High-side switch control circuit with dual-point failure protection

Abstract

The application discloses a high-side switch control circuit with double-point failure protection function, which comprises a plurality of first switch circuits, second switch circuits, switch tube protection driving circuits and protection circuits. Each first switch circuit comprises a first switch tube Q1 and a second switch tube Q2 connected back to back, and a third switch tube Q3 and a fourth switch tube Q4 connected back to back; the second switch circuit comprises a fifth switch tube Q5 and a sixth switch tube Q6 connected back to back, and a seventh switch tube Q7 and an eighth switch tube Q8 connected back to back. The first input end of the protection circuit is connected with the common connection point of Q7 and Q8, the plurality of second input ends are respectively connected with the common connection points of the third switch tube Q3 and the fourth switch tube Q4 of the plurality of first switch circuits, and the output end is connected with the input end of the switch tube protection driving circuit. When double-point failure is detected, the high-side switch control circuit enters a safe state, so that the influence of double-point failure is weakened and controlled.

Description

Technical Field

[0001] This invention relates to electronic circuit technology, and more particularly to a high-side switch control circuit that can be connected to a backup power supply. Background Technology

[0002] Figure 1 A schematic diagram of an onboard high-side switch control circuit 100 that can be connected to a backup power supply is shown. Figure 1 As shown, the vehicle-mounted high-side switch control circuit 100 includes a first switch circuit for connecting to KL30_0 and a second switch circuit for connecting to KL30_1. KL30_0 is a non-functional safety-related supply voltage (i.e., the first conventional supply voltage) used to power the non-functional safety-related controller, and KL30_1 is a functional safety-related supply voltage (i.e., the second conventional supply voltage) used to power the functional safety-related controller. KL30_0 and KL30_1 are voltages formed by passing the positive terminal voltage of the vehicle battery through different fuses and relays. The first switch circuit includes a first switch Q1 and a second switch Q2 connected back-to-back, and a third switch Q3 and a fourth switch Q4 connected back-to-back. The second switch circuit includes a fifth switch Q5 and a sixth switch Q6 connected back-to-back, and a seventh switch Q7 and an eighth switch Q8 connected back-to-back. The vehicle-mounted high-side switch control circuit 100 is not normally connected to the backup power supply Emergency_feed. When KL30_0 or KL30_1 fails, both the first and second switch circuits are switched to be powered by the backup power supply Emergency_feed. At this time, the switching control module (not shown in the figure) controls the first switch Q1 and the second switch Q2 of the first switch circuit to turn off, and simultaneously controls the third switch Q3 and the fourth switch Q4 to turn on. In addition, it controls the fifth switch Q5 and the sixth switch Q6 of the second switch circuit to turn off, and simultaneously controls the seventh switch Q7 and the eighth switch Q8 to turn on.

[0003] Due to safety concerns, the functional safety integrity level (ASIL) of the on-board high-side switch control circuit that can be connected to a backup power supply is typically required to be ASIL D or ASIL C. By design, a failure in the non-functional safety-related power supply KL30_0, such as overvoltage or undervoltage, must not affect the functional safety-related power supply KL30_1, such as causing it to overvoltage or undervoltage.

[0004] When both the fourth switch Q4 and the seventh switch Q7 fail due to a short circuit, a dual-point failure is constituted, referred to here as the first dual-point failure. Figure 2As shown. In the event of a first double-point failure, if KL30_0 is overvoltage, it will form a circuit path through the first double-point failure (e.g. Figure 2 As shown by the arrow in the image, injecting current into KL30_1 causes its voltage to rise, i.e., overvoltage.

[0005] When both the third switch Q3 and the eighth switch Q8 fail due to a short circuit, a second dual-point failure is constituted, referred to here as the second dual-point failure. Figure 3 As shown. In the event of a second double-point failure, if KL30_0 is undervoltage, it will form a circuit path through the second double-point failure (e.g. Figure 3 (As shown by the arrow in the image), KL30_0 draws current from KL30_1, causing KL30_1 to be undervoltage.

[0006] Figure 2 and Figure 3 The principle of double-point failure is illustrated by taking a vehicle-mounted high-side switch control circuit with one first switch circuit as an example. When the vehicle-mounted high-side switch control circuit has multiple first switch circuits, the principle of double-point failure is similar.

