Fault diagnosis circuit of high-side driving chip and diagnosis method thereof

Abstract

The invention belongs to the technical field of vehicle detection, and particularly provides a fault diagnosis circuit and method of a high-side driving chip, and the circuit comprises an MCU, a resistor R1, a resistor R2, a sampling resistor R3, and a diagnosis voltage Vdiag output circuit. An AD acquisition pin of an MCU does not need to be additionally occupied, when fault diagnosis is carried out on a plurality of high-side driving chips, multiple diagnosis voltage Vdiag output circuits do not need to be arranged, only the to-be-diagnosed high-side driving chips need to be connected to the diagnosis voltage Vdiag output positions of the diagnosis voltage Vdiag output circuits, and use of components is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of vehicle detection, and in particular relates to a fault diagnosis circuit of a high-side driver chip and a diagnosis method thereof. Background Art

[0002] With the development of the automobile market, the requirements for products have also increased. As an important indicator closely related to personal and property safety, functional safety standards have naturally received great attention from users and manufacturers. The current vehicle drive control circuit generally uses a high-side and low-side coordinated drive mode, with the high side controlling the PWM output and the low side acting as a safety switch for secondary protection. However, the diagnostic functions of current intelligent high-side and low-side driver chips do not support the diagnosis of all faults in a single ON / OFF state. It is necessary to build another circuit to add voltage sampling to achieve full fault diagnosis. When encountering a situation where a large number of loads need to be driven, a large number of MCU AD acquisition pin resources will be occupied for fault diagnosis.

[0003] A diagnostic circuit based on a PWM-driven intelligent high-side driver chip is disclosed in the prior art (announcement number is CN216351072U, and the announcement date is 2022.04.19), and the diagnostic circuit includes: a driving circuit, a current limiting circuit, a first diagnostic circuit, and a second diagnostic circuit: the driving circuit includes an intelligent high-side driver chip U1; the input port of the intelligent high-side driver chip U1 is connected to the IN port of the MCU through the current limiting circuit, and the first output port is connected to the IS port of the MCU through the first diagnostic circuit; the second output port of the intelligent high-side driver chip U1 is connected to the load, and the second diagnostic circuit is arranged between the intelligent high-side driver chip U1 and the load; the second diagnostic circuit includes a resistor R5 and a resistor R6; one end of the resistor R5 is respectively connected to the second output port of the intelligent high-side driver chip U1 and the load, and the other end is respectively connected to one end of the resistor R6 and the AD acquisition port of the MCU; the other end of the resistor R6 is grounded. The problem that the PWM-driven intelligent high-side driver chip cannot be correctly diagnosed due to the timing difference in current feedback is solved. The diagnostic circuit adds voltage sampling to the high side of the output driver chip to collect the output pin voltage and match it with the diagnostic pin status. This method can distinguish all faults, but it requires the MCU's AD acquisition pin resources. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a fault diagnosis circuit and a diagnosis method for a high-side driver chip to solve the above-mentioned technical problems.

[0005] In a first aspect, the present invention provides a fault diagnosis circuit for a high-side driver chip, comprising an MCU, a resistor R1, a resistor R2, a sampling resistor R3 and a diagnostic voltage Vdiag output circuit, wherein a first end of the resistor R1 is connected to a first control signal pin of the MCU, a second end of the resistor R1 is connected to an input pin of a high-side driver chip to be diagnosed, an output pin of the high-side driver chip to be diagnosed is connected to a first end of a load, a power pin of the high-side driver chip to be diagnosed and a first end of the diagnostic voltage Vdiag output circuit are both connected to an external power supply, a second end of the diagnostic voltage Vdiag output circuit is connected to a second control signal pin of the MCU, and the diagnostic voltage Vdiag output circuit is connected to a second control signal pin of the MCU. The third end of the voltage Vdiag output circuit is connected to the output pin of the high-side driver chip to be diagnosed, and outputs the diagnostic voltage Vdiag; the feedback pin of the high-side driver chip to be diagnosed is connected to the AD sampling pin of the MCU through the resistor R2, the feedback pin of the high-side driver chip to be diagnosed is grounded through the sampling resistor R3, and the feedback pin of the high-side driver chip to be diagnosed converts the current signal on the sampling resistor R3 into a voltage signal and then transmits it to the AD sampling pin of the MCU; the second end of the load is connected to the drain of the low-side protection switch Q1, the source of the low-side protection switch Q1 is grounded, and the gate of the low-side protection switch Q1 is connected to the third control signal pin of the MCU.

