A high-side load drive circuit

Abstract

This invention relates to a high-side load driving circuit. The driving circuit drives the load on the high side, with the other end of the load grounded. The driving circuit includes a power supply and current sensing module, a low-side driving chip, a first pull-up resistor, a PMOS transistor, an NPN transistor, a current sensing resistor, a second resistor, a clamping module, and a feedback module. The base of the NPN transistor is connected to the connection port of the low-side driving chip. The collector of the NPN transistor is connected to the power supply through the first pull-up resistor and is connected to the gate of the PMOS transistor. The emitter of the NPN transistor is connected to the second resistor and then grounded. The clamping module is connected in parallel with the first pull-up resistor. The source of the PMOS transistor is connected to the power supply, and the drain is connected to the current sensing resistor and then to the load. One end of the feedback module is connected to the other connection port of the low-side driving chip, and the other end is connected to the output terminal of the current sensing resistor. Compared with the prior art, this invention has the advantages of small area, low cost, and ease of implementation.

Description

Technical Field

[0001] This invention relates to the field of load drive circuit technology, and more particularly to a high-side load drive circuit. Background Technology

[0002] In the current automotive industry, low-side drives within a vehicle system are typically used for powertrain-related loads such as motors and heaters. High-side drives are frequently used for fuel pumps and body-related functions such as seats, lighting, wipers, and fans. Within a vehicle system, high-side drive circuits are used less frequently than low-side drive circuits.

[0003] Currently available technologies mostly rely on mature high-side driver chips to drive high-side load circuits. For example, utility model patent CN216351072U discloses a diagnostic circuit based on a PWM-driven intelligent high-side driver chip. The input port of the intelligent high-edge driver chip U1 is connected to the IN port of the MCU through the voltage divider circuit; the first output port of the intelligent high-edge driver chip U1 is connected to the Is port of the MCU through the first diagnostic circuit; the second output port of the intelligent high-edge driver chip U1 is connected to the load, and the second diagnostic circuit is disposed between the intelligent high-edge driver chip U1 and the load; the first diagnostic circuit includes resistors R2 and R3; one end of resistor R2 is connected to the Is port of the MCU, and the other end is connected to the first output port of the intelligent high-edge driver chip U1 and one end of resistor R3 respectively; the second diagnostic circuit includes resistors R5 and R6; one end of resistor R5 is connected to the second output port of the intelligent high-edge driver chip U1 and the load respectively, and the other end is connected to one end of resistor R6 and the AD acquisition port of the MCU respectively; the voltage divider circuit includes resistor R1; one end of resistor R1 is connected to the IN port of the MCU, and the other end is connected to the input port of the intelligent high-edge driver chip U1. The driving circuit further includes a diode D1 and a resistor R4; one end of the resistor R4 is connected to the ground terminal of the intelligent high-edge driving chip U1, and the other end is grounded; the anode of the diode D1 is connected to the ground terminal of the intelligent high-edge driving chip U1 and one end of the resistor R4. The diagnostic circuit further includes a filtering circuit; the filtering circuit is disposed between the intelligent high-edge driving chip U1 and the load. The filtering circuit includes a capacitor C1; one end of the capacitor C1 is connected to the second output port of the intelligent high-edge driving chip U1 and the load.

[0004] Existing technologies can solve the problem of PWM-driven intelligent high-side drive chips failing to diagnose correctly due to timing differences in current feedback. The drawback is that while high-side drive circuits are used less frequently in automobiles, intelligent high-side drive chips are expensive, and the diagnostic circuits based on them occupy a large area, increasing PCB board space and overall cost. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art and provide a high-side load drive circuit.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A high-side load driving circuit is disclosed, wherein the driving circuit drives the load on the high side. The driving circuit includes a power supply and further includes a low-side driving chip with multiple connection ports, a first pull-up resistor, a PMOS transistor, an NPN transistor, a clamping module, and a feedback module.

[0008] The base of the NPN transistor is connected to one of the connection ports of the low-side driver chip, which provides a drive signal to the NPN transistor. The emitter of the NPN transistor is grounded, and the collector of the NPN transistor is connected to the power supply through a first pull-up resistor. The collector of the NPN transistor is also connected to the gate of the PMOS transistor. The anode of the clamping module is connected to the connection line between the collector of the NPN transistor and the gate of the PMOS transistor. The cathode of the clamping module is connected to the power supply.

