Synchronous boost converter with input switch and control chip thereof

Abstract

The invention discloses a synchronous boost converter with an input switch and a control chip thereof in the technical field of power management, the synchronous boost converter comprises a synchronous boost converter main body module, a driving module and an input control switch, and the synchronous boost converter main body module is used for boosting direct current voltage in the synchronous boost converter; the driving module is connected with the synchronous boost converter main body module, generates a driving signal and provides the driving signal to the power tube, the rectification MOS tube and the input switch tube; the input control switch is connected to a DG pin of the driving module and comprises a CS amplifier, a turn-off comparator, a surge comparator and a DG charge pump circuit. By adopting the synchronous boost converter with the input switch, not only can the current be limited when the input power supply surges, but also the current path with the output can be completely disconnected from the input end when the load is abnormal and the output voltage needs to be turned off, so that the output voltage is reduced to zero, and the functions of surge current limiting and circuit break protection are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of power management, in particular to a synchronous boost converter with an input switch and a control chip thereof. Background Art

[0002] The boost converter, also known as the BOOST converter, is a typical DC converter circuit, which is widely used in the fields of switching power supplies, DC motor drives, photovoltaic power generation systems, etc. Boost converters can be divided into synchronous boost converters and asynchronous boost converters according to the different rectification methods. The synchronous boost converter uses MOS tube rectification instead of diode rectification, which reduces the forward conduction loss during rectification and obtains higher conversion efficiency, and is more widely used in high-power applications.

[0003] The synchronous boost converter consists of an input capacitor CIN, an energy storage inductor LIN, a power tube QL, a rectifier MOS tube QH and an output capacitor COUT. In a conventional boost topology, whether it is a synchronous boost or an asynchronous boost, the rectifier diode or the body diode of the rectifier MOS tube will be forward-conducted, and the input power can be directly output to the load through the inductor and the rectifier device, that is, the current path between the input and the output cannot be completely shut off, so the output voltage cannot drop to zero volts, which will cause continuous shutdown losses and even damage the load. Summary of the invention

[0004] The purpose of the present invention is to provide a synchronous boost converter with an input switch and a control chip thereof, which can limit the current size when a surge occurs in the input power supply, and can also completely disconnect the current path from the input end to the output when the load is abnormal and the output voltage needs to be shut down, so that the output voltage drops to zero.

[0005] To achieve the above object, the present invention provides the following technical solutions: In a first aspect, the present invention provides a synchronous boost converter with an input switch, comprising a synchronous boost converter main module, a driving module and an input control switch, wherein the synchronous boost converter main module is used to increase the DC voltage in the synchronous boost converter; the driving module is connected to the synchronous boost converter main module, and generates a driving signal to provide to a power tube, a rectifier MOS tube and an input switch tube; the input control switch is connected to a DG pin of the driving module, and the input control switch comprises a CS amplifier, a shutdown comparator, a surge comparator and a DG charge pump circuit, wherein the DG charge pump circuit uses a pull-up current source to charge the DG pin, and the DG pin voltage is within a threshold range by cooperating with the limiting effect of a voltage regulator diode, and when the sampling current exceeds the threshold voltage, the surge comparator turns on the pull-down current source to discharge the DG pin to a surge current limiting stable point; if the output voltage of the CS amplifier exceeds the upper threshold, the shutdown comparator will output a high level to reduce the input current to 0 and discharge the inductive current for circuit breaker protection.

[0006] As a further solution of the present invention: the driving module includes a VIN pin, a CSP pin, a CSN pin, a DG pin and a DS pin.

