Isolation driving chip and switching power supply

Abstract

The utility model provides an isolation driving chip and a switching power supply, the isolation driving chip comprises an isolation power supply circuit, a primary side signal processing circuit, a signal isolation circuit and a secondary side driving circuit, and the isolation power supply circuit and the signal isolation circuit are respectively and electrically connected with the primary side signal processing circuit and the secondary side driving circuit. And the secondary side driving circuit is electrically connected with an external power switch tube. Through the implementation of the utility model, the isolation power supply circuit is packaged to the isolation driving chip, the problem of interference caused by long wiring can be avoided, the feedback control and under-voltage protection circuit is added in the isolation power supply circuit, the output voltage can be changed by an external adjusting circuit, the driving requirements of different power switch tubes can be met, and the reliability of the driving circuit is improved. By adding the desaturation detection circuit, the Miller clamping circuit and the overload protection circuit in the secondary side driving circuit, an external driving protection circuit can be reduced, the structural design of an application circuit is simplified, and the driving reliability of a product is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of power electronics, in particular to an isolation drive chip and a switching power supply. Background Art

[0002] In power electronic products, insulated gate bipolar transistors (IGBTs) and insulated gate field effect transistors (MOSFETs) are important power switching devices. The reliability and convenience of their driving and driving protection will directly affect the reliability of the entire product. Especially in situations where isolated driving is required, the isolated power supply mode on the driving side will have an impact on the driving circuit layout design and driving reliability of IGBT and MOSFET. The isolated driving chips of IGBT or MOSFET in related technologies only include functional modules such as primary signal processing, signal isolation, and driving amplification, and require additional power control chips to provide isolated power supply for the driving chips. In this way, when designing the isolated driving of IGBT or MOSFET, in addition to the isolated driving chip and the driving protection circuit, the isolated power supply on the driving side needs to be designed separately. The entire driving circuit design is complex and costly, the PCB layout wiring is long, it is easy to introduce interference oscillation, the driving reliability is poor, and different IGBTs and MOSFETs usually have different driving voltage requirements, and the over-voltage and under-voltage protection points on the driving side of the isolated driving chip in related technologies are not adjustable. Therefore, the driving chips in related technologies are difficult to adapt to IGBTs or MOSFETs with various power requirements. Utility Model Content

[0003] The utility model provides an isolation driver chip and a switching power supply, aiming to solve the problem in the related art that the isolation driver chip is difficult to adapt to various driving voltage requirements, the power switch device and the driving circuit design are relatively complex and the reliability is low.

[0004] In order to solve the above technical problems, the first aspect of the utility model provides an isolated driving chip, including: an isolated power supply circuit, a primary signal processing circuit, a signal isolation circuit and a secondary driving circuit, the isolated power supply circuit and the signal isolation circuit are electrically connected to the primary signal processing circuit and the secondary driving circuit respectively, and the secondary driving circuit is used to be electrically connected to an external power switch tube; the secondary driving circuit includes an output control chip, a desaturation detection circuit, a Maitreya clamp circuit, and an overload protection circuit, the desaturation detection circuit, the Maitreya clamp circuit, and the overload protection circuit all include a comparison circuit, each of the comparison circuits is electrically connected to the output control chip and the power switch tube respectively, the isolated power supply circuit includes a feedback control circuit and an undervoltage protection circuit, the feedback control circuit is used to be electrically connected to an external feedback regulation circuit, and the undervoltage protection circuit is electrically connected to the secondary driving circuit and is used to be electrically connected to an external undervoltage protection regulation circuit.

[0005] Furthermore, the isolated power supply circuit also includes a power supply control chip, a first comparator and a switch control circuit; the first end of the first comparator is used to be electrically connected to an external enable control signal generator, the second end of the first comparator is electrically connected to a first reference signal generator, the power supply end of the power supply control chip is electrically connected to an external power supply, the feedback control circuit is electrically connected to the power supply control chip, one end of the switch control circuit is used to be electrically connected to an external transformer circuit, and the other end of the switch control circuit is electrically connected to the power supply control chip.

[0006] Furthermore, the isolated power supply circuit also includes a soft start circuit and an oscillator, and the soft start circuit and the oscillator are both electrically connected to the power control chip.

