Driving circuit and switching power supply

Abstract

The utility model discloses a driving circuit and a switching power supply. The driving circuit comprises an interlocking circuit, an upper bridge arm switching tube isolation driving circuit and a lower bridge arm switching tube isolation driving circuit. When the driving circuit works abnormally, the interlocking circuit pulls up the level of the negative input end of the upper bridge arm switching tube isolation driving circuit to a high level through the first reference signal, so that the positive output end and the negative output end of the upper bridge arm switching tube isolation driving circuit are both high levels, and an upper bridge arm switching tube cannot be driven; and the interlock circuit pulls up the level of the negative input end of the lower bridge arm switch tube isolation driving circuit to a high level through the second reference signal, so that the positive output end and the negative output end of the lower bridge arm switch tube isolation driving circuit are both high levels, and a lower bridge arm switch tube cannot be driven. According to the utility model, the protection capability of the product can be greatly improved.

Description

Technical Field

[0001] The utility model relates to the field of switch converters, in particular to a drive circuit and a switch power supply. Background Art

[0002] As the application fields of products in the power supply industry are becoming wider and wider, the requirements for the power level and voltage level of products are becoming higher and higher. Many products contain bridge structures. When it comes to bridge structures, there will be common driving problems. How to simply and effectively solve the common problems of bridge arms has become a problem that high-power bridge products must face. Factors such as low cost, simplicity, effectiveness, and reliability determine the economy and reliability of product design, which will form strong competitiveness in the market.

[0003] Traditional products often do not have a driver interlocking function when using software-driven control, so there are common hidden dangers in PWM modulation and it is impossible to ensure that the program always runs normally. The use of isolation transformer drive control can achieve natural interlocking because its output is an AC square wave, positive voltage conduction and negative voltage shutdown. However, the drive transformer is prone to wave loss when the duty cycle of the drive signal is very small, and the isolation drive transformer needs to be demagnetized in time. Therefore, transformer interlocking is only suitable for application scenarios where the interlocking switch tube drive duty cycle is the same and the duty cycle is relatively large. The application range is extremely narrow and only applies to a small number of specific circuits, and the cost is relatively high. Utility Model Content

[0004] In view of this, the purpose of the utility model is to propose a drive circuit and a switching power supply to realize a bridge-type isolation drive interlocking function for products with isolation drive requirements, so that the product can achieve fast and accurate drive interlocking protection at an extremely low cost.

[0005] As a first aspect of the present invention, the technical solution of the embodiment of the driving circuit provided is as follows:

[0006] A driving circuit for driving an upper bridge arm switch tube and a lower bridge arm switch tube, wherein the driving circuit comprises: an interlocking circuit, an upper bridge arm switch tube isolation driving circuit and a lower bridge arm switch tube isolation driving circuit;

[0007] The first drive signal input terminal of the interlock circuit is used to input the first drive signal, the second drive signal input terminal is used to input the second drive signal, the first reference signal input terminal is used to input the first reference signal, the second reference signal input terminal is used to input the second reference signal, the first positive output terminal is connected to the positive input terminal of the upper bridge arm switch tube isolation drive circuit, the first negative output terminal is connected to the negative input terminal of the upper bridge arm switch tube isolation drive circuit, the second positive output terminal is connected to the positive input terminal of the lower bridge arm switch tube isolation drive circuit, and the second negative output terminal is connected to the negative input terminal of the lower bridge arm switch tube isolation drive circuit. The positive output terminal and the negative output terminal of the upper bridge arm switch tube isolation drive circuit are used to output a drive signal for the upper bridge arm switch tube, and the positive output terminal and the negative output terminal of the lower bridge arm switch tube isolation drive circuit are used to provide a drive signal for the lower bridge arm switch tube;

[0008] When the driving circuit works abnormally: the interlock circuit will pull up the level of the negative input terminal of the upper bridge arm switch tube isolation driving circuit to a high level through the first reference signal, so that the positive output terminal and the negative output terminal of the upper bridge arm switch tube isolation driving circuit are both high levels, and the upper bridge arm switch tube cannot be driven; and the interlock circuit will pull up the level of the negative input terminal of the lower bridge arm switch tube isolation driving circuit to a high level through the second reference signal, so that the positive output terminal and the negative output terminal of the lower bridge arm switch tube isolation driving circuit are both high levels, and the lower bridge arm switch tube cannot be driven.