[0007] As a further solution of the present invention: the non-inverting input terminal and the inverting input terminal of the CS amplifier are connected to the CSP pin and the CSN pin in sequence, the inverting input terminal of the shutdown comparator and the inverting input terminal of the surge comparator are respectively connected to the threshold voltage, the output terminal of the CS amplifier is connected to the non-inverting input terminal of the shutdown comparator and the surge comparator, the output terminal of the surge comparator is connected to the DG charge pump circuit, and the input control switch is used to limit the surge current generated by the synchronous boost converter and shut down the output voltage; The output end of the shutdown comparator is connected to the gate of the first MOS tube, the source of the first MOS tube is grounded, the drain of the first MOS tube is connected to the DG pin, the DG pin is connected to the cathodes of the first Zener diode and the second Zener diode in sequence, the anode of the first Zener diode is connected to the DS pin, the anode of the second Zener diode is connected to the VIN pin, and the first Zener diode and the second Zener diode are used to stabilize the voltage at the DG pin; A VGS detection circuit is connected between the drain of the first MOS tube and the DS pin.

[0008] As a further solution of the present invention: the DG charge pump circuit includes a pull-up current source and a pull-down current source, one end of the pull-down current source is connected to the cathode of the third voltage zener diode, the anode of the third voltage zener diode is connected to the output end of the pull-up current source, the output end of the surge comparator is connected to the output end of the pull-down current source, and the DG charge pump circuit charges the DG pin through the pull-up current source to put the input switch tube in the on state.

[0009] As a further solution of the present invention: the amplification gain of the CS amplifier is 10.

[0010] As a further solution of the present invention: the main module of the synchronous boost converter includes an input capacitor, an energy storage inductor, a power tube, a rectifier MOS tube and an output capacitor, one end of the input capacitor is connected to the input end of the synchronous boost converter, the other end of the input capacitor is grounded, one end of the energy storage inductor and the source of the rectifier MOS tube are both connected to the SW pin of the driving module, the drain of the rectifier MOS tube is connected to the output end, and the gate of the rectifier MOS tube is connected to the HO pin of the driving module.

[0011] As a further solution of the present invention: the synchronous boost converter further comprises an input control module connected to the pin of the driving module, the input control module being used to sample the input current of the main module of the synchronous boost converter; The input control module includes an input current sampling resistor, an input switch tube and a freewheeling diode. One end of the input current sampling resistor is connected to the input end, the other end of the current sampling resistor is connected to the drain of the input switch tube, the source of the input switch tube is connected to one end of the energy storage inductor, the gate of the input switch tube is connected to the DG pin, the cathode of the freewheeling diode is connected to the source of the input switch tube, the anode of the freewheeling diode is grounded, and the freewheeling diode is used to discharge the stored electric energy of the energy storage inductor so that the output voltage V OUT drops to 0V.

[0012] As a further solution of the present invention: the synchronous boost converter further includes an undervoltage point setting module, the undervoltage point setting module is used to set the undervoltage point of the input voltage; The undervoltage point setting module includes a first voltage-dividing resistor and a second voltage-dividing resistor, one end of the first voltage-dividing resistor is grounded, the other end of the first voltage-dividing resistor and one end of the second voltage-dividing resistor are both connected to the UVLO pin of the driving module, and the other end of the second voltage-dividing resistor is connected to the input end.

[0013] As a further solution of the present invention: the synchronous boost converter further comprises a compensation signal generating module, the compensation signal generating module is used to generate a slope compensation signal of the synchronous boost converter; The compensation signal generating module is a third resistor with one end grounded and the other end connected to the constant voltage output pin SLOPE of the driving module. The third resistor cooperates with the constant voltage output pin SLOPE to produce an internal slope compensation signal.

[0014] As a further solution of the present invention: the synchronous boost converter further comprises a withstand time setting module, the withstand time setting module is used to set the withstand time of cycle-by-cycle current limiting; The withstand time setting module is a first capacitor, one end of the first capacitor is connected to the RES pin of the driving module, and the other end of the first capacitor is grounded.

[0015] As a further solution of the present invention: the synchronous boost converter further includes a soft start time setting unit, the soft start time setting unit is used to set the soft start time of the driving module; The soft start time setting unit is a second capacitor, one end of the second capacitor is connected to the SS pin of the driving module, and the other end of the second capacitor is grounded.

[0016] As a further solution of the present invention: the synchronous boost converter further comprises an internal clock generating module, the internal clock generating module being used to set the internal clock frequency of the driving module; The internal clock generation module is a fourth resistor with one end connected to the constant voltage output pin RT of the driving module and the other end grounded. The fourth resistor cooperates with the constant voltage output pin RT to set the frequency of the internal clock of the driving module.

