CN-121710145-B - Reverse polarity protection circuit, switch module and application circuit thereof

CN121710145BCN 121710145 BCN121710145 BCN 121710145BCN-121710145-B

Abstract

The present invention relates to the field of circuit design technologies, and in particular, to a reverse polarity protection circuit, a switch module, and an application circuit thereof. The reverse polarity protection circuit comprises a first NMOS tube MN1, a second NMOS tube MN2, a third NMOS tube MN3, a fourth NMOS tube MN4, a fifth NMOS tube MN5, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a first resistor R1, a second resistor R2, a third resistor R3, a fifth resistor R5, a first PMOS tube MP1 and a second PMOS tube MP2. The invention actively turns on the power tube when the reverse polarity event occurs to form a low-resistance passage so as to replace the body diode to be conducted, thereby greatly reducing the power consumption, and the gate-source and drain-source voltages of each MOS tube are in a safe range under all working states (normal on/off, inductive load and reverse polarity) of the circuit, thereby having no super-withstand voltage risk, being applicable to standard process and reducing the manufacturing cost and design complexity.

Inventors

ZHANG JIAZHEN
LI YE
HUANG HAODAN

Assignees

无锡硅动力微电子股份有限公司

Dates

Publication Date: 20260505
Application Date: 20260204

Claims (8)

1. The reverse polarity protection circuit is characterized by comprising a first NMOS tube MN1, a second NMOS tube MN2, a third NMOS tube MN3, a fourth NMOS tube MN4, a fifth NMOS tube MN5, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a first resistor R1, a second resistor R2, a third resistor R3, a fifth resistor R5, a first PMOS tube MP1 and a second PMOS tube MP2; The drain electrode of the first NMOS tube MN1 is connected with an internal power supply voltage VCC, the grid electrode is connected with an internal ground GND_INT, the source electrode is connected with the source electrode of a second NMOS tube MN2, the grid electrode of the second NMOS tube MN2 is connected with the internal ground GND_INT, the drain electrode is connected with one end of a second resistor R2 and the negative electrode of a fourth diode D4, the positive electrode of the fourth diode D4 is connected with the internal ground GND_INT, the other end of the second resistor R2 is connected with the grid electrode of the first PMOS tube MP1, the grid electrode of the second PMOS tube MP2 and one end of a first resistor R1, the source electrode of the first PMOS tube MP1, the source electrode of the second PMOS tube MP2 and the other end of the first resistor R1 are connected with input control signals, the drain electrode of the first PMOS tube MP1 is connected with the source electrode of a third NMOS tube MN3, one end of the third resistor R3 and the grid electrode of a fifth NMOS tube MN5, the drain electrode of the second PMOS transistor MP2 is connected to the positive electrode of the first diode D1, the negative electrode of the first diode D1 is connected to the source electrode of the fifth NMOS transistor MN5, the gate electrode of the third NMOS transistor MN3 is connected to the level signal, the drain electrode of the third NMOS transistor MN3 is connected to the positive electrode of the second diode D2, the negative electrode of the second diode D2 is connected to one end of the fifth resistor R5, the other end of the fifth resistor R5 is connected to the OUTPUT port OUTPUT, the other end of the third resistor R3 is connected to the source electrode of the fourth NMOS transistor MN4, the gate electrode of the fourth NMOS transistor MN4 is connected to the working voltage VINT0, the drain electrode of the fourth NMOS transistor MN4 is connected to the internal ground gnd_int, the drain electrode of the fifth NMOS transistor MN5 is connected to the positive electrode of the third diode D3, and the negative electrode of the third diode D3 is connected to the main power transistor.
2. The reverse polarity protection circuit of claim 1 wherein said input control signal is an externally input enable signal or signal ground GND.
3. The reverse polarity protection circuit according to claim 1, further comprising a second protection circuit, wherein the second protection circuit comprises a sixth NMOS tube MN6, a sixth diode D6, a fifth diode D5, a fourth resistor R4 and a power tube T2, a source electrode of the sixth NMOS tube MN6 is connected with a cathode electrode of the first diode D1, a grid electrode of the sixth NMOS tube MN6 is connected with one end of the third resistor R3, a drain electrode of the sixth NMOS tube MN6 is connected with an anode electrode of the sixth diode D6, a cathode electrode of the sixth diode D6 is connected with an anode electrode of the fifth diode D5, one end of the fourth resistor R4 and a grid electrode of the power tube T2, an anode electrode of the fifth diode D5, the other end of the fourth resistor R4 and a source electrode of the power tube T2 are connected with an OUTPUT port OUTPUT, and a drain electrode of the power tube T2 is connected with an internal power supply voltage VCC.
4. The reverse polarity protection circuit of claim 1 wherein the level signal controls the third NMOS transistor MN3 to turn off when the supply voltage VCC is positive and the load is non-inductive and when the supply voltage VCC is reverse-polar, and controls the third NMOS transistor MN3 to turn on when the supply voltage VCC is positive and the load is inductive.
5. A switch module is characterized by comprising a power supply port VCC, an OUTPUT port OUTPUT, an input port IN, an enable port SEN, a power supply circuit (110), an interface circuit (120), a control circuit (130), a main power tube and the reverse polarity protection circuit (150) according to any one of claims 1-4, The power supply circuit (110) is connected with a power supply port VCC, the power supply port VCC is connected with an external system power supply VBAT, the power supply port VCC is input into the switch module to form an internal power supply voltage VCC, and the power supply circuit (110) is used for converting the internal power supply voltage VCC into a working voltage VINT0 and supplying power for the interface circuit (120), the control circuit (130) and the polarity reversal protection circuit (150); The input end of the interface circuit (120) is connected with the input port IN and the enabling port SEN, the output end of the interface circuit is connected with the input end of the control circuit (130), and the interface circuit (120) is used for receiving the input signal of the input port IN and the enabling signal of the enabling port SEN; the output end of the control circuit (130) is connected with the grid electrode of the main power tube, the control circuit (130) is used for generating a trigger signal according to an input signal and an enabling signal, and the trigger signal is used for controlling the opening and closing of the main power tube; the input end of the reverse polarity protection circuit (150) is connected with an input control signal, and the OUTPUT end is connected with the OUTPUT port OUTPUT and the grid electrode of the main power tube; and the source electrode of the main power tube is connected with the OUTPUT port OUTPUT, and the drain electrode is connected with the power supply port VCC.
6. The switch module as claimed in claim 5, wherein the input control signal is an enable signal input from an enable port SEN or a signal ground GND.
7. The switch module of claim 5 wherein a gate of said main power tube is connected to a push-pull circuit.
8. An application circuit of a switching module, characterized in that it comprises a switching module (100) according to any of claims 5-7, a controller (200) and a load (300), The controller (200) is connected with an input port IN and an enabling port SEN, the power supply port VCC is connected with an external system power supply VBAT, one end of the load (300) is connected with an OUTPUT port OUTPUT, and the other end of the load is connected with signal ground.