[0009] Preferably, the first drive signal input terminal of the interlock circuit is connected to its first positive output terminal, and the second drive signal input terminal is connected to its second positive output terminal; the interlock circuit comprises: a MOS tube Q1 and a MOS tube Q2; the gate of the MOS tube Q1 is connected to the second drive signal input terminal of the interlock circuit, the drain of the MOS tube Q1 is connected to the first reference signal input terminal of the interlock circuit, and the source of the MOS tube Q1 is connected to the first negative output terminal of the interlock circuit; the gate of the MOS tube Q2 is connected to the first drive signal input terminal of the interlock circuit, the drain of the MOS tube Q2 is connected to the second reference signal input terminal of the interlock circuit, and the source of the MOS tube Q2 is connected to the second negative output terminal of the interlock circuit.

[0010] Furthermore, a resistor R2 is connected between the first drive signal input terminal of the interlock circuit and its first positive output terminal, a resistor R7 is connected between the second drive signal input terminal of the interlock circuit and its second positive output terminal, a resistor R5 is connected between the gate of the MOS tube Q1 and the second drive signal input terminal of the interlock circuit, a resistor R3 is connected between the source of the MOS tube Q1 and the first negative output terminal of the interlock circuit, a resistor R9 is connected between the gate of the MOS tube Q2 and the first drive signal input terminal of the interlock circuit, and a resistor R8 is connected between the source of the MOS tube Q2 and the second negative output terminal of the interlock circuit.

[0011] Preferably, the upper bridge arm switch tube isolation drive circuit includes an isolation drive chip U1, the positive drive signal input end of the isolation drive chip U1 is the positive input end of the upper bridge arm switch tube isolation drive circuit, the negative drive signal input end is the negative input end of the upper bridge arm switch tube isolation drive circuit, the positive drive signal output end is the positive output end of the upper bridge arm switch tube isolation drive circuit, and the negative drive signal output end is the negative output end of the upper bridge arm switch tube isolation drive circuit.

[0012] Furthermore, the upper bridge arm switch tube isolation drive circuit also includes: a resistor R1, a resistor R4 and a Zener diode D1; the resistor R1 is connected to the positive drive signal input terminal and the GND ground signal terminal of the isolation drive chip U1, the resistor R4 is connected to the negative drive signal input terminal and the GND ground signal terminal of the isolation drive chip U1, and the anode of the Zener diode D1 is connected to the VSS power supply signal terminal of the isolation drive chip U1, and the cathode is connected to the negative drive signal output terminal of the isolation drive chip U1.

[0013] Preferably, the lower bridge arm switch tube isolation drive circuit includes an isolation drive chip U2, the positive drive signal input end of the isolation drive chip U2 is the positive input end of the lower bridge arm switch tube isolation drive circuit, the negative drive signal input end is the negative input end of the lower bridge arm switch tube isolation drive circuit, the positive drive signal output end is the positive output end of the lower bridge arm switch tube isolation drive circuit, and the negative drive signal output end is the negative output end of the lower bridge arm switch tube isolation drive circuit.

[0014] Furthermore, the lower bridge arm switch tube isolation drive circuit also includes: a resistor R6, a resistor R10 and a voltage regulator diode D2; the resistor R6 is connected to the positive drive signal input terminal and the GND ground signal terminal of the isolation drive chip U2, the resistor R10 is connected to the negative drive signal input terminal and the GND ground signal terminal of the isolation drive chip U2, and the anode of the voltage regulator diode D2 is connected to the VSS power supply signal terminal of the isolation drive chip U2, and the cathode is connected to the negative drive signal output terminal of the isolation drive chip U2.

[0015] Preferably, the first drive signal input terminal of the interlock circuit is connected to its first positive output terminal, and the second drive signal input terminal is connected to its second positive output terminal; the interlock circuit comprises: a MOS tube Q1 and a MOS tube Q2; the gate of the MOS tube Q1 is connected to the second drive signal input terminal of the interlock circuit, the drain of the MOS tube Q1 is connected to the first reference signal input terminal of the interlock circuit, and the source of the MOS tube Q1 is connected to the first negative output terminal of the interlock circuit; the gate of the MOS tube Q2 is connected to the first drive signal input terminal of the interlock circuit, the drain of the MOS tube Q2 is connected to the second reference signal input terminal of the interlock circuit, and the source of the MOS tube Q2 is connected to the second negative output terminal of the interlock circuit;

[0016] A resistor R2 is connected between the first drive signal input terminal of the interlock circuit and its first positive output terminal, a resistor R7 is connected between the second drive signal input terminal of the interlock circuit and its second positive output terminal, a resistor R5 is connected between the gate of the MOS tube Q1 and the second drive signal input terminal of the interlock circuit, a resistor R3 is connected between the source of the MOS tube Q1 and the first negative output terminal of the interlock circuit, a resistor R9 is connected between the gate of the MOS tube Q2 and the first drive signal input terminal of the interlock circuit, and a resistor R8 is connected between the source of the MOS tube Q2 and the second negative output terminal of the interlock circuit;