[0006] A further improvement of the technical solution is that it also includes a diode D1, wherein the anode of the diode D1 is connected to the third end of the diagnostic voltage Vdiag output circuit, and the cathode of the diode D1 is connected to the output pin of the high-side driver chip to be diagnosed.

[0007] A further improvement of the technical solution is that it also includes resistors R4 and R5, the cathode of the diode D1 is connected to the output pin of the high-side driver chip to be diagnosed through the resistor R4, and the output pin of the high-side driver chip to be diagnosed is grounded through the resistor R5.

[0008] A further improvement of the technical solution is that the diagnostic voltage Vdiag output circuit includes a transistor Q2 and a transistor Q3, the emitter of the transistor Q2 is connected to an external power supply, the collector of the transistor Q2 is connected to the anode of the diode D1, the base of the transistor Q2 is connected to the collector of the transistor Q3, the emitter of the transistor Q3 is grounded, and the base of the transistor Q3 is connected to the second control signal pin of the MCU.

[0009] A further improvement of the technical solution is that it also includes resistors R6 and R7, wherein the first end of resistor R6 is connected to an external power supply, the second end of resistor R6 and the first end of resistor R7 are both connected to the base of transistor Q2, and the second end of resistor R7 is connected to the collector of transistor Q3.

[0010] A further improvement of the technical solution is that it also includes a resistor R8 and a resistor R9, wherein the first end of the resistor R8 and the first end of the resistor R9 are both connected to the base of the transistor Q3, the second end of the resistor R8 is connected to the second control signal pin of the MCU, and the second end of the resistor R9 is grounded.

[0011] A further improvement of the technical solution is that the transistor Q2 is a PNP transistor.

[0012] A further improvement of the technical solution is that the transistor Q3 is an NPN transistor.

[0013] In a second aspect, the present invention provides a fault diagnosis method for a high-side driver chip, the fault diagnosis method being applicable to a fault diagnosis circuit for a high-side driver chip as described in any one of the above, comprising:

[0014] The MCU sends the working status to the high-side driver chip to be diagnosed through the first control signal pin, and controls the second control signal pin and the third control signal pin to output two interlaced voltage waveforms with a period of t;

[0015] Obtaining a voltage signal outputted from a feedback pin of the high-side driver chip to be diagnosed;

[0016] Output the corresponding voltage signal according to the working state sent; if the working state sent is OFF, the voltage signal is output in the form of a waveform; if the working state sent is ON, the voltage signal is output in the form of a truth table;

[0017] Determine the fault type under the corresponding working state based on the output truth table or waveform diagram.

[0018] A further improvement of the technical solution is that when multiple high-side driver chips are diagnosed at the same time, an isolation diode and two protection resistors are provided for each high-side driver chip to be diagnosed. The connection method of the isolation diode is the same as the connection method of the diode D1. The two protection resistors correspond to resistor R4 and resistor R5 respectively, and the connection method is also the same as the connection method of resistor R4 and resistor R5.

[0019] The beneficial effects of the present invention are that the present invention does not need to occupy the AD acquisition pin of the MCU additionally, and when performing fault diagnosis on multiple high-side driver chips, it is not necessary to set up a multi-channel diagnostic voltage Vdiag output circuit, and it is only necessary to connect the high-side driver chip to be diagnosed to the diagnostic voltage Vdiag output circuit output diagnostic voltage Vdiag (i.e., the collector of the transistor Q2), thereby reducing the use of components; in addition, the present invention is also provided with a diode D1, which can perform circuit isolation, specifically, when multiple output circuits are connected in parallel, to prevent the OUTPUT pin voltage value change caused by a fault in a certain output circuit from affecting the diagnosis of other circuits.

[0020] In addition, the invention has a reliable design principle, a simple structure and a very broad application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 This is the schematic diagram of the fault diagnosis circuit of the high-side driver chip.

[0023] Figure 2 It is a flowchart of the high-side driver chip fault diagnosis method.