[0017] As a further solution of the present invention: the synchronous boost converter further includes a working mode setting module, the working mode setting module is used to set the working mode of the driving module; The working modes include diode emulation mode and forced PWM mode. When the driving module works in diode emulation mode, the MODE pin of the driving module is grounded to prevent the output voltage from flowing back to the input. When the driving module works in forced PWM mode, the MODE pin of the driving module is connected to VCC to speed up the load response speed of the driving module.

[0018] As a further solution of the present invention: the synchronous boost converter further includes a constant voltage control loop module and a loop compensation module, the constant voltage control loop module is used to set the output voltage, and the loop compensation module is used to compensate for the stability of the loop in the constant voltage control loop module; The constant voltage control loop module includes a third voltage-dividing resistor and a fourth voltage-dividing resistor, one end of the third voltage-dividing resistor is connected to the FB pin of the driving module, the other end of the third voltage-dividing resistor is grounded, and the third voltage-dividing resistor and the fourth voltage-dividing resistor are used to sample the output voltage to form a constant voltage control loop to set the output voltage; The loop compensation module includes a third capacitor and a fifth resistor, one end of the third capacitor is connected to the COMP pin of the driving module, the other end of the third capacitor is connected to one end of the fifth resistor, and the other end of the fifth resistor is connected to the FB pin of the driving module.

[0019] As a further solution of the present invention: the synchronous boost converter also includes a filtering module, the filtering module is a fourth capacitor with one end grounded and the other end connected to the VCC pin of the driving module, the fourth capacitor is used to filter the low-voltage power supply pin VCC pin, a bootstrap diode is connected between the VCC pin and the BST pin of the driving module, a bootstrap capacitor is connected between the BST pin and the SW pin, and the bootstrap diode is used to charge the bootstrap capacitor to complete the power supply to the high-side output.

[0020] In a second aspect, the present invention further provides a control chip, comprising a synchronous boost converter with an input switch as described in the above solution.

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1. In the present invention, by adopting a synchronous boost converter with an input switch, not only can the current be limited when a surge occurs in the input power supply, but also when the load is abnormal and the output voltage needs to be shut down, the current path from the input end to the output is completely disconnected, so that the output voltage drops to zero, thereby realizing the functions of surge current limiting and circuit breaker protection.

[0022] 2. In the present invention, the output of the synchronous boost converter is completely shut down and reduced to 0V by using an input switch. On the one hand, the shutdown power consumption of the synchronous boost converter is reduced, and on the other hand, the safety and reliability of the synchronous boost converter can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the module connection diagram of the present invention; Figure 2 is a circuit diagram of a synchronous boost converter of the present invention; Figure 3 This is a functional block diagram of the input switch control of the present invention; Figure 4 is a schematic diagram of the startup waveform of the synchronous boost converter of the present invention; Figure 5 This is a block diagram of the control chip of the present invention.

[0024] In the figure: 1. main module of synchronous boost converter; 2. input control module; 3. drive module; 301. input control switch; 4. undervoltage point setting module; 5. compensation signal generating module; 6. withstand time setting module; 7. soft start time setting unit; 8. internal clock generating module; 9. working mode setting module; 10. constant voltage control loop module; 11. loop compensation module; 12. filter module. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Example: like Figure 1As shown, in an embodiment of the present invention, a synchronous boost converter with an input switch is provided, including a synchronous boost converter main module 1, a drive module 3 and an input control switch 301. The synchronous boost converter main module 1 is used to increase the DC voltage in the synchronous boost converter; the drive module 3 is connected to the synchronous boost converter main module 1, and generates a drive signal to provide to the power tube Q L , Rectifier MOS tube Q H and input switch tube Q D。 like Figure 3 As shown, the input control switch 301 is connected to the DG pin of the driving module 3. The input control switch 301 includes a CS amplifier, a shutdown comparator, a surge comparator and a DG charge pump circuit. The DG charge pump circuit uses a pull-up current source to charge the DG pin. The voltage of the DG pin is within the threshold range by cooperating with the limiting effect of the voltage regulator diode. When the sampling current exceeds the threshold voltage, the surge comparator turns on the pull-down current source to discharge the DG pin to the surge current limiting stable point. If the output voltage of the CS amplifier exceeds the upper threshold, the shutdown comparator will output a high level to reduce the input current to 0 and discharge the inductive current for circuit breaker protection.