[0017] The upper bridge arm switch tube isolation driving circuit comprises an isolation driving chip U1, wherein the positive driving signal input terminal of the isolation driving chip U1 is the positive input terminal of the upper bridge arm switch tube isolation driving circuit, the negative driving signal input terminal is the negative input terminal of the upper bridge arm switch tube isolation driving circuit, the positive driving signal output terminal is the positive output terminal of the upper bridge arm switch tube isolation driving circuit, and the negative driving signal output terminal is the negative output terminal of the upper bridge arm switch tube isolation driving circuit;

[0018] The upper bridge arm switch tube isolation drive circuit also includes: a resistor R1, a resistor R4 and a voltage regulator diode D1; the resistor R1 is connected to the positive drive signal input terminal and the GND ground signal terminal of the isolation drive chip U1, the resistor R4 is connected to the negative drive signal input terminal and the GND ground signal terminal of the isolation drive chip U1, and the anode of the voltage regulator diode D1 is connected to the VSS power supply signal terminal of the isolation drive chip U1, and the cathode is connected to the negative drive signal output terminal of the isolation drive chip U1;

[0019] The lower bridge arm switch tube isolation drive circuit comprises an isolation drive chip U2, wherein the positive drive signal input terminal of the isolation drive chip U2 is the positive input terminal of the lower bridge arm switch tube isolation drive circuit, the negative drive signal input terminal is the negative input terminal of the lower bridge arm switch tube isolation drive circuit, the positive drive signal output terminal is the positive output terminal of the lower bridge arm switch tube isolation drive circuit, and the negative drive signal output terminal is the negative output terminal of the lower bridge arm switch tube isolation drive circuit;

[0020] The lower bridge arm switch tube isolation drive circuit also includes: a resistor R6, a resistor R10 and a voltage regulator diode D2; the resistor R6 is connected to the positive drive signal input terminal and the GND ground signal terminal of the isolation drive chip U2, the resistor R10 is connected to the negative drive signal input terminal and the GND ground signal terminal of the isolation drive chip U2, and the anode of the voltage regulator diode D2 is connected to the VSS power supply signal terminal of the isolation drive chip U2, and the cathode is connected to the negative drive signal output terminal of the isolation drive chip U2.

[0021] Preferably, the isolation driver chip U1 and the isolation driver chip U2 are UCC5350, 1ED3125 or NCD57080.

[0022] As a second aspect of the present invention, the technical solution of the embodiment of the switching power supply provided is as follows:

[0023] A switching power supply, comprising an upper bridge arm switch tube and a lower bridge arm switch tube, wherein the upper bridge arm switch tube and the lower bridge arm switch tube are driven by the driving circuit described in any one of the first aspects above.

[0024] Compared with the prior art, the utility model has the following beneficial effects:

[0025] (1) The interlocking circuit in the driving circuit of the embodiment of the utility model cross-connects the two driving signals and pulls up the level, so that when the driving circuit works abnormally, the interlocking circuit will pull up the level of the negative input end of the corresponding bridge arm switch tube isolation driving circuit to a high level through the corresponding reference signal, so that the positive output end and the negative output end of the corresponding bridge arm switch tube isolation driving circuit are both high levels, so that the upper bridge arm switch tube isolation driving circuit and the lower bridge arm switch tube isolation driving circuit generate two interlocking driving signals that can independently drive the switch tubes. It is independent of the circuit topology type, switch tube type and duty cycle size of the application products such as switching power supplies, and is suitable for all products with isolation drive requirements, and has a wide range of applicability;

[0026] (2) The driving circuit of the embodiment of the utility model realizes interlock protection through hardware, so the protection speed and protection accuracy are greatly improved. At the same time, since no additional single-chip microcomputer is required for control, it does not occupy single-chip microcomputer resources, and the control logic is simple and independent, thereby greatly improving the protection capability of application products such as switching power supplies. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a specific circuit principle diagram of the driving circuit of the first embodiment of the utility model. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned purposes, features and advantages of the utility model more obvious and easy to understand, the specific implementation methods of the utility model are described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this application.

[0029] It should be noted that the terms "including" and "having" and any variations thereof described in the specification and claims of the present application are intended to cover non-exclusive inclusions. For example, the inclusion of a series of components, unit circuits or control timings is not necessarily limited to those components, unit circuits or control timings clearly listed, but may include components, unit circuits or control timings that are not clearly listed or inherent to these circuits.

[0030] In addition, the embodiments and features of the embodiments in this application may be combined with each other if there is no conflict.

[0031] It should be understood that, in the specification and the claims, when an element is described as being “connected” to another element, the element may be “directly connected” to the other element, or be “connected” to the other element through a third element; when a step is described as being continued to another step, the step may be directly continued to the other step, or be continued to the other step through a third step.