[0024] Figure 3 In the OFF state, the second control signal pin MCU_PWM02 and the third control signal pin MCU_PWM03 are controlled to output two mutually staggered voltage waveforms with a period of t. Figure 4 I is the period t when a short circuit to power, short circuit to ground, or open circuit occurs in the OFF state. S The voltage waveform of the pin. Figure 5 The schematic diagram of the fault diagnosis circuit when diagnosing multiple high-side driver chips at the same time. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0027] The key terms appearing in the present invention are explained below.

[0028] MCU, short for Microcontroller Unit, means microcontroller unit in Chinese, also known as single chip microcomputer or single chip microcomputer, which appropriately reduces the frequency and specifications of the central processing unit (CPU), and integrates memory, timer, analog-to-digital conversion, universal asynchronous receiver / transmitter, programmable logic controller, direct memory access and other peripheral interfaces, and even LCD driver circuits on a single chip to form a chip-level computer, which can be used for different combination control in different application scenarios. MCU can be seen in mobile phones, remote controls, automotive electronics, industrial stepper motors, robot arm control, etc.

[0029] like Figure 1 As shown, the present invention provides a fault diagnosis circuit for a high-side driver chip, including an MCU, a resistor R1, a resistor R2, a sampling resistor R3 and a diagnostic voltage Vdiag output circuit, wherein a first end of the resistor R1 is connected to a first control signal pin of the MCU, a second end of the resistor R1 is connected to an input pin of a high-side driver chip to be diagnosed, an output pin of the high-side driver chip to be diagnosed is connected to a first end of a load, a power pin of the high-side driver chip to be diagnosed and a first end of the diagnostic voltage Vdiag output circuit are both connected to an external power supply, a second end of the diagnostic voltage Vdiag output circuit is connected to a second control signal pin of the MCU, and a diagnostic voltage The third end of the Vdiag output circuit is connected to the output pin of the high-side driver chip to be diagnosed, and outputs the diagnostic voltage Vdiag; the feedback pin of the high-side driver chip to be diagnosed is connected to the AD sampling pin of the MCU through the resistor R2, and the feedback pin of the high-side driver chip to be diagnosed is grounded through the sampling resistor R3, and the feedback pin of the high-side driver chip to be diagnosed converts the current signal on the sampling resistor R3 into a voltage signal and transmits it to the AD sampling pin of the MCU; the second end of the load is connected to the drain of the low-side protection switch Q1, the source of the low-side protection switch Q1 is grounded, and the gate of the low-side protection switch Q1 is connected to the third control signal pin of the MCU. Among them, the resistors R1 and R2 are protection resistors.

[0030] Specifically, the diagnostic voltage Vdiag output circuit includes transistors Q2 and Q3, the emitter of transistor Q2 is connected to an external power supply, the collector of transistor Q2 is connected to the positive electrode of diode D1, the base of transistor Q2 is connected to the collector of transistor Q3, the emitter of transistor Q3 is grounded, and the base of transistor Q3 is connected to the second control signal pin of MCU. Among them, transistor Q2 is a PNP transistor and transistor Q3 is an NPN transistor. In order to protect transistors Q2 and Q3, the diagnostic circuit also includes resistors R6, R7, R8 and R9, the first end of resistor R6 is connected to the external power supply, the second end of resistor R6 and the first end of resistor R7 are both connected to the base of transistor Q2, the second end of resistor R7 is connected to the collector of transistor Q3, the first end of resistor R8 and the first end of resistor R9 are both connected to the base of transistor Q3, the second end of resistor R8 is connected to the second control signal pin of MCU, and the second end of resistor R9 is grounded.

[0031] In addition, the diagnosis circuit further includes a diode D1 , the anode of the diode D1 is connected to the third terminal of the diagnosis voltage Vdiag output circuit, and the cathode of the diode D1 is connected to the output pin of the high-side driver chip to be diagnosed.

[0032] In addition, the diagnostic circuit also includes a resistor R4 and a resistor R5, the cathode of the diode D1 is connected to the output pin of the high-side driver chip to be diagnosed through the resistor R4, and the output pin of the high-side driver chip to be diagnosed is grounded through the resistor R5. The resistors R4 and R5 can play a protective role, and the resistor R4 can prevent the diagnostic voltage Vdiag from being directly connected to the ground when a short-circuit fault occurs on the output pin of the high-side driver chip to be diagnosed, and the selected values ​​of the resistors R4 and R5 should not only play a protective role, but also meet the requirement that when the diagnostic voltage Vdiag is pulled high, the output pin of the high-side driver chip to be diagnosed can obtain a voltage value equivalent to a short-circuit fault after voltage division.