[0007] Furthermore, the desaturation detection circuit also includes a current source, a second switch tube and a second common-mode amplifier, and the comparison circuit of the desaturation detection circuit includes a third comparator; the first end of the third comparator is electrically connected to the output control chip, the second end of the third comparator is electrically connected to the drain of the power switch tube, the third end of the third comparator is electrically connected to the second reference signal generator, the second common-mode amplifier is electrically connected to the output control chip and the first end of the second switch tube respectively, the second end of the second switch tube is electrically connected to the second end of the third comparator, the third end of the second switch tube is grounded, and the current source is electrically connected to the second end of the third comparator and the power supply end of the secondary drive circuit respectively.

[0008] Furthermore, the Maitreya clamp circuit also includes a third switch tube and a third common-mode amplifier. The comparison circuit of the Maitreya clamp circuit includes a fourth comparator. The first end of the fourth comparator is electrically connected to the output control chip, the second end of the fourth comparator is electrically connected to the gate of the power switch tube, the third end of the fourth comparator is electrically connected to a third reference signal generator, the third common-mode amplifier is electrically connected to the output control chip and the first end of the third switch tube respectively, the second end of the third switch tube is electrically connected to the second end of the fourth comparator, and the third end of the third switch tube is grounded.

[0009] Furthermore, the overload protection circuit also includes a power supply chip, and the comparison circuit of the overload protection circuit includes a fifth comparator; the power supply chip is used to be electrically connected to an external temperature sampling circuit or a current sampling circuit, the first end of the fifth comparator is electrically connected to the output control chip, the second end of the fifth comparator is used to be electrically connected to the temperature sampling circuit or the current sampling circuit, and the third end of the fifth comparator is electrically connected to a fourth reference signal generator.

[0010] A second aspect of the utility model provides a switching power supply, comprising the isolation driver chip as described in the first aspect of the utility model.

[0011] From the above description, it can be seen that the utility model avoids the problem of interference introduced by long wiring of the isolated drive circuit by encapsulating the isolated power supply circuit into the isolated drive chip, and by adding feedback control and undervoltage protection circuits in the isolated power supply circuit, the output voltage can be changed through an external adjustment circuit to adapt to the driving needs of different power switch tubes. In addition, by adding desaturation detection circuits, Maitreya clamping circuits, and overload protection circuits, the external drive protection circuit can be reduced to a certain extent, simplifying the internal circuit structure design of the product and improving the driving reliability of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram of the structure of an isolation driver chip according to an embodiment of the utility model;

[0013] Figure 2 This is a circuit schematic diagram of an isolation driver chip according to an embodiment of the utility model;

[0014] Figure 3 This is a schematic diagram of the structure of a practical application of an isolation driver chip according to an embodiment of the utility model;

[0015] Figure 4 This is a circuit schematic diagram of another isolation driver chip according to an embodiment of the utility model. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical scheme and advantages of the utility model clearer, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. It should be understood that the specific embodiments described herein are only used to explain the utility model and are not used to limit the utility model. In addition, the technical features involved in the various embodiments of the utility model described below can be combined with each other as long as they do not conflict with each other.

[0017] In the related art, since the isolation driver chip is difficult to adapt to the power switch devices with various power requirements and the drive circuit design is relatively complex and has low reliability, the embodiment of the utility model provides an isolation driver chip.

[0018] like Figure 1 The figure shows a schematic diagram of the structure of an isolation driver chip provided by an embodiment of the utility model, wherein the isolation driver chip comprises: an isolation power supply circuit 100, a primary signal processing circuit 200, a signal isolation circuit 300 and a secondary driver circuit 400, wherein the isolation power supply circuit 100 and the signal isolation circuit 300 are electrically connected to the primary signal processing circuit 200 and the secondary driver circuit 400 respectively, and the secondary driver circuit 400 is used to be electrically connected to an external power switch tube 500.