[0032] First embodiment

[0033] This embodiment provides a driving circuit for driving an upper bridge arm switch tube and a lower bridge arm switch tube. Figure 1 A specific circuit schematic diagram of the driving circuit of the first embodiment of the utility model is shown in FIG. Figure 1 , wherein the driving circuit includes: an interlocking circuit, an upper bridge arm switch tube isolation driving circuit and a lower bridge arm switch tube isolation driving circuit;

[0034] The first drive signal input terminal of the interlock circuit is used to input the first drive signal Drv_A, the second drive signal input terminal is used to input the second drive signal Drv_B, the first reference signal input terminal is used to input the first reference signal VREF, and the second reference signal input terminal is used to input the second reference signal VREF ( Figure 1 The first reference signal and the second reference signal are both VREF), the first positive output end is connected to the positive input end IN+ of the upper bridge arm switch tube isolation driving circuit, the first negative output end is connected to the negative input end IN- of the upper bridge arm switch tube isolation driving circuit, the second positive output end is connected to the positive input end IN+ of the lower bridge arm switch tube isolation driving circuit, and the second negative output end is connected to the negative input end IN- of the lower bridge arm switch tube isolation driving circuit, the positive output end OUT+ and the negative output end OUT- of the upper bridge arm switch tube isolation driving circuit are used to output a driving signal for the upper bridge arm switch tube, and the positive output end OUT+ and the negative output end OUT- of the lower bridge arm switch tube isolation driving circuit are used to output a driving signal for the lower bridge arm switch tube;

[0035] When the driving circuit works abnormally: the interlock circuit will pull up the level of the negative input terminal of the upper arm switch tube isolation driving circuit to a high level through the first reference signal, so that the positive output terminal and the negative output terminal of the upper arm switch tube isolation driving circuit are both high levels, and the upper arm switch tube cannot be driven; and the interlock circuit will pull up the level of the negative input terminal of the lower arm switch tube isolation driving circuit to a high level through the second reference signal, so that the positive output terminal and the negative output terminal of the lower arm switch tube isolation driving circuit are both high levels, and the lower arm switch tube cannot be driven.

[0036] Among them, the drive interlock circuit cross-connects the two drive signals and performs interlocking through the hardware circuit to achieve the two-way drive interlocking protection function, and sends the interlocked drive signals to the upper bridge arm switch tube isolation drive circuit and the lower bridge arm switch tube isolation drive circuit respectively.

[0037] Among them, the upper bridge arm switch tube isolation drive circuit amplifies and outputs the corresponding interlock drive signal generated by the interlock circuit, generates an interlock drive signal that can independently drive the upper bridge arm switch tube, and controls the upper bridge arm switch tube.

[0038] Among them, the lower bridge arm switch tube isolation drive circuit amplifies and outputs the corresponding interlock drive signal generated by the interlock circuit, generates an interlock drive signal that can independently drive the lower bridge arm switch tube, and controls the lower bridge arm switch tube.

[0039] In a specific implementation, the upper bridge arm switch tube and the lower bridge arm switch tube can be MOS tubes, thyristors, IGBTs, etc. The connection relationship between the upper bridge arm switch tube and the lower bridge arm switch tube can be known to technicians in this field. For example, when the upper bridge arm switch tube and the lower bridge arm switch tube are MOS tubes, the positive output terminal OUT+ of the upper bridge arm switch tube isolation drive circuit is connected to the gate of the MOS tube, and the negative output terminal OUT- is connected to the source of the MOS tube, thereby outputting a drive signal for the upper bridge arm switch tube.

[0040] The interlocking circuit in the driving circuit of this embodiment cross-connects the two driving signals and pulls up the levels, so that when the driving circuit works abnormally, the interlocking circuit will pull up the level of the negative input end of the corresponding bridge arm switch tube isolation driving circuit to a high level through the corresponding reference signal, so that the positive output end and the negative output end of the corresponding bridge arm switch tube isolation driving circuit are both high levels, thereby realizing that the upper bridge arm switch tube isolation driving circuit and the lower bridge arm switch tube isolation driving circuit generate two interlocking driving signals that can independently drive the switch tubes, which is independent of the circuit topology type, switch tube type and duty cycle of application products such as switching power supplies, and is suitable for all products with isolation drive requirements, and has a wide range of applicability.

[0041] In addition, the driving circuit of this embodiment implements interlocking protection through hardware, so the protection speed and protection accuracy are greatly improved. At the same time, since no additional microcontroller is required for control, it does not occupy microcontroller resources, and the control logic is simple and independent, thereby greatly improving the protection capabilities of application products such as switching power supplies.