[0007] Functional safety ASIL C and ASIL D levels do not allow for the existence of double-point failures. If the first or second double-point failure mentioned above occurs, it will lead to a violation of the safety objective (KL30_1 overvoltage or undervoltage) and bring about a major safety hazard. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a high-side switch control circuit that can detect double-point failures in a timely manner, and when a double-point failure is detected, the high-side switch control circuit enters a safe state within the fault tolerance time, thereby reducing and controlling the impact of double-point failures.

[0009] This invention provides a high-side switch control circuit with dual-point failure protection, comprising: a backup power supply voltage input terminal for connecting the output voltage of the backup power supply; several first switch circuits, each first switch circuit including a first switch Q1 and a second switch Q2 connected back-to-back, and a third switch Q3 and a fourth switch Q4 connected back-to-back; the first terminal of the first switch Q1 is connected to a first conventional power supply voltage, and the second terminal of the first switch Q1 is connected to the second terminal of the second switch Q2; the first terminal of the third switch Q3 is connected to the backup power supply voltage input terminal, and the third switch Q4... The second terminal is connected to the second terminal of the fourth switch Q4. The first terminal of the fourth switch Q4 and the first terminal of the second switch Q2 are both connected to the first common node P1, which serves as the output terminal of the first switching circuit. The second switching circuit includes a fifth switch Q5 and a sixth switch Q6 connected back-to-back, and a seventh switch Q7 and an eighth switch Q8 connected back-to-back. The first terminal of the fifth switch Q5 is used to connect to the second conventional power supply voltage, and the second terminal of the fifth switch Q5 is connected to the second terminal of the sixth switch Q6. The first terminal of the seventh switch Q7 is connected to the backup power supply voltage input terminal. The second terminal of transistor Q7 is connected to the second terminal of the eighth switch transistor Q8. The first terminals of the eighth switch transistor Q8 and the sixth switch transistor Q6 are both connected to the second common node P2, which serves as the output terminal of the second switching circuit. A switch protection drive circuit is also included, with its output terminal connected to the control terminals of the fifth switch transistor Q5 and the sixth switch transistor Q6, respectively. A protection circuit has its first input terminal connected to the common junction of the second terminals of the seventh switch transistor Q7 and the eighth switch transistor Q8. Several second input terminals of the protection circuit are correspondingly connected to the third input terminals of several first switching circuits. The common junction of the second terminal of switch Q3 and the second terminal of switch Q4 is connected to the third input terminal of the protection circuit, which is connected to the backup power supply voltage input terminal. The output terminal of the protection circuit is connected to the input terminal of the switch protection drive circuit. The protection circuit is used to latch the fifth switch Q5 and the sixth switch Q6 into the off state through the switch protection drive circuit when it detects that the voltage of the common junction of the second terminal of the seventh switch Q7 and the second terminal of the eighth switch Q8 is greater than a preset first voltage threshold, and the voltage of the common junction of the second terminal of the third switch Q3 and the second terminal of the fourth switch Q4 in any first switch circuit is greater than a preset second voltage threshold.

[0010] This invention has at least the following technical effects:

[0011] 1. The protection circuit of this invention performs real-time detection of double-point failure. Once a double-point failure occurs, the high-side switch control circuit enters a safe state within the fault tolerance time, turning off the fifth switch Q5 and the sixth switch Q6, thereby achieving reliable protection of the power supply of the controller related to functional safety.

[0012] 2. The high-side switching circuit of this invention is composed of discrete components, which is inexpensive. Attached Figure Description

[0013] Figure 1 A schematic diagram of a high-side switch control circuit that can be connected to a backup power supply is shown.

[0014] Figure 2 A schematic diagram of a two-point failure in the first scenario is shown in the high-side switch control circuit that can be connected to a backup power supply.

[0015] Figure 3 A schematic diagram is shown of a two-point failure in the second scenario of a high-side switch control circuit that can be connected to a backup power supply.

[0016] Figure 4 A circuit diagram of a high-side switch control circuit with dual-point failure protection according to an embodiment of the present invention is shown.

[0017] Figure 5 A circuit diagram of a protection circuit according to a first embodiment of the present invention is shown.