[0027] Preferably, Figure 2 As shown, the driving module 3 is a BST7970 driving chip, and the driving module 3 includes a VIN pin, a CSP pin, a CSN pin, a DG pin and a DS pin.

[0028] Preferably, Figure 2 As shown, the non-inverting input terminal and the inverting input terminal of the CS amplifier are connected to the CSP pin and the CSN pin in sequence, the inverting input terminals of the shutdown comparator and the surge comparator are connected to the threshold voltage respectively, the output terminal of the CS amplifier is connected to the non-inverting input terminals of the shutdown comparator and the surge comparator, the output terminal of the surge comparator is connected to the DG charge pump circuit, and the input control switch 301 is used to limit the surge current generated by the synchronous boost converter and shut down the output voltage; The output end of the shutdown comparator is connected to the gate of the first MOS tube NM1, the source of the first MOS tube NM1 is grounded, the drain of the first MOS tube NM1 is connected to the DG pin, the DG pin is connected to the cathodes of the first Zener diode DZ1 and the second Zener diode DZ2 in sequence, the anode of the first Zener diode DZ1 is connected to the DS pin, the anode of the second Zener diode DZ2 is connected to the VIN pin, and the first Zener diode DZ1 and the second Zener diode DZ2 are used to stabilize the voltage at the DG pin; A VGS detection circuit is connected between the drain of the first MOS tube NM1 and the DS pin.

[0029] Preferably, Figure 3As shown, the DG charge pump circuit includes a pull-up current source and a pull-down current source, one end of the pull-down current source is connected to the cathode of the third voltage zener diode, the anode of the third voltage zener diode is connected to the output end of the pull-up current source, the output end of the surge comparator is connected to the output end of the pull-down current source, and the DG charge pump circuit charges the DG pin through the pull-up current source to make the input switch tube Q D In the on state.

[0030] Preferably, Figure 3 As shown, the gain of the CS amplifier is 10.

[0031] During normal operation, the DG charge pump circuit charges DG with a 25μA pull-up current source, and the input switch tube Q D It is in a fully on state, and the voltage at the DG pin is limited by the first Zener diode DZ1 and the second Zener diode DZ2, and will not exceed (VIN pin voltage + 11V) or DS pin voltage + 16V; then the input current sampling resistor R CS , CSP pin and CSN pin complete the sampling of input current and convert the sampling signal I IN *R CS After being amplified by the CS amplifier with a gain of 10, V SENSE1 signal, i.e. 10*I IN *R CS ; If 1 signal V SENSE1 When the voltage exceeds 1.1V, the surge current limiting function will be triggered. The surge comparator will output a high level and turn on the 95μA pull-down current source. The DG pin voltage will discharge with a pull-down current of 95μA-25μA=70μA, and the input switch tube Q D The current capability is reduced, and the input current I IN Affected by the input switch tube Q D The current is reduced due to the limitation and finally stabilized at the surge current limit point [1.1V / 10*R CS ]; If the load is abnormal and the input current I IN Rapidly increases, before the surge current limiting is established stably, V SENSE1 If the voltage exceeds 1.6V, that is, I IN >[1.6V / 10*R CS ], the circuit breaker protection will be triggered, the comparator output will be turned off, the first MOS tube NM1 will be turned on and pulled down, and the input switch tube Q will be quickly turned off with a peak value of 0.3A. D , so that the input current I IN Rapidly drops to 0, and the inductor current I L The freewheeling diode D F Discharge slowly from the input I IN The current value is reduced to 0.