[0042] Please continue to see Figure 1 , wherein the first drive signal input terminal of the interlock circuit is connected to its first positive output terminal, and the second drive signal input terminal is connected to its second positive output terminal; the interlock circuit comprises: a MOS tube Q1 and a MOS tube Q2; the gate of the MOS tube Q1 is connected to the second drive signal input terminal of the interlock circuit, the drain of the MOS tube Q1 is connected to the first reference signal input terminal of the interlock circuit, and the source of the MOS tube Q1 is connected to the first negative output terminal of the interlock circuit; the gate of the MOS tube Q2 is connected to the first drive signal input terminal of the interlock circuit, the drain of the MOS tube Q2 is connected to the second reference signal input terminal of the interlock circuit, and the source of the MOS tube Q2 is connected to the second negative output terminal of the interlock circuit.

[0043] Please continue to see Figure 1, wherein a resistor R2 is connected between the first drive signal input terminal and the first positive output terminal of the interlock circuit, which is used to limit the current of the drive signal to prevent it from generating a large current impact and damaging the isolation drive chip; a resistor R7 is connected between the second drive signal input terminal and the second positive output terminal of the interlock circuit, which is used to limit the current of the drive signal to prevent it from generating a large current impact and damaging the isolation drive chip; a resistor R5 is connected between the gate of the MOS tube Q1 and the second drive signal input terminal of the interlock circuit, which is used to limit the current of the drive signal to prevent it from generating a large current impact and damaging the MOS MOS tube Q1; a resistor R3 is connected between the source of the MOS tube Q1 and the first negative output terminal of the interlock circuit, which is used to limit the current of the drive signal to prevent it from generating a large current impact and damaging the isolation driver chip; a resistor R9 is connected between the gate of the MOS tube Q2 and the first drive signal input terminal of the interlock circuit, which is used to limit the current of the drive signal to prevent it from generating a large current impact and damaging the MOS tube Q2; a resistor R8 is connected between the source of the MOS tube Q2 and the second negative output terminal of the interlock circuit, which is used to limit the current of the drive signal to prevent it from generating a large current impact and damaging the isolation driver chip.

[0044] Please continue to see Figure 1 The upper-bridge-arm switch tube isolation driving circuit includes an isolation driving chip U1, wherein the positive driving signal input terminal of the isolation driving chip U1 is the positive input terminal of the upper-bridge-arm switch tube isolation driving circuit, the negative driving signal input terminal is the negative input terminal of the upper-bridge-arm switch tube isolation driving circuit, the positive driving signal output terminal is the positive output terminal of the upper-bridge-arm switch tube isolation driving circuit, and the negative driving signal output terminal is the negative output terminal of the upper-bridge-arm switch tube isolation driving circuit.

[0045] Please continue to see Figure 1 , wherein the upper bridge arm switch tube isolation drive circuit also includes: a resistor R1, a resistor R4 and a voltage regulator diode D1; the resistor R1 and the capacitor C3 are connected in parallel to the positive drive signal input terminal and the GND ground signal terminal of the isolation drive chip U1, and are used to connect the input terminal of the isolation drive chip U1 to the ground when the drive signal is turned off, so as to ensure that the drive signal is reliably turned off; the resistor R4 is connected to the negative drive signal input terminal and the GND ground signal terminal of the isolation drive chip U1, and is used to connect the input terminal of the isolation drive chip U1 to the ground when the drive signal is turned off, so as to ensure that the drive signal is reliably turned off; the anode of the voltage regulator diode D1 is connected to the VSS power supply signal terminal of the isolation drive chip U1, and the cathode is connected to the negative drive signal output terminal of the isolation drive chip U1, so as to provide a specific negative voltage in the negative voltage drive scenario, and reliable shutdown in the conventional drive scenario.

[0046] Please continue to see Figure 1The lower bridge arm switch tube isolation drive circuit includes an isolation drive chip U2, the positive drive signal input end of the isolation drive chip U2 is the positive input end of the lower bridge arm switch tube isolation drive circuit, the negative drive signal input end is the negative input end of the lower bridge arm switch tube isolation drive circuit, the positive drive signal output end is the positive output end of the lower bridge arm switch tube isolation drive circuit, and the negative drive signal output end is the negative output end of the lower bridge arm switch tube isolation drive circuit.

[0047] Please continue to see Figure 1 , wherein the lower bridge arm switch tube isolation drive circuit also includes: a resistor R6, a resistor R10, a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C8 and a voltage regulator diode D2; the resistor R6 and the capacitor C7 are connected in parallel to the positive drive signal input terminal and the GND ground signal terminal of the isolation drive chip U2, and are used to connect the input terminal of the isolation drive chip U2 to the ground when the drive signal is turned off, so as to ensure that the drive signal is reliably turned off; the resistor R10 is connected to the negative drive signal input terminal and the GND ground signal terminal of the isolation drive chip U2, and is used to connect the input terminal of the isolation drive chip U2 to the ground when the drive signal is turned off, so as to ensure that the drive signal is reliably turned off; the anode of the voltage regulator diode D2 is connected to the VSS power supply signal terminal of the isolation drive chip U2, and the cathode is connected to the negative drive signal output terminal of the isolation drive chip U2, so as to provide a specific negative voltage in the negative voltage drive scenario, and reliable shutdown in the conventional drive scenario.