[0019] Specifically, the secondary side driving circuit 400 includes an output control chip 410, a desaturation detection circuit 420, a Maitreya clamp circuit 430, and an overload protection circuit 440. The desaturation detection circuit 420, the Maitreya clamp circuit 430, and the overload protection circuit 440 all include a comparison circuit, and each comparison circuit is electrically connected to the output control chip 410 and the power switch tube 500, respectively. The isolated power supply circuit 100 includes a feedback control circuit 110 and an undervoltage protection circuit 120. The feedback control circuit 110 is used to be electrically connected to an external feedback regulation circuit 600. The undervoltage protection circuit 120 is electrically connected to the secondary side driving circuit 400 and is used to be electrically connected to an external undervoltage protection regulation circuit 700.

[0020] In this embodiment, in order to solve the problems that the isolation driving chip and the isolation power supply circuit are separated in the related art, resulting in the complicated design of the driving circuit of the power switch tube, the long wiring and the easy introduction of interference, etc., this embodiment packages the driving isolation power supply circuit and the isolation driving chip itself as one, thereby reducing the difficulty of the isolation driving circuit design, while improving the driving anti-interference ability and thus improving the reliability of the driving circuit. It should be noted that in the case where IGBT and MOSFET have isolation driving requirements, the related technology can also directly isolate and amplify the primary side driving signal through transformer driving (magnetic isolation), thereby eliminating the additional driving side isolation power supply. However, the transformer driving method requires the design of a driving protection circuit on the driving side. At the same time, due to the requirement of symmetrical wave generation of the transformer driving, this method can only be used to drive a circuit topology with a fixed 50% duty cycle, and its applicability is relatively low.

[0021] In order to improve the adaptability of the isolation driver chip, the isolation power supply circuit integrated inside the isolation driver chip is provided with an external adjustable output voltage function to match the different driving voltage requirements of different IGBTs and MOSFETs; when applied, the power supply voltage of the driving side (secondary driving circuit) of the isolation driver chip can be quickly adjusted through an external feedback adjustment circuit without adjusting the driving primary power supply or changing the isolation transformer design. In addition, in view of the limitation that the undervoltage protection point of the current isolation driver chip is fixed, in order to improve the adaptability and driving reliability of the IGBT and MOSFET driving circuits, the isolation driver chip in this embodiment is also provided with an external adjustable undervoltage protection point of the driving side in the isolation power supply circuit. By adjusting the external undervoltage protection adjustment circuit, different driving undervoltage protection points can be set to meet the driving requirements of different power switch tubes.

[0022] In addition, in order to improve driving reliability and reduce external driving protection circuits, this embodiment also integrates a desaturation detection circuit, a Maitreya clamping circuit, and an overload protection circuit in the secondary side driving circuit of the isolation driving chip; by detecting the parameter information of the external power switch tube and feeding it back to the output control chip, and then transmitting it to the primary side signal processing circuit by the output control chip, the internal parameters are adjusted to ensure the safety of the external power switch tube. Since the output control chip and the primary side signal processing circuit are isolated by the signal isolation circuit, the protection signal can be directly transmitted through the built-in isolation channel, with high reliability, and can save additional signal isolation transmission circuits, effectively reducing the complexity of the circuit structure.

[0023] like Figure 2 The circuit diagram of an isolation driver chip provided in this embodiment is shown in FIG. Figure 2 The desaturation detection circuit 420 further includes a current source Im, a second switch tube M3 and a second non-inverting amplifier A3. The comparison circuit of the desaturation detection circuit 420 includes a third comparator U3.

[0024] Specifically, the first end of the third comparator U3 is electrically connected to the output control chip 410, the second end of the third comparator U3 is electrically connected to the drain of the power switch tube 500, the third end of the third comparator U3 is used to be electrically connected to the external second reference signal generator, the second in-phase amplifier A3 is electrically connected to the output control chip 410 (Output Logic) and the first end of the second switch tube M3, the second end of the second switch tube M3 is electrically connected to the second end of the third comparator U3, the third end of the second switch tube M3 is grounded, and the current source Im is electrically connected to the second end of the third comparator U3 and the power supply end of the secondary side driving circuit 400. Among them, the first end of the undervoltage protection circuit 120 (UVL0) is electrically connected to the external undervoltage protection regulation circuit 700, and the second end of the undervoltage protection circuit UVL0 is electrically connected to the power supply end of the secondary side driving circuit 400.