[0032] Preferably, Figure 2 As shown, the synchronous boost converter main module 1 includes an input capacitor , Energy Storage Inductor , power tube , Rectifier MOS tube and output capacitor , input capacitance One end of the synchronous boost converter is connected to the input terminal, and the input capacitor The other end of the energy storage inductor is grounded. One end of the rectifier MOS tube The source of the MOSFET is connected to the SW pin of the driver module 3. The drain of the rectifier MOS tube is connected to the output terminal. The gate is connected to the HO pin of driver module 3.

[0033] Preferably, Figure 1 As shown, the synchronous boost converter further includes an input control module 2 connected to the pin of the driving module 3, and the input control module 2 is used to sample the input current of the synchronous boost converter main module 1; like Figure 2 As shown, the input control module 2 includes an input current sampling resistor R CS , Input switch tube Q D and freewheeling diode D F , input current sampling resistor R CS One end is connected to the input end, and the current sampling resistor R CS The other end is connected to the input switch tube Q D The drain of the input switch tube Q D The source connected energy storage inductor One end of the input switch tube Q D The gate of the diode is connected to the DG pin, and the freewheeling diode D F The negative pole of the input switch tube Q D The source of the freewheeling diode D F The positive pole of the freewheeling diode D is grounded. F Used to discharge energy storage inductor The stored electrical energy makes the output voltage V OUT drops to 0V.

[0034] Preferably, Figure 1 As shown, the synchronous boost converter further includes an undervoltage point setting module 4, and the undervoltage point setting module 4 is used to set the undervoltage point of the input voltage; like Figure 2 As shown, the undervoltage point setting module 4 includes a first voltage dividing resistor R UV1 and the second voltage divider resistor R UV2 , the first voltage divider resistor RUV1 One end of the first voltage divider resistor R UV1 The other end of the second voltage divider resistor R UV2 One end of each resistor is connected to the UVLO pin of the driver module 3, and the second voltage divider resistor R UV2 Connect the other end of the input terminal.

[0035] Preferably, Figure 1 As shown, the synchronous boost converter further includes a compensation signal generating module 5, and the compensation signal generating module 5 is used to generate a slope compensation signal of the synchronous boost converter; like Figure 2 As shown, the compensation signal generating module 5 is a third resistor R with one end grounded and the other end connected to the constant voltage output pin SLOPE of the driving module 3. SLOPE , the third resistor R SLOPE Cooperate with the constant voltage output pin SLOPE to produce the internal slope compensation signal.

[0036] Preferably, Figure 1 As shown, the synchronous boost converter further includes a withstand time setting module 6, which is used to set the withstand time of cycle-by-cycle current limiting; like Figure 2 As shown, the withstand time setting module 6 is a first capacitor C RES , the first capacitor C RES One end of the first capacitor C is connected to the RES pin of the driving module 3. RES The other end is grounded.

[0037] Preferably, Figure 1 As shown, the synchronous boost converter further includes a soft start time setting unit 7, and the soft start time setting unit 7 is used to set the soft start time of the driving module 3; like Figure 2 As shown, the soft start time setting unit 7 is a second capacitor C SS , the second capacitor C SS One end of the second capacitor C is connected to the SS pin of the driver module 3. SS The other end is grounded.

[0038] Preferably, Figure 1 As shown, the synchronous boost converter further includes an internal clock generating module 8, and the internal clock generating module 8 is used to set the internal clock frequency of the driving module 3; like Figure 2 As shown, the internal clock generation module 8 is a fourth resistor R connected to the constant voltage output pin RT of the driving module 3 at one end and grounded at the other end. T , the fourth resistor R T The frequency of the internal clock of the driving module 3 is set in conjunction with the constant voltage output pin RT.

[0039] Preferably, Figure 1 As shown, the synchronous boost converter further includes a working mode setting module 9 , and the working mode setting module 9 is used to set the working mode of the driving module 3 .

[0040] Preferably, the working modes include diode emulation mode and forced PWM mode. When the driving module 3 works in the diode emulation mode, the MODE pin of the driving module 3 is grounded to prevent the output voltage from flowing back to the input. When the driving module 3 works in the forced PWM mode, the MODE pin of the driving module 3 is connected to VCC to speed up the load response speed of the driving module 3.