[0048] Preferably, the isolation driver chip U1 and the isolation driver chip U2 are UCC5350 of TI, 1ED3125 of Infineon, and NCD57080 of ON. These chips are all compatible with the package, and the pin definitions are as follows:

[0049] (1) Pin 1, i.e. the power supply VDD pin: It is the positive terminal of the power supply before isolation and can be adapted according to the driving voltage;

[0050] (2) Pin 2, i.e. input signal VIN+: the positive terminal of the input drive signal before isolation;

[0051] (3) Pin 3, i.e. input signal VIN-: negative terminal of input drive signal before isolation;

[0052] (4) Pin 4, i.e. reference ground GND: It is the negative terminal of the power supply before isolation and shares the same ground with the drive signal;

[0053] (5) Pin 5, i.e. power supply VSS: It is the negative terminal of the isolated power supply and can realize different negative voltage drives;

[0054] (6) Pin 6, i.e. output signal OUT-: negative terminal of the isolated input drive signal;

[0055] (7) Pin 7, i.e. output signal OUT+: the positive terminal of the isolated input drive signal;

[0056] (8) Pin 8, i.e. power supply VCC: It is the positive terminal of the isolated power supply and can realize different positive voltage drives.

[0057] Figure 1 When the circuit is applied to products such as switching power supplies, the working principle is analyzed as follows:

[0058] When the product operates normally, the drive signal Drv_A is at a high level, and the drive signal Drv_B is at a low level. The drive signal state of the upper bridge arm switch tube is analyzed: the second pin of the isolation driver chip U1 is the high level of the Drv_A drive signal. Because the drive signal Drv_B is at a low level, the MOS tube Q1 is turned off, and the third pin of the isolation driver chip U1 is pulled down to the ground signal GND by the fourth resistor R4. At this time, the sixth pin of the isolation driver chip U1 outputs a low level, and the seventh pin of the isolation driver chip U1 outputs a high level, driving the upper bridge arm switch tube to turn on; similarly, when the product operates normally, the sixth pin of the isolation driver chip U2 of the lower bridge arm switch tube outputs a low level, and the seventh pin of the isolation driver chip U2 outputs a high level, driving the lower bridge arm switch tube to turn on.

[0059] When the product driving signal is abnormal, the driving signal Drv_A and the driving signal Drv_B are both high-level and common. By analyzing the driving signal state of the upper bridge arm switch tube, it can be known that at this time, the second pin of the isolation driving chip U1 is the high level of the Drv_A driving signal, and the driving signal Drv_B drives the MOS tube Q1 to turn on through the fifth resistor R5. The third pin of the isolation driving chip U1 is pulled up to a high level by the reference signal VREF. Therefore, the outputs of the sixth pin and the seventh pin of the isolation driving chip U1 are both high-level, and the upper bridge arm switch tube cannot be driven to turn on; similarly, the outputs of the isolation driving chip U2 of the lower bridge arm switch tube are also high-level, and the lower bridge arm switch tube cannot be driven to turn on, realizing the isolation driving interlocking function. Therefore, when the driving signal Drv_A and the driving signal Drv_B are both high-level, the driving signal cannot be transmitted to the upper bridge arm switch tube and the lower bridge arm switch tube, and the upper bridge arm switch tube and the lower bridge arm switch tube are always in the off state, thereby ensuring that when the driving signal is abnormal, the upper bridge arm switch tube and the lower bridge arm switch tube of the product will not be damaged due to commonality.

[0060] Second embodiment

[0061] This embodiment provides a switching power supply, which includes an upper bridge arm switch tube and a lower bridge arm switch tube, and the upper bridge arm switch tube and the lower bridge arm switch tube are driven by any driving circuit of the first embodiment.

[0062] In this embodiment, since the upper bridge arm switch tube and the lower bridge arm switch tube are driven by any driving circuit of the first embodiment, fast and accurate drive interlock protection can be achieved at a very low cost.

[0063] The above are only preferred embodiments of the present invention. If more equivalent variations or substitutions are added on this basis, they should also fall within the protection scope of the patent. It should be pointed out that the above preferred embodiments should not be regarded as limitations on the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention. The embodiments will not be repeated here. The protection scope of the present invention should be based on the scope defined by the claims.