[0025] The desaturation detection circuit in this embodiment provides a small current to the outside through the internal current source Im, and when the driving signal output by the output control chip is at a high level, the desaturation detection circuit can detect the voltage of the IGBT or MOSFET drain through the external DESAT pin, for example Figure 3 As shown in the structural diagram of the actual application of the isolation driver chip, the DESAT pin of the isolation driver chip is connected to the drain of the IGBT or MOSFET through a resistor and a diode, and the detected voltage is compared with the internally set protection voltage Vref. The output control chip of the secondary side drive circuit determines whether the main power tube IGBT or MOSFET is in a desaturation or overcurrent state based on the comparison signal. If so, corresponding protection measures are taken in time.

[0026] For further information, see Figure 2 and Figure 3 The Maitreya clamp circuit 430 also includes a third switch tube M6 and a third common-mode amplifier A4. The comparison circuit of the Maitreya clamp circuit 430 includes a fourth comparator U4.

[0027] Specifically, a first end of the fourth comparator U4 is electrically connected to the output control chip Output Logic, a second end of the fourth comparator U4 is electrically connected to the gate of the power switch tube, a third end of the fourth comparator U4 is electrically connected to the third reference signal generator, a third in-phase amplifier A4 is electrically connected to the output control chip Output Logic and a first end of the third switch tube M6 respectively, a second end of the third switch tube M6 is electrically connected to the second end of the fourth comparator U4, and a third end of the third switch tube M6 is grounded.

[0028] The Maitreya clamp circuit in this embodiment is connected to the gate of the driven IGBT or MOSFET through an external CLAMP pin. When the drive output is turned off, the voltage detected on the pin is compared with the internal clamp protection voltage Vclamp. The output control chip of the secondary side drive circuit determines whether to perform clamp protection based on the comparison signal, and controls the opening and closing of the clamp protection switch tube M6 accordingly.

[0029] Further, see Figure 2 and Figure 3 The overload protection circuit 440 also includes a power supply chip 5V_out, and the comparison circuit of the overload protection circuit 440 includes a fifth comparator U5; the power supply chip 5V_out is used to be electrically connected to an external temperature sampling circuit or a current sampling circuit, a first end of the fifth comparator U5 is electrically connected to the output control chip Output Logic, a second end of the fifth comparator U5 is used to be electrically connected to the temperature sampling circuit or the current sampling circuit, and a third end of the fifth comparator U5 is electrically connected to the fourth reference signal generator.

[0030] Specifically, the overload protection circuit in this embodiment provides a 5V voltage to the outside, and then connects an external voltage divider circuit such as an NTC thermistor, a shunt, etc. for temperature sampling when used, and then connects the voltage divider value back to the Vp pin of the chip, and compares the sampled voltage divider value with the built-in reference level Vref1 to achieve temperature protection and overcurrent protection.

[0031] For further information, see Figure 2 The isolation driving chip also includes a fourth common-mode amplifier A5, a fifth common-mode amplifier A6, a fourth switch tube M4 and a fifth switch tube M5.

[0032] Specifically, the fourth common-mode amplifier A5 is electrically connected to the output control chip Output Logic and the first end of the fourth switch tube M4, respectively; the second end of the fourth switch tube M4 is electrically connected to the external power supply VDD; the third end of the fourth switch tube M4 is electrically connected to the first end of the fifth switch tube M5; and the common connection end of the fourth switch tube M4 and the fifth switch tube M5 is electrically connected to the gate of the power switch tube 500; the fifth common-mode amplifier A6 is electrically connected to the output control chip Output Logic and the second end of the fifth switch tube M5, respectively; and the third end of the fifth switch tube M5 is grounded.

[0033] The output terminal OUT of the secondary output circuit of this embodiment is used to drive an external power switch tube. A common-mode amplifier and a switch tube are arranged on the drive signal output branch to achieve amplification and regulation of the drive signal.

[0034] like Figure 4The circuit diagram of the second isolation driver chip provided in this embodiment is shown in FIG. Figure 3 and Figure 4 The isolated power supply circuit 100 further includes a power control chip Control Logic, a soft start circuit Soft Start, an oscillator Oscillator, a first comparator U1 and a switch control circuit.