[0009] The source of the PMOS transistor is connected to the power supply, the drain of the PMOS transistor is connected to the load, and the other end of the load is grounded.

[0010] In a preferred embodiment, the driving circuit further includes a feedback module, which includes a second pull-up resistor, a PNP transistor, a first resistor, a third resistor, and a feedback resistor.

[0011] The collector of the PNP transistor is connected to the feedback resistor and then grounded. The connection line between the collector of the PNP transistor and the feedback resistor is also connected to another connection port of the low-side driver chip through a branch. The emitter of the PNP transistor is connected to the power supply through a second pull-up resistor. The base of the PNP transistor is connected to the first resistor and the drain of the PMOS transistor in sequence. The connection line between the first resistor and the drain of the PMOS transistor is also connected to a third resistor through a branch. The other end of the third resistor is grounded. The low-side driver chip performs fault diagnosis based on the voltage of the feedback resistor.

[0012] In a preferred embodiment, the resistance values ​​of the second pull-up resistor and the feedback resistor satisfy the following conditions:

[0013]

[0014] In the formula, R3 is the resistance value of the second pull-up resistor, R 13 U is the resistance value of the feedback resistor. ECU U1 is the power supply voltage, U1 is the load-to-ground short-circuit fault threshold set by the driver chip for PNP transistor conduction, and β is the current amplification factor of the PNP transistor.

[0015] In a preferred embodiment, the driving circuit further includes a current detection module, which includes a main control chip, a filter module, and a current detection amplification module connected in sequence. A current detection resistor is provided between the drain of the PMOS transistor and the load. The current detection amplification module and the two ends of the current detection resistor are connected together. The filter module includes a filter resistor whose two ends are respectively connected to the main control chip and the current detection amplification module. A filter capacitor is connected through a branch in the connection line between the filter resistor and the main control chip. The other end of the filter capacitor is grounded.

[0016] In a preferred embodiment, the current detection amplification module is a current detection amplification chip.

[0017] In a preferred embodiment, the main control chip is a chip with 12-bit AD sampling accuracy.

[0018] In a preferred embodiment, the clamping module is a clamping diode.

[0019] In a preferred embodiment, the NPN transistor is connected to a second resistor before its emitter is grounded.

[0020] In a preferred embodiment, the power source is the internal power source of the ECU.

[0021] In a preferred embodiment, the low-side load drive circuit is packaged in the ECU.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1) The high-side load driving circuit built by the low-side driving chip in this invention saves the cost of the high-side driving chip compared to using an intelligent high-side driving chip.

[0024] 2) This invention employs a feedback module and a current detection module to achieve real-time monitoring of the output terminal, diagnosis of electrical faults in the load, and closed-loop control of the current. Furthermore, the actual faults in the load can be determined through dual diagnosis.

[0025] 3) The driving circuit design of the present invention is more compact, and the overall PCB board area is smaller than that of the existing technology.

[0026] 4) The drive circuit design of this invention is simple in terms of wiring and does not require special components, making it easy to implement. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the present invention.

[0028] The numbers in the diagram are as follows:

[0029] 1. Low-side driver chip; 2. First pull-up resistor; 3. Second pull-up resistor; 4. Clamping diode; 5. PMOS transistor; 6. NPN transistor; 7. Current sensing resistor; 8. PNP transistor; 9. First resistor; 10. Second resistor; 11. Third resistor; 12. Load; 13. Feedback resistor; 14. Main control chip; 15. Filter capacitor; 16. Filter resistor; 17. Current sensing amplifier chip; 18. ECU internal power supply. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0031] like Figure 1 As shown, this embodiment provides a low-side load drive circuit with circuit integrity detection and open-circuit diagnosis functions, including a low-side drive chip 1, a first pull-up resistor 2, a second pull-up resistor 3, a clamping diode 4, a PMOS transistor 5, an NPN transistor 6, a current sensing resistor 7, a PNP transistor 8, a first resistor 9, a second resistor 10, a third resistor 11, a load 12, a feedback resistor 13, a main control chip 14, a filter capacitor 15, a filter resistor 16, a current detection amplifier chip 17, and a power supply. The low-side drive chip 1 is a low-side drive chip C3MIO, the main control chip 14 has 12-bit AD sampling accuracy, and the power supply is the ECU's internal power supply 18.