Claims

1. A driving circuit for driving an upper bridge arm switch tube and a lower bridge arm switch tube, characterized in that: The driving circuit comprises: an interlocking circuit, an upper bridge arm switch tube isolation driving circuit and a lower bridge arm switch tube isolation driving circuit; The first drive signal input terminal of the interlock circuit is used to input the first drive signal, the second drive signal input terminal is used to input the second drive signal, the first reference signal input terminal is used to input the first reference signal, the second reference signal input terminal is used to input the second reference signal, the first positive output terminal is connected to the positive input terminal of the upper bridge arm switch tube isolation drive circuit, the first negative output terminal is connected to the negative input terminal of the upper bridge arm switch tube isolation drive circuit, the second positive output terminal is connected to the positive input terminal of the lower bridge arm switch tube isolation drive circuit, and the second negative output terminal is connected to the negative input terminal of the lower bridge arm switch tube isolation drive circuit. The positive output terminal and the negative output terminal of the upper bridge arm switch tube isolation drive circuit are used to output a drive signal for the upper bridge arm switch tube, and the positive output terminal and the negative output terminal of the lower bridge arm switch tube isolation drive circuit are used to provide a drive signal for the lower bridge arm switch tube; When the driving circuit works abnormally: the interlock circuit will pull up the level of the negative input terminal of the upper bridge arm switch tube isolation driving circuit to a high level through the first reference signal, so that the positive output terminal and the negative output terminal of the upper bridge arm switch tube isolation driving circuit are both high levels, and the upper bridge arm switch tube cannot be driven; and the interlock circuit will pull up the level of the negative input terminal of the lower bridge arm switch tube isolation driving circuit to a high level through the second reference signal, so that the positive output terminal and the negative output terminal of the lower bridge arm switch tube isolation driving circuit are both high levels, and the lower bridge arm switch tube cannot be driven.

2. The driving circuit according to claim 1, characterized in that: The first drive signal input terminal of the interlock circuit is connected to its first positive output terminal, and the second drive signal input terminal is connected to its second positive output terminal; the interlock circuit comprises: a MOS tube Q1 and a MOS tube Q2; the gate of the MOS tube Q1 is connected to the second drive signal input terminal of the interlock circuit, the drain of the MOS tube Q1 is connected to the first reference signal input terminal of the interlock circuit, and the source of the MOS tube Q1 is connected to the first negative output terminal of the interlock circuit; the gate of the MOS tube Q2 is connected to the first drive signal input terminal of the interlock circuit, the drain of the MOS tube Q2 is connected to the second reference signal input terminal of the interlock circuit, and the source of the MOS tube Q2 is connected to the second negative output terminal of the interlock circuit.

3. The driving circuit according to claim 2, characterized in that: A resistor R2 is connected between the first drive signal input terminal of the interlock circuit and its first positive output terminal, a resistor R7 is connected between the second drive signal input terminal of the interlock circuit and its second positive output terminal, a resistor R5 is connected between the gate of the MOS tube Q1 and the second drive signal input terminal of the interlock circuit, a resistor R3 is connected between the source of the MOS tube Q1 and the first negative output terminal of the interlock circuit, a resistor R9 is connected between the gate of the MOS tube Q2 and the first drive signal input terminal of the interlock circuit, and a resistor R8 is connected between the source of the MOS tube Q2 and the second negative output terminal of the interlock circuit.

4. The driving circuit according to claim 1, characterized in that: The upper bridge arm switch tube isolation drive circuit includes an isolation drive chip U1, the positive drive signal input end of the isolation drive chip U1 is the positive input end of the upper bridge arm switch tube isolation drive circuit, the negative drive signal input end is the negative input end of the upper bridge arm switch tube isolation drive circuit, the positive drive signal output end is the positive output end of the upper bridge arm switch tube isolation drive circuit, and the negative drive signal output end is the negative output end of the upper bridge arm switch tube isolation drive circuit.

5. The driving circuit according to claim 4, characterized in that: The upper bridge arm switch tube isolation drive circuit also includes: a resistor R1, a resistor R4 and a voltage regulator diode D1; the resistor R1 is connected to the positive drive signal input terminal and the GND ground signal terminal of the isolation drive chip U1, the resistor R4 is connected to the negative drive signal input terminal and the GND ground signal terminal of the isolation drive chip U1, and the anode of the voltage regulator diode D1 is connected to the VSS power supply signal terminal of the isolation drive chip U1, and the cathode is connected to the negative drive signal output terminal of the isolation drive chip U1.

6. The driving circuit according to claim 1, characterized in that: The lower bridge arm switch tube isolation drive circuit includes an isolation drive chip U2, the positive drive signal input end of the isolation drive chip U2 is the positive input end of the lower bridge arm switch tube isolation drive circuit, the negative drive signal input end is the negative input end of the lower bridge arm switch tube isolation drive circuit, the positive drive signal output end is the positive output end of the lower bridge arm switch tube isolation drive circuit, and the negative drive signal output end is the negative output end of the lower bridge arm switch tube isolation drive circuit.