[0041] Preferably, Figure 1 As shown, the synchronous boost converter further includes a constant voltage control loop module 10 and a loop compensation module 11, the constant voltage control loop module 10 is used to set the output voltage, and the loop compensation module 11 is used to compensate for the stability of the loop in the constant voltage control loop module 10; like Figure 2 As shown, the constant voltage control loop module 10 includes a third voltage dividing resistor R FB1 And the fourth voltage divider resistor R FB2 , the third voltage divider resistor R FB1 One end of the resistor is connected to the FB pin of the driver module 3, and the third voltage divider resistor R FB1 The other end of the third voltage divider resistor R FB1 And the fourth voltage divider resistor R FB2 Used to sample the output voltage to form a constant voltage control loop to set the output voltage; The loop compensation module 11 includes a third capacitor C COMP and the fifth resistor R COMP , the third capacitor C COMP One end of the third capacitor C is connected to the COMP pin of the driver module 3. COMP The other end is connected to the fifth resistor R COMP One end of the fifth resistor R COMP The other end is connected to the FB pin of the driver module 3.

[0042] Preferably, Figure 1 As shown, the synchronous boost converter further includes a filter module 12, such as Figure 2 As shown, the filter module 12 is a fourth capacitor C with one end grounded and the other end connected to the VCC pin of the driving module 3. VCC , the fourth capacitor C VCC It is used to filter the low voltage power supply pin VCC. A bootstrap diode D is connected between the VCC pin and the BST pin of the driver module 3. BST , a bootstrap capacitor C is connected between the BST pin and the SW pin BST , bootstrap diode DBST For the bootstrap capacitor C BST Charge to complete the power supply to the high-side output.

[0043] The working principle of the converter is: when powered on, the driver module 3 is in the off state, and the voltage of the UVLO pin of the driver module 3 gradually increases with the increase of the VIN pin voltage. When the increased pin voltage exceeds the off threshold of 0.4V, the driver module 3 enters the standby state, and the VCC power supply voltage is gradually formed inside it; The modules connected by the pins of the driver module 3 start to work. At this time, the RT pin of the driver module 3 outputs a constant 1.2V voltage. On the other hand, the internal clock signal of the driver module 3 starts to be generated until the voltage value of the UVLO pin exceeds the standby threshold point of 1.2V. The driver module 3 enters the normal working state and starts the soft start process. The waveform generated by this process is as follows: Figure 4 As shown; When the driver module 3 works normally, the input switch tube Q is turned on first. D , as the DG pin outputs a 25μA pull-up current, the input switch Q D The gate-source voltage VGS gradually rises until it is fully turned on. The input power supply will directly connect the output capacitor C with a large current. OUT Charging triggers the surge current limiting protection, which is done by switching the input switch Q D The control limits the charging current to the surge current limit point. When the output voltage rises to close to the input voltage, the driver module 3 is out of surge current limiting protection, and the input switch tube Q D The VGS voltage continues to rise and then reaches the VGS detection point. The internal VGS_Detect signal flips, turning on the soft-start charging current of the SS pin, and the voltage of the SS pin begins to rise. When the voltage of the SS pin exceeds the voltage of the FB pin, the output LO starts to send out a PWM waveform to drive the power tube Q L The converter works according to the principle of synchronous boost circuit, and the output capacitor C OUT Continue charging until the voltage of the SS pin reaches 1.2V, at which point the duty cycle is fully expanded, the constant voltage loop is fully established, and the converter starts to supply power normally; During normal operation of the converter, if a load fault occurs, the circuit breaker protection mechanism of the driver module 3 is triggered, and the DG pin will quickly discharge to the DS pin, allowing the input switch tube Q D Turn off, energy storage inductor L IN The stored energy will flow through the freewheeling diode D F Discharge, at this time, the output voltage V OUT will drop to 0V.

[0044] In a second aspect, the present invention further provides a control chip, comprising a synchronous boost converter with an input switch as described above.