[0018] Figure 6 A circuit diagram of a protection circuit according to a second embodiment of the present invention is shown. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0020] Figure 4 A circuit schematic diagram of a high-side switch control circuit with dual-point failure protection according to an embodiment of the present invention is shown. Please refer to [link / reference]. Figure 4 According to an embodiment of the present invention, a high-side switch control circuit 200 with dual-point failure protection includes a backup power supply voltage input terminal 200A, two first switch circuits 1 and 2, a switch transistor protection drive circuit 3 and a protection circuit 4.

[0021] The 200A backup power supply voltage input terminal is used to connect to the output voltage Emergecy_feed of the backup power supply.

[0022] Each first switching circuit 1 includes a first switching transistor Q1 and a second switching transistor Q2 connected back-to-back, and a third switching transistor Q3 and a fourth switching transistor Q4 connected back-to-back. The first terminal of the first switching transistor Q1 is used to connect to a first conventional power supply voltage (in this embodiment, the first conventional power supply voltage is the non-functional safety related power supply voltage KL30_0 of the vehicle power supply), and the second terminal of the first switching transistor Q1 is connected to the second terminal of the second switching transistor Q2; the first terminal of the third switching transistor Q3 is connected to the backup power supply voltage input terminal 200A, and the second terminal of the third switching transistor Q3 is connected to the second terminal of the fourth switching transistor Q4. The first terminals of the fourth switching transistor Q4 and the second switching transistor Q2 are both connected to a first common node P1, and the first common node P1 serves as the output terminal of the first switching circuit 1.

[0023] The second switching circuit 2 includes a fifth switch Q5 and a sixth switch Q6 connected back-to-back, and a seventh switch Q7 and an eighth switch Q8 connected back-to-back. The first terminal of the fifth switch Q5 is used to connect to the second conventional power supply voltage (in this embodiment, the second conventional power supply voltage is the functional safety-related power supply voltage KL30_1 of the vehicle power supply), and the second terminal of the fifth switch Q5 is connected to the second terminal of the sixth switch Q6; the first terminal of the seventh switch Q7 is connected to the backup power supply voltage input terminal 200A, and the second terminal of the seventh switch Q7 is connected to the second terminal of the eighth switch Q8. The first terminals of the eighth switch Q8 and the sixth switch Q6 are both connected to the second common node P2, which serves as the output terminal of the second switching circuit.

[0024] In this embodiment, the first switch Q1 to the eighth switch Q8 are all NMOS transistors. The gate, drain and source of the NMOS transistors constitute the control terminal, the first terminal and the second terminal of the switch transistors, respectively.

[0025] The output terminal of the switch protection drive circuit 3 is connected to the control terminal of the fifth switch Q5 and the control terminal of the sixth switch Q6, respectively.

[0026] The first input terminal of the protection circuit 4 is connected to the common junction of the second terminals of the seventh switch Q7 and the eighth switch Q8. Several second input terminals of the protection circuit 4 are respectively connected to the common junctions of the second terminals of the third switch Q3 and the fourth switch Q4 of several first switch circuits 1. The third input terminal of the protection circuit 4 is connected to the backup power supply voltage input terminal 200A. The output terminal of the protection circuit is connected to the input terminal of the switch protection drive circuit 3. The protection circuit 4 is used to latch the fifth switch Q5 and the sixth switch Q6 into a turned-off state through the switch protection drive circuit 3 when the voltage at the common junction of the second terminals of the seventh switch Q7 and the eighth switch Q8 exceeds a preset first voltage threshold, and the voltage at the common junction of the second terminals of the third switch Q3 and the fourth switch Q4 of any first switch circuit 1 exceeds a preset second voltage threshold (i.e., when a double-point failure is detected). This allows the high-side switch control circuit to enter a safe state. In this safe state, the power network KL30_1 related to functional safety is within a voltage range that does not pose a danger to functional safety. Electrical equipment (including controllers) or power supply networks that pose a risk to the power network security are isolated from the power network KL30_1 related to functional safety.

[0027] Figure 5 A circuit diagram of a protection circuit according to a first embodiment of the present invention is shown. Please refer to... Figure 5 In this embodiment, the protection circuit 4 includes a shutdown latch circuit 40, a first disable circuit 41, and a second disable circuit 42.