7. The driving circuit according to claim 6, characterized in that: The lower bridge arm switch tube isolation drive circuit also includes: a resistor R6, a resistor R10 and a voltage regulator diode D2; the resistor R6 is connected to the positive drive signal input terminal and the GND ground signal terminal of the isolation drive chip U2, the resistor R10 is connected to the negative drive signal input terminal and the GND ground signal terminal of the isolation drive chip U2, and the anode of the voltage regulator diode D2 is connected to the VSS power supply signal terminal of the isolation drive chip U2, and the cathode is connected to the negative drive signal output terminal of the isolation drive chip U2.

8. The driving circuit according to claim 1, characterized in that: The first drive signal input terminal of the interlock circuit is connected to its first positive output terminal, and the second drive signal input terminal is connected to its second positive output terminal; the interlock circuit comprises: a MOS tube Q1 and a MOS tube Q2; the gate of the MOS tube Q1 is connected to the second drive signal input terminal of the interlock circuit, the drain of the MOS tube Q1 is connected to the first reference signal input terminal of the interlock circuit, and the source of the MOS tube Q1 is connected to the first negative output terminal of the interlock circuit; the gate of the MOS tube Q2 is connected to the first drive signal input terminal of the interlock circuit, the drain of the MOS tube Q2 is connected to the second reference signal input terminal of the interlock circuit, and the source of the MOS tube Q2 is connected to the second negative output terminal of the interlock circuit; A resistor R2 is connected between the first drive signal input terminal of the interlock circuit and its first positive output terminal, a resistor R7 is connected between the second drive signal input terminal of the interlock circuit and its second positive output terminal, a resistor R5 is connected between the gate of the MOS tube Q1 and the second drive signal input terminal of the interlock circuit, a resistor R3 is connected between the source of the MOS tube Q1 and the first negative output terminal of the interlock circuit, a resistor R9 is connected between the gate of the MOS tube Q2 and the first drive signal input terminal of the interlock circuit, and a resistor R8 is connected between the source of the MOS tube Q2 and the second negative output terminal of the interlock circuit; The upper bridge arm switch tube isolation driving circuit comprises an isolation driving chip U1, wherein the positive driving signal input terminal of the isolation driving chip U1 is the positive input terminal of the upper bridge arm switch tube isolation driving circuit, the negative driving signal input terminal is the negative input terminal of the upper bridge arm switch tube isolation driving circuit, the positive driving signal output terminal is the positive output terminal of the upper bridge arm switch tube isolation driving circuit, and the negative driving signal output terminal is the negative output terminal of the upper bridge arm switch tube isolation driving circuit; The upper bridge arm switch tube isolation drive circuit also includes: a resistor R1, a resistor R4 and a voltage regulator diode D1; the resistor R1 is connected to the positive drive signal input terminal and the GND ground signal terminal of the isolation drive chip U1, the resistor R4 is connected to the negative drive signal input terminal and the GND ground signal terminal of the isolation drive chip U1, and the anode of the voltage regulator diode D1 is connected to the VSS power supply signal terminal of the isolation drive chip U1, and the cathode is connected to the negative drive signal output terminal of the isolation drive chip U1; The lower bridge arm switch tube isolation drive circuit comprises an isolation drive chip U2, wherein the positive drive signal input terminal of the isolation drive chip U2 is the positive input terminal of the lower bridge arm switch tube isolation drive circuit, the negative drive signal input terminal is the negative input terminal of the lower bridge arm switch tube isolation drive circuit, the positive drive signal output terminal is the positive output terminal of the lower bridge arm switch tube isolation drive circuit, and the negative drive signal output terminal is the negative output terminal of the lower bridge arm switch tube isolation drive circuit; The lower bridge arm switch tube isolation drive circuit also includes: a resistor R6, a resistor R10 and a voltage regulator diode D2; the resistor R6 is connected to the positive drive signal input terminal and the GND ground signal terminal of the isolation drive chip U2, the resistor R10 is connected to the negative drive signal input terminal and the GND ground signal terminal of the isolation drive chip U2, and the anode of the voltage regulator diode D2 is connected to the VSS power supply signal terminal of the isolation drive chip U2, and the cathode is connected to the negative drive signal output terminal of the isolation drive chip U2.

9. The driving circuit according to claim 8, characterized in that: The isolation driver chip U1 and the isolation driver chip U2 are UCC5350, 1ED3125 or NCD57080.

10. A switching power supply, comprising an upper bridge arm switch tube and a lower bridge arm switch tube, characterized in that: The upper bridge arm switch tube and the lower bridge arm switch tube are driven by the driving circuit according to any one of claims 1 to 9.

Images