[0035] Specifically, the soft start circuit Soft Start and the oscillator Oscillator are electrically connected to the power control chip ControlLogic, the first end of the first comparator U1 is electrically connected to the external enable control signal generator, the second end of the first comparator U1 is electrically connected to the external first reference signal generator, the power end of the power control chip ControlLogic is electrically connected to the external power supply Vin, the feedback control circuit 110 is electrically connected to the power control chip ControlLogic, one end of the switch control circuit is electrically connected to the external transformer circuit, and the other end of the switch control circuit is electrically connected to the power control chip ControlLogic.

[0036] More specifically, the switch control circuit includes a first common-mode amplifier A1, a first switch tube M1, a second comparator U2 and a resistor Rs; the first common-mode amplifier A1 is electrically connected to the power control chip Control Logic and the first end of the first switch tube M1 respectively, the second end of the first switch tube M1 is used to be electrically connected to an external transformer circuit, the third end of the first switch tube M1 is electrically connected to one end of the resistor Rs, the other end of the resistor Rs is grounded, the first end and the second end of the second comparator U2 are electrically connected to the two ends of the resistor Rs respectively, and the third end of the second comparator U2 is electrically connected to the power control chip Control Logic.

[0037] In this embodiment, in order to meet the driving voltage requirements of different IGBTs and MOSFETs, a closed-loop feedback control circuit is integrated in the isolated power supply circuit in this embodiment. The feedback control circuit can be connected to an external feedback adjustment circuit through an external feedback adjustment pin Fb. The feedback adjustment circuit can obtain different isolated driving voltages by setting a resistance value or setting different voltage signals. The SW terminal on the chip corresponds to the switch control circuit. The SW port is connected to an external circuit or power supply to receive control signals from the outside, and these control signals are used to adjust the working state inside the chip. In addition, the En terminal in this embodiment is an enable terminal. The soft start circuit can reduce the impact and fluctuation at startup by gradually increasing the working state of the circuit (such as gradually increasing the power supply voltage or slowly starting certain circuit elements) when the power is just turned on, which helps to protect the stability of the circuit and extend its service life. The primary signal processing circuit in this embodiment transmits the feedback signal transmitted by the secondary drive circuit to an external device through an external / FAULT terminal, such as transmitting it to a digital signal processor DSP for processing, and receives the input signal of the external control circuit through the external IN+ and IN- terminals.

[0038] The isolated driver chip provided by the embodiment of the utility model designs and packages the driving isolation power supply and the driver chip itself together, and then adds a driving protection circuit commonly used in the actual work of IGBT and MOSFET to the secondary side driving circuit, thereby reducing the difficulty of designing the application driving circuit, while improving the driving anti-interference ability and thus improving the reliability of the driving circuit; at the same time, the isolated power supply circuit can conveniently adjust the driving voltage and the corresponding undervoltage protection point on the driving side through external pins, which greatly improves the adaptability and reliability of different IGBT and MOSFET drives.

[0039] The embodiment of the utility model further provides a switching power supply, which includes the above-mentioned isolation driving chip.

[0040] It should be noted that the various embodiments in the present invention are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referenced to each other.

[0041] It should also be noted that, in the present invention, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0042] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined in the present invention may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown in the present invention, but will conform to the widest range consistent with the principles and novel features disclosed in the present invention.

Claims

1. An isolation driver chip, characterized in that: include: An isolated power supply circuit, a primary signal processing circuit, a signal isolation circuit and a secondary drive circuit, wherein the isolated power supply circuit and the signal isolation circuit are electrically connected to the primary signal processing circuit and the secondary drive circuit respectively, and the secondary drive circuit is used to be electrically connected to an external power switch tube; The secondary side driving circuit includes an output control chip, a desaturation detection circuit, a Maitreya clamp circuit, and an overload protection circuit. The desaturation detection circuit, the Maitreya clamp circuit, and the overload protection circuit all include a comparison circuit. Each of the comparison circuits is electrically connected to the output control chip and the power switch tube, respectively. The isolated power supply circuit includes a feedback control circuit and an undervoltage protection circuit. The feedback control circuit is used to be electrically connected to an external feedback regulation circuit. The undervoltage protection circuit is electrically connected to the secondary side driving circuit and is used to be electrically connected to an external undervoltage protection regulation circuit.