[0045] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A synchronous boost converter with an input switch, characterized in that: include: a synchronous boost converter main body module, the synchronous boost converter main body module being used to boost the DC voltage within the synchronous boost converter; A driving module, the driving module is connected to the synchronous boost converter main module and generates a driving signal; An input control switch, the input control switch is connected to the DG pin of the driving module, the input control switch comprises a CS amplifier, a shutdown comparator, a surge comparator and a DG charge pump circuit; The DG charge pump circuit uses a pull-up current source to charge the DG pin, and the DG pin voltage is kept within the threshold range by cooperating with the limiting effect of the voltage regulator diode. When the sampling current exceeds the threshold voltage, the surge comparator turns on the pull-down current source to discharge the DG pin to the surge current limiting stable point; if the output voltage of the CS amplifier exceeds the upper threshold, the shutdown comparator will output a high level to reduce the input current to 0 and discharge the inductive current for circuit breaker protection.

2. The synchronous boost converter with input switch according to claim 1, characterized in that: The driving module includes a VIN pin, a CSP pin, a CSN pin, a DG pin and a DS pin.

3. The synchronous boost converter with input switch according to claim 2, characterized in that: The non-inverting input terminal and the inverting input terminal of the CS amplifier are connected to the CSP pin and the CSN pin in sequence, the inverting input terminal of the shutdown comparator and the inverting input terminal of the surge comparator are connected to the threshold voltage respectively, the output terminal of the CS amplifier is connected to the non-inverting input terminal of the shutdown comparator and the surge comparator, the output terminal of the surge comparator is connected to the DG charge pump circuit, and the input control switch is used to limit the surge current generated by the synchronous boost converter and shut down the output voltage; The output end of the shutdown comparator is connected to the gate of the first MOS tube, the source of the first MOS tube is grounded, the drain of the first MOS tube is connected to the DG pin, the DG pin is connected to the cathodes of the first Zener diode and the second Zener diode in sequence, the anode of the first Zener diode is connected to the DS pin, the anode of the second Zener diode is connected to the VIN pin, and the first Zener diode and the second Zener diode are used to stabilize the voltage at the DG pin; A VGS detection circuit is connected between the drain of the first MOS tube and the DS pin.

4. The synchronous boost converter with input switch according to claim 1, characterized in that: The DG charge pump circuit includes a pull-up current source and a pull-down current source, one end of the pull-down current source is connected to the cathode of the third voltage zener diode, the anode of the third voltage zener diode is connected to the output end of the pull-up current source, the output end of the surge comparator is connected to the output end of the pull-down current source, and the DG charge pump circuit charges the DG pin through the pull-up current source to put the input switch tube in the on state.

5. The synchronous boost converter with input switch according to claim 4, characterized in that: The amplification gain of the CS amplifier is 10.

6. The synchronous boost converter with input switch according to claim 5, characterized in that: The main module of the synchronous boost converter includes an input capacitor, an energy storage inductor, a power tube, a rectifier MOS tube and an output capacitor. One end of the input capacitor is connected to the input end of the synchronous boost converter, and the other end of the input capacitor is grounded. One end of the energy storage inductor and the source of the rectifier MOS tube are both connected to the SW pin of the driving module, the drain of the rectifier MOS tube is connected to the output end, and the gate of the rectifier MOS tube is connected to the HO pin of the driving module.

7. The synchronous boost converter with input switch according to claim 1, characterized in that: The synchronous boost converter further comprises an input control module connected to the pin of the driving module, the input control module being used to sample the input current of the main module of the synchronous boost converter; The input control module includes an input current sampling resistor, an input switch tube and a freewheeling diode. One end of the input current sampling resistor is connected to the input end, the other end of the current sampling resistor is connected to the drain of the input switch tube, the source of the input switch tube is connected to one end of the energy storage inductor, the gate of the input switch tube is connected to the DG pin, the cathode of the freewheeling diode is connected to the source of the input switch tube, the anode of the freewheeling diode is grounded, and the freewheeling diode is used to discharge the stored electric energy of the energy storage inductor so that the output voltage V OUT drops to 0V.