Description

Reverse polarity protection circuit, switch module and application circuit thereof Technical Field The present invention relates to the field of circuit design technologies, and in particular, to a reverse polarity protection circuit, a switch module, and an application circuit thereof. Background The high-side intelligent power switch is used for replacing a relay or a fuse and is applied to a wide variety of fields, and has higher reliability and stability, smaller area and manufacturing cost compared with a traditional mechanical switch and a discrete switching device. In a typical battery powered system (e.g., automotive electronics) adequate reverse polarity protection is a necessary condition. Reliable electronic devices typically need to withstand supply voltages up to-16V (reverse voltage) for at least two minutes. The output channel of the smart power switch chip typically contains a power semiconductor switch (typically a MOSFET), wherein a load is connected into the output channel and through the semiconductor switch to the supply voltage. Accordingly, the load can switch on or off the connection path with the power supply voltage according to the on-off state of the semiconductor switch. Assuming that the on-resistance of the semiconductor switch is 100mΩ and the rated load current is 1A, the power consumption of the output channel is 100mW during normal operation. The power semiconductor switch typically has a reverse body diode in parallel with the channel current path, which body diode is in a reverse biased off state during normal operation, however, when the power source is reversed (in reverse polarity), the body diode is forward conducting and provides a reverse load current path. Assuming that the forward conduction voltage drop of the body diode is 0.7V, the power consumption of the output channel generated by the body diode conduction in the reverse polarity is 700mW, which is 7 times that in the normal operation period. This can lead to significant heat generation and even device damage. Therefore, it is necessary to design a reliable reverse polarity protection circuit to prevent this. Fig. 1 shows an example of a prior art method for implementing reverse polarity protection. In the prior art, the gate of the main power tube T1 is connected to the ground terminal through a reverse polarity protection circuit formed by the diodes D2 and D1, R2, and the ground terminal charges the gate of the main power tube T1 through the reverse polarity protection circuit and the diode D2 when in reverse polarity (the ground terminal is high voltage, for example, 16V when in reverse polarity), so that the main power tube T1 is turned on, and the power consumption of the output channel is reduced. However, when the PMOS transistor MP2 with the reverse polarity drives the inductive load, the gate voltage of the main power transistor T1 is usually clamped to-27V (example level) during the fast demagnetization stage under the normal polarity, the drain voltage of the MP2 transistor is-26.3V, and the source voltage is 0V, so the MP2 transistor needs to withstand approximately 30V. In order not to influence the back gate and source of the MP2 tube in normal operation, the isolated high-voltage P tube needs to be short-circuited, a P doped isolation region is injected on an n-type substrate in an n-substrate process, then an n-well is injected in the P doped isolation region, the n-well is taken as a substrate to serve as the isolated high-voltage P tube MP2, and a specific process is needed for realizing high withstand voltage of the high-voltage P tube with the structure. This embodiment therefore places certain demands on the choice of process. And in applications where no specific clamping protection is required internally and the schottky diode protection chip is required externally, additional packaging is required to connect to external ground potential, increasing packaging costs. Parasitic devices near the main power transistor gate and driving the transistor DMN1 are shown in fig. 2. The NMOS transistor DMN1 of the push-pull circuit is integrated in a p-doped well, the n-drain doped region-p-doped well-n-type substrate of which constitutes an npn-type parasitic transistor Q1. When the base-emitter voltage of the parasitic triode Q1 is larger than the threshold voltage, the parasitic triode Q1 is started to pull the grid potential of the main power tube to 0V, so that the starting of the main power tube is prevented, and the reverse polarity protection circuit is disabled. Disclosure of Invention The invention provides a reverse polarity protection circuit, a switch module and an application circuit thereof, which are used for solving the technical problems in the background technology. The first technical scheme of the invention is as follows, the reverse polarity protection circuit comprises a first NMOS tube MN1, a second NMOS tube MN2, a third NMOS tube MN3, a fourth NMOS tube MN4, a fifth NMO