2. The isolation driver chip according to claim 1, characterized in that: The isolated power supply circuit also includes a power supply control chip, a first comparator and a switch control circuit; The first end of the first comparator is used to be electrically connected to an external enable control signal generator, the second end of the first comparator is used to be electrically connected to a first reference signal generator, the power supply end of the power control chip is electrically connected to an external power supply, the feedback control circuit is electrically connected to the power control chip, one end of the switch control circuit is used to be electrically connected to an external transformer circuit, and the other end of the switch control circuit is electrically connected to the power control chip.

3. The isolation driver chip according to claim 2, characterized in that: The isolated power supply circuit also includes a soft start circuit and an oscillator. The soft start circuit and the oscillator are both electrically connected to the power control chip.

4. The isolation driver chip according to claim 2, characterized in that: The switch control circuit includes a first common-mode amplifier, a first switch tube, a second comparator and a resistor; The first common-mode amplifier is electrically connected to the power control chip and the first end of the first switch tube respectively, the second end of the first switch tube is used to be electrically connected to an external transformer circuit, the third end of the first switch tube is electrically connected to one end of the resistor, and the other end of the resistor is grounded, the first end and the second end of the second comparator are electrically connected to the two ends of the resistor respectively, and the third end of the second comparator is electrically connected to the power control chip.

5. The isolation driver chip according to claim 1, characterized in that: The first end of the undervoltage protection circuit is electrically connected to the external undervoltage protection regulation circuit, and the second end of the undervoltage protection circuit is electrically connected to the power supply end of the secondary side driving circuit.

6. The isolation driver chip according to claim 1, characterized in that: The desaturation detection circuit further includes a current source, a second switch tube and a second in-phase amplifier, and the comparison circuit of the desaturation detection circuit includes a third comparator; The first end of the third comparator is electrically connected to the output control chip, the second end of the third comparator is electrically connected to the drain of the power switch tube, the third end of the third comparator is electrically connected to the second reference signal generator, the second in-phase amplifier is electrically connected to the output control chip and the first end of the second switch tube respectively, the second end of the second switch tube is electrically connected to the second end of the third comparator, the third end of the second switch tube is grounded, and the current source is electrically connected to the second end of the third comparator and the power supply end of the secondary drive circuit respectively.

7. The isolation driver chip according to claim 1, characterized in that: The Maitreya clamp circuit further includes a third switch tube and a third in-phase amplifier, and the comparison circuit of the Maitreya clamp circuit includes a fourth comparator; The first end of the fourth comparator is electrically connected to the output control chip, the second end of the fourth comparator is electrically connected to the gate of the power switch tube, the third end of the fourth comparator is electrically connected to the third reference signal generator, the third in-phase amplifier is electrically connected to the output control chip and the first end of the third switch tube respectively, the second end of the third switch tube is electrically connected to the second end of the fourth comparator, and the third end of the third switch tube is grounded.

8. The isolation driver chip according to claim 1, characterized in that: The overload protection circuit also includes a power supply chip, and the comparison circuit of the overload protection circuit includes a fifth comparator; the power supply chip is used to be electrically connected to an external temperature sampling circuit or a current sampling circuit, the first end of the fifth comparator is electrically connected to the output control chip, the second end of the fifth comparator is used to be electrically connected to the temperature sampling circuit or the current sampling circuit, and the third end of the fifth comparator is electrically connected to a fourth reference signal generator.

9. The isolation driver chip according to any one of claims 1 to 8, characterized in that: It also includes a fourth common-phase amplifier, a fifth common-phase amplifier, a fourth switch tube and a fifth switch tube; The fourth common-mode amplifier is electrically connected to the output control chip and the first end of the fourth switch tube, respectively; the second end of the fourth switch tube is electrically connected to an external power supply; the third end of the fourth switch tube is electrically connected to the first end of the fifth switch tube, and the common connection end of the fourth switch tube and the fifth switch tube is electrically connected to the gate of the power switch tube; the fifth common-mode amplifier is electrically connected to the second end of the output control chip and the fifth switch tube, respectively; and the third end of the fifth switch tube is grounded.

10. A switching power supply, characterized in that: It comprises the isolation driver chip as claimed in any one of claims 1 to 9.

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