8. The synchronous boost converter with input switch according to claim 1, characterized in that: The synchronous boost converter further comprises an undervoltage point setting module, the undervoltage point setting module being used to set an undervoltage point of the input voltage; The undervoltage point setting module includes a first voltage-dividing resistor and a second voltage-dividing resistor, one end of the first voltage-dividing resistor is grounded, the other end of the first voltage-dividing resistor and one end of the second voltage-dividing resistor are both connected to the UVLO pin of the driving module, and the other end of the second voltage-dividing resistor is connected to the input end.

9. The synchronous boost converter with input switch according to claim 1, characterized in that: The synchronous boost converter further comprises a compensation signal generating module, the compensation signal generating module being used to generate a slope compensation signal of the synchronous boost converter; The compensation signal generating module is a third resistor with one end grounded and the other end connected to the constant voltage output pin SLOPE of the driving module. The third resistor cooperates with the constant voltage output pin SLOPE to produce an internal slope compensation signal.

10. The synchronous boost converter with input switch according to claim 1, characterized in that: The synchronous boost converter further comprises a withstand time setting module, the withstand time setting module is used to set the withstand time of cycle-by-cycle current limiting; The withstand time setting module is a first capacitor, one end of the first capacitor is connected to the RES pin of the driving module, and the other end of the first capacitor is grounded.

11. The synchronous boost converter with input switch according to claim 1, characterized in that: The synchronous boost converter further comprises a soft start time setting unit, which is used to set the soft start time of the driving module; The soft start time setting unit is a second capacitor, one end of the second capacitor is connected to the SS pin of the driving module, and the other end of the second capacitor is grounded.

12. The synchronous boost converter with input switch according to claim 1, characterized in that: The synchronous boost converter further comprises an internal clock generating module, the internal clock generating module being used to set the internal clock frequency of the driving module; The internal clock generation module is a fourth resistor with one end connected to the constant voltage output pin RT of the driving module and the other end grounded. The fourth resistor cooperates with the constant voltage output pin RT to set the frequency of the internal clock of the driving module.

13. The synchronous boost converter with input switch according to claim 1, characterized in that: The synchronous boost converter further comprises an operating mode setting module, the operating mode setting module being used to set the operating mode of the driving module; The working modes include diode emulation mode and forced PWM mode. When the driving module works in diode emulation mode, the MODE pin of the driving module is grounded to prevent the output voltage from flowing back to the input. When the driving module works in forced PWM mode, the MODE pin of the driving module is connected to VCC to speed up the load response speed of the driving module.

14. The synchronous boost converter with input switch according to claim 1, characterized in that: The synchronous boost converter further comprises a constant voltage control loop module and a loop compensation module, the constant voltage control loop module is used to set the output voltage, and the loop compensation module is used to compensate for the stability of the loop in the constant voltage control loop module; The constant voltage control loop module includes a third voltage-dividing resistor and a fourth voltage-dividing resistor, one end of the third voltage-dividing resistor is connected to the FB pin of the driving module, the other end of the third voltage-dividing resistor is grounded, and the third voltage-dividing resistor and the fourth voltage-dividing resistor are used to sample the output voltage to form a constant voltage control loop to set the output voltage; The loop compensation module includes a third capacitor and a fifth resistor, one end of the third capacitor is connected to the COMP pin of the driving module, the other end of the third capacitor is connected to one end of the fifth resistor, and the other end of the fifth resistor is connected to the FB pin of the driving module.

15. The synchronous boost converter with input switch according to claim 1, characterized in that: The synchronous boost converter also includes a filtering module, which is a fourth capacitor with one end grounded and the other end connected to the VCC pin of the driving module. The fourth capacitor is used to filter the low-voltage power supply pin VCC pin. A bootstrap diode is connected between the VCC pin and the BST pin of the driving module. A bootstrap capacitor is connected between the BST pin and the SW pin. The bootstrap diode is used to charge the bootstrap capacitor to complete the power supply to the high-side output.

16. A control chip, characterized in that: A synchronous boost converter with an input switch comprising any one of claims 1-15.

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