[0033] like Figure 2 As shown, the present invention provides a fault diagnosis method for a high-side driver chip, which is applicable to the fault diagnosis circuit of the high-side driver chip described in any one of the above items, comprising:

[0034] Step 210, the MCU sends the working status to the high-side driver chip to be diagnosed through the first control signal pin, and controls the second control signal pin and the third control signal pin to output two interlaced voltage waveforms with a period of t;

[0035] Step 220, obtaining a voltage signal outputted from a feedback pin of the high-side driver chip to be diagnosed;

[0036] Step 230, outputting a corresponding voltage signal according to the working state sent; if the working state sent is the OFF state, the voltage signal is output in the form of a waveform; if the working state sent is the ON state, the voltage signal is output in the form of a truth table;

[0037] Step 240: determine the fault type under the corresponding working state according to the output truth table or waveform diagram.

[0038] Taking the working state sent by MCU as OFF state as an example, the second control signal pin MCU_PWM02 and the third control signal pin MCU_PWM03 are controlled to output two interlaced voltage waveforms with a period of t, such as Figure 3 As shown in the figure, the period t of the voltage applied in the OFF state is divided into four time periods, namely: Vdiag_L, Q1 is off; Vdiag_L, Q1 is on; Vdiag_H, Q1 is on; Vdiag_H, Q1 is off. The diagnostic voltage Vdiag, the output voltage Vout of the output pin of the high-side driver chip to be diagnosed, and the feedback pin I S The status is as Figure 3 In this state, I S The pin status is the normal status.

[0039] If a short circuit to power, short circuit to ground, or open circuit occurs in this state, Figure 4 As shown, the Vout voltage will present different states in the four time periods, and the corresponding I S The waveforms of the pins will show different states. It can be seen that in the OFF state, this method can be used to detect and distinguish the four states of normal state, short circuit to power, short circuit to ground, and open circuit. When short circuit to power, I S When the pin is in high state and shorted to ground, I S The pin state is 0A.

[0040] like Figure 5 As shown, when multiple high-side driver chips are diagnosed at the same time, an isolation diode (including diode D2, etc.) and two protection resistors are provided for each high-side driver chip to be diagnosed. The connection method of the isolation diode is the same as that of the diode D1. The two protection resistors correspond to resistors R4 and R5, respectively, and the connection method is also the same as that of resistors R4 and R5. There is no need to repeatedly build the diagnostic voltage Vdiag output circuit, saving electrical components. Here, the role of the diode D1 and the isolation diode (including diode D2, etc.) is to prevent the OUTPUT pin voltage value caused by the fault of a certain output circuit from affecting the diagnosis of other circuits when multiple output circuits are connected in parallel. The output circuits can be isolated by the isolation diode.

[0041] When the working state sent by the MCU is the ON state, by looking up the truth table 1, the four states of normal state, short circuit to power, short circuit to ground, and open circuit can be completely distinguished.

[0042] Truth Table 1:

[0043] Circuit Status IS Pin Status Normal state <![CDATA[I IS =I L / k ILIS ]]> Short circuit to ground <![CDATA[I IS(FAULT) ]]> Short circuit <![CDATA[I IS <I L / k ILIS ]]> open circuit <![CDATA[I IS <I IS(OL) ]]> ;

[0044] Among them, I L is the current value of normal driving load, k ILIS For I S The sampling factor of the pin, I IS(FAULT) I is the fault state S The current value on the pin, I IS(OL) is the open circuit current.

[0045] Although the present invention has been described in detail with reference to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within the scope of protection of the present invention.

