divide the first reference voltage to obtain the second reference voltage; The fourth resistor is connected to the third resistor, and the fourth resistor is used to divide the second reference voltage to obtain the third reference voltage; The fifth resistor is connected to the fourth resistor, and the fifth resistor is used to divide the third reference voltage to obtain the fourth reference voltage; The sixth resistor is connected to the fifth resistor, and the sixth resistor is used to divide the fourth reference voltage to obtain the fifth reference voltage; One end of the seventh resistor is connected to the sixth resistor and the other end is grounded.

3. The dual-loop standby control circuit according to claim 1, characterized in that, The second voltage dividing module includes: a first resistor and a second resistor; One end of the first resistor is connected to the power supply port, and the other end of the first resistor is connected to one end of the second resistor; the other end of the second resistor is grounded; the connection end between the first resistor and the second resistor is the output end of the second voltage dividing module.

4. A dual-loop standby switching power supply, characterized in that, The switching power supply includes: a voltage input module, a feedback circuit module, and a controller integrated circuit module; the controller integrated circuit module includes a power-on / off enabling circuit, a driving circuit, a pulse modulator, and the dual-loop standby control circuit according to any one of claims 1-3; The input end of the voltage input module is connected to the input line voltage end, and the output end of the voltage input module is respectively connected to the power supply port and the input end of the feedback circuit module; the output end of the feedback circuit module is respectively connected to the feedback port and the current monitoring port; The input ends of the pulse modulator are respectively connected to the feedback port, the current monitoring port, and the power supply port; the output end of the pulse modulator is connected to the driving circuit; The input end of the power-on / off enabling circuit is connected to the power supply port; the output end of the power-on / off enabling circuit is connected to the set enabling port; The input ends of the driving circuit are respectively connected to the power supply port, the feedback end enabling port, and the power supply end enabling port; the output end of the driving circuit is connected to the driving output port.

5. The dual-loop standby switching power supply according to claim 4, wherein The feedback circuit module includes: a voltage conversion sub-module and a feedback device; The input end of the voltage conversion sub-module is connected to the output end of the voltage input module; the output end of the voltage conversion sub-module is connected to the feedback device; The output end of the feedback device is connected to the feedback port.

6. The dual-loop standby switching power supply according to claim 5, wherein, The feedback circuit module further includes: a power switch tube; The drain of the power switch tube is connected to the output end of the voltage input module through the primary coil; the source of the power switch tube is connected to the current monitoring port; the gate of the power switch tube is connected to the driving output port.

7. The dual-loop standby switching power supply according to claim 6, wherein, The feedback circuit module further includes: a current limiting resistor; One end of the current limiting resistor is connected to the source of the power switch tube and the other end is grounded.

8. The dual-loop standby switching power supply according to claim 6, wherein, The voltage conversion sub-module includes: a transformer, a diode, and a capacitor; The transformer includes a primary coil and a secondary coil; the primary coil is respectively connected to the output end of the voltage input module and the drain of the power switch tube; the secondary coil is respectively connected to the anode of the diode and the capacitor; the cathode of the diode is connected to the capacitor.

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