[0032] One end of the load 12 is grounded, and the other end is sampled by the current sensing resistor 7. The voltage across the current sensing resistor 7 is processed by the current detection amplifier chip 17, filtered by the filter circuit composed of the filter resistor 16 and the filter capacitor 15, and then sent to the main control chip 14. The main control chip monitors the current passing through the load 12 in real time.

[0033] One end of the current sensing resistor 7 is connected to the drain (output terminal) of PMOS transistor 5. The PWM level wave provided by the low-side driver chip 1 controls the conduction state of NPN transistor 6. When the output level of the low-side driver chip 1 is low, NPN transistor 6 is not turned on, the gate voltage of PMOS transistor 5 is the voltage of the internal power supply 18 of the ECU, and PMOS transistor 5 is not turned on. When the output level of the low-side driver chip 1 is high, NPN transistor 6 is turned on, the gate voltage of PMOS transistor 5 is pulled down, and PMOS transistor 5 is turned on. This realizes the PWM wave output of PMOS transistor 5. At the same time, the output terminal of PMOS transistor 5 is fed back to the low-side driver chip 1 in sequence through the current sensing resistor 7, the first resistor 9, and PNP transistor 8, realizing real-time monitoring of the output terminal and diagnosis of electrical faults in the load.

[0034] In this embodiment, the output terminal of the current sensing resistor 7 is monitored and diagnosed in real time by the main control chip 14 and the low-side driver chip 1 simultaneously. Through dual monitoring and diagnosis, the actual load fault can be finally determined.

[0035] The cathode of clamping diode 4 is connected to the source of PMOS transistor 5, and the anode is connected to the gate of PMOS transistor 5, thereby clamping the voltage difference between the G and S terminals of PMOS transistor 5 and providing circuit protection and load protection.

[0036] One end of the pull-up resistor 2 is connected to the internal power supply 18 of the ECU, and the other end is connected between the output terminal of the NPN transistor 6 and the gate of the PMOS transistor 5.

[0037] One end of the pull-up resistor 3 is connected to the internal power supply 18 of the ECU, and the other end is connected to the emitter of the PNP transistor 8.

[0038] Low-side driver chip 1 enables the base of NPN transistor 6, outputting a PWM wave, and the resistance value of resistor 11 is much larger than the resistance value of load 12. When load 12 is working normally, the base voltage of PNP transistor 8 is high, which is the cutoff state, and low-side driver chip 1 does not report a fault. Resistor 11 and load 12 are in parallel, and the resistance value of the parallel circuit is approximately equal to the resistance value of load 12. The main control chip 14 monitors the voltage across the current sensing resistor 7 through the current sensing amplifier chip 17, which is approximately:

[0039]

[0040] In the formula, U7 is the voltage across the current sensing resistor 7 monitored by the main control chip 14, R7 is the resistance value of the current sensing resistor 7, and R 12 U is the resistance value of load 12. ECU D is the internal power supply voltage, A is the duty cycle of the output PWM wave, and A is the amplification factor of the current sensing amplifier chip.

[0041] When load 12 is open, PMOS transistor 5 is in the on state, and the base voltage of PNP transistor 8 is high, indicating it is in the off state. Low-side driver chip 1 does not report a fault. The main control chip 14 monitors the voltage across current sensing resistor 7 through current sensing amplifier chip 17 as follows:

[0042]

[0043] In the formula, U7 is the voltage across the current sensing resistor 7 monitored by the main control chip 14, R7 is the resistance value of the current sensing resistor 7, and R 11 U is the resistance value of resistor 11. ECU D is the internal power supply voltage, D is the duty cycle of the output PWM wave, and A is the amplification factor of the current sensing amplifier chip. When the circuit is open, the voltage across the current sensing resistor monitored by the current sensing module is lower than the voltage across the current sensing resistor when the circuit is operating normally. Based on the lower voltage value monitored by the current sensing module and the fact that the low-side driver chip 1 does not report a fault, the circuit fault can be determined to be that the load is in an open-circuit state.