Claims

1. A fault diagnosis circuit for a high-side driver chip, It is characterized in that The invention comprises an MCU, a resistor R1, a resistor R2, a sampling resistor R3 and a diagnostic voltage Vdiag output circuit, wherein the first end of the resistor R1 is connected to the first control signal pin of the MCU, the second end of the resistor R1 is connected to the input pin of the high-side driver chip to be diagnosed, the output pin of the high-side driver chip to be diagnosed is connected to the first end of the load, the power supply pin of the high-side driver chip to be diagnosed and the first end of the diagnostic voltage Vdiag output circuit are both connected to an external power supply, the second end of the diagnostic voltage Vdiag output circuit is connected to the second control signal pin of the MCU, the third end of the diagnostic voltage Vdiag output circuit is connected to the output pin of the high-side driver chip to be diagnosed, and outputs the diagnostic voltage Vdiag; the feedback pin of the high-side driver chip to be diagnosed is connected to the AD sampling pin of the MCU through the resistor R2, the feedback pin of the high-side driver chip to be diagnosed is grounded through the sampling resistor R3, the feedback pin of the high-side driver chip to be diagnosed converts the current signal on the sampling resistor R3 into a voltage signal and then transmits it to the AD sampling pin of the MCU; the second end of the load is connected to the drain of the low-side protection switch Q1, the source of the low-side protection switch Q1 is grounded, and the gate of the low-side protection switch Q1 is connected to the third control signal pin of the MCU.

2. The fault diagnosis circuit of the high-side driver chip according to claim 1, It is characterized in that It also includes a diode D1, wherein the anode of the diode D1 is connected to the third end of the diagnostic voltage Vdiag output circuit, and the cathode of the diode D1 is connected to the output pin of the high-side driver chip to be diagnosed.

3. The fault diagnosis circuit of the high-side driver chip according to claim 2, It is characterized in that It also includes a resistor R4 and a resistor R5. The cathode of the diode D1 is connected to the output pin of the high-side driver chip to be diagnosed through the resistor R4. The output pin of the high-side driver chip to be diagnosed is grounded through the resistor R5.

4. The fault diagnosis circuit of the high-side driver chip according to claim 3, It is characterized in that The diagnostic voltage Vdiag output circuit includes a transistor Q2 and a transistor Q3, the emitter of the transistor Q2 is connected to the external power supply, the collector of the transistor Q2 is connected to the anode of the diode D1, the base of the transistor Q2 is connected to the collector of the transistor Q3, the emitter of the transistor Q3 is grounded, and the base of the transistor Q3 is connected to the second control signal pin of the MCU.

5. The fault diagnosis circuit of the high-side driver chip according to claim 4, It is characterized in that It also includes a resistor R6 and a resistor R7, wherein a first end of the resistor R6 is connected to an external power supply, a second end of the resistor R6 and a first end of the resistor R7 are both connected to the base of the transistor Q2, and a second end of the resistor R7 is connected to the collector of the transistor Q3.

6. The fault diagnosis circuit of the high-side driver chip according to claim 4, It is characterized in that It also includes a resistor R8 and a resistor R9, wherein the first end of the resistor R8 and the first end of the resistor R9 are both connected to the base of the transistor Q3, the second end of the resistor R8 is connected to the second control signal pin of the MCU, and the second end of the resistor R9 is grounded.

7. The fault diagnosis circuit of the high-side driver chip according to claim 4, It is characterized in that Transistor Q2 is a PNP transistor.

8. The fault diagnosis circuit of the high-side driver chip according to claim 7, It is characterized in that Transistor Q3 is an NPN transistor.

9. A fault diagnosis method for a high-side driver chip, the fault diagnosis method being applicable to the fault diagnosis circuit of the high-side driver chip according to any one of claims 1 to 8, It is characterized in that include: The MCU sends the working status to the high-side driver chip to be diagnosed through the first control signal pin, and controls the second control signal pin and the third control signal pin to output two interlaced voltage waveforms with a period of t; Obtaining a voltage signal outputted from a feedback pin of the high-side driver chip to be diagnosed; Output the corresponding voltage signal according to the working state sent; if the working state sent is OFF, the voltage signal is output in the form of a waveform; if the working state sent is ON, the voltage signal is output in the form of a truth table; Determine the fault type under the corresponding working state based on the output truth table or waveform diagram.

10. The fault diagnosis circuit of the high-side driver chip according to claim 9, It is characterized in that When diagnosing multiple high-side driver chips at the same time, an isolation diode and two protection resistors are provided for each high-side driver chip to be diagnosed. The connection method of the isolation diode is the same as that of the diode D1. The two protection resistors correspond to resistor R4 and resistor R5 respectively, and the connection method is also the same as that of resistor R4 and resistor R5.

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