[0044] The values ​​of the second pull-up resistor 3 and the feedback resistor 13 are selected based on the threshold of the channel's short-circuit fault to ground.

[0045]

[0046] Right now,

[0047]

[0048] In the formula, R3 is the resistance value of pull-up resistor 3, U1 is the load-to-ground short-circuit fault threshold set by the driver chip for PNP transistor 8 to conduct, and R 13 For the resistance value of feedback resistor 13, U ECU β is the internal power supply voltage, and β is the current amplification factor of the PNP transistor 8.

[0049] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A high-side load driving circuit which drives a load (12) on the high side, said driving circuit comprising a power supply, characterized in that, The driving circuit further comprises a low-side driving chip (1) provided with a plurality of connection ports, a first pull-up resistor (2), a PMOS tube (5), an NPN triode (6), a clamping module, a feedback module and a current detection module; The base of the NPN triode (6) is connected with one of the connection ports of the low-side driving chip (1), the low-side driving chip (1) provides a driving signal for the NPN triode (6), the emitter of the NPN triode (6) is grounded, the collector of the NPN triode (6) is connected with the power supply through the first pull-up resistor (2), and the collector of the NPN triode (6) is further connected with the gate of the PMOS tube (5); the anode of the clamping module is connected with the connecting line between the collector of the NPN triode (6) and the gate of the PMOS tube (5), and the cathode of the clamping module is connected with the power supply. The source of the PMOS tube (5) is connected with the power supply, the drain of the PMOS tube (5) is connected with a load (12), and the other end of the load (12) is grounded. The feedback module comprises a second pull-up resistor (3), a PNP triode (8), a first resistor (9), a third resistor (11) and a feedback resistor (13); the collector of the PNP triode (8) is connected with the feedback resistor (13) and then grounded, the connecting line between the collector of the PNP triode (8) and the feedback resistor (13) is further connected with the other connection port of the low-side driving chip (1) through a branch, the emitter of the PNP triode (8) is connected with the power supply through the second pull-up resistor (3), the base of the PNP triode (8) is connected with the drain of the PMOS tube (5) in sequence, the connecting line between the first resistor (9) and the drain of the PMOS tube (5) is further connected with the third resistor (11) through a branch, and the other end of the third resistor (11) is grounded; the low-side driving chip (1) performs fault diagnosis based on the voltage of the feedback resistor (13). The current detection module comprises a main control chip (14), a filtering module and a current detection amplification module connected in sequence, the drain of the PMOS tube (5) is provided with a current detection resistor (7) between the load (12), the current detection amplification module and the current detection resistor (7) are connected at two ends, the filtering module comprises a filtering resistor (16) connected with the main control chip (14) and the current detection amplification module at two ends, and the connecting line between the filtering resistor (16) and the main control chip (14) is connected with a filtering capacitor (15) through a branch, and the other end of the filtering capacitor (15) is grounded.

2. A high-side load driver circuit according to claim 1, wherein, The resistance values of the second pull-up resistor (3) and the feedback resistor (13) satisfy the following condition: wherein R3 is the resistance value of the second pull-up resistor (3), Rf is the resistance value of the feedback resistor (13), Vcc is the power supply voltage, Vth is the load-to-ground short-circuit fault threshold for which the PNP transistor (8) provided in the driver chip is turned on, β is the current amplification factor of the PNP transistor (8).

3. The high-side load driver circuit of claim 1, wherein, The current detection amplification module is a current detection amplification chip (17).

4. The high-side load driver circuit of claim 1, wherein, The main control chip (14) is a chip with 12-bit AD sampling accuracy.

5. The high-side load driver circuit of claim 1, wherein, The clamping module is a clamping diode (4).

6. The high-side load driver circuit of claim 1, wherein, The emitter of the NPN triode (6) is further connected with a second resistor (10) before being grounded.

7. The high-side load driver circuit of claim 1, wherein, The power supply is an ECU internal power supply (18).

8. The high-side load driver circuit of claim 1, wherein, The low-side load driving circuit is packaged in the ECU.

Images