[0028] The first input terminal of the shutdown latch circuit 40 serves as the first input terminal of the protection circuit 4, and is connected to the common junction of the second terminals of the seventh switch Q7 and the eighth switch Q8. The output terminal of the shutdown latch circuit 40 is connected to the input terminal of the switch protection drive circuit 3. The shutdown latch circuit 40 is used to latch the fifth switch Q5 and the sixth switch Q6 into a shutdown state through the switch protection drive circuit 3 when the voltage at the common junction of the second terminals of the seventh switch Q7 and the eighth switch Q8 is detected to be greater than a preset first voltage threshold.

[0029] The first input terminal of the first disable circuit 41 serves as the third input terminal of the protection circuit 4 and is connected to the backup power supply voltage input terminal 200A. The output terminal of the first disable circuit 41 is connected to the second input terminal of the shutdown latch circuit 40. The first disable circuit 41 is used to disable the shutdown latch circuit 40 when the output voltage Emergecy_feed of the backup power supply is detected.

[0030] The two input terminals of the second disable circuit 42 (i.e. the second input terminal of the protection circuit 4) are respectively connected to the common junction of the second terminal of the third switch transistor Q3 and the second terminal of the fourth switch transistor Q4 of the two first switch circuits 1. The output terminal of the second disable circuit 42 is connected to the second input terminal of the first disable circuit 41. The second disable circuit 42 is used to disable the first disable circuit 41 when the voltage at the common junction of the second terminal of the third switch transistor Q3 and the second terminal of the fourth switch transistor Q4 of any first switch circuit is greater than a preset second voltage threshold.

[0031] The time t1 taken for the second disable circuit 42 to detect that the common junction voltage of the second terminal of the third switch Q3 and the second terminal of the fourth switch Q4 in any one of the first switch circuits is greater than the preset second voltage threshold, the time t2 taken for the first disable circuit 41 to detect that the output voltage of the backup power supply is connected, and the time t3 taken for the turn-off latch circuit to detect that the common junction voltage of the second terminal of the seventh switch Q7 and the second terminal of the eighth switch Q8 is greater than the preset first voltage threshold satisfy the following relationship: t1 < t2 < t3.

[0032] The shutdown latch circuit 40 includes switching transistors Q11, Q12, and Q13, a first RC filter circuit, a first voltage divider circuit, resistors R3, R5, R6, R7, and R8. The first RC filter circuit includes resistor R1 and capacitor C1, and the first voltage divider circuit includes resistors R2 and R4.

[0033] The input terminal of the first RC filter circuit is connected to the first input terminal of the turn-off latch circuit 40. The output terminal of the first RC filter circuit is connected to the input terminal of the first voltage divider circuit. The output terminal of the first voltage divider circuit is connected to the control terminal of the switching transistor Q12 and one end of the resistor R3. The other end of the resistor R3 is connected to the first terminal of the switching transistor Q11.

[0034] The second terminal of switch Q11 is connected to the power supply of the shutdown latch circuit and one end of resistor R5. The common connection point of the other end of resistor R5 and one end of resistor R6 is connected to the control terminal of switch Q11. The other end of resistor R6 is connected to the first terminal of switch Q12, and the second terminal of switch Q12 is grounded. In this embodiment, the power supply of the shutdown latch circuit is the output voltage KL30_1 of the second conventional power supply.

[0035] One end of resistor R7 is connected to the common junction of the other end of resistor R3 and the first terminal of switching transistor Q11. The common junction of the other end of resistor R7 and one end of resistor R8 is connected to the control terminal of switching transistor Q13. The other end of resistor R8 is grounded. The first terminal of switching transistor Q13 serves as the output terminal of the turn-off latch circuit 40, and the second terminal of switching transistor Q13 is grounded.

[0036] In this first embodiment, switch Q12 is an NPN transistor, with its base, collector, and emitter forming its control terminal, first terminal, and second terminal, respectively. Switch Q11 is a PNP transistor, with its base, collector, and emitter forming its control terminal, first terminal, and second terminal, respectively. Switch Q13 is an NMOS transistor, with its gate, drain, and source forming its control terminal, first terminal, and second terminal, respectively.

[0037] The first disable circuit 41 includes a second RC filter circuit, a second voltage divider circuit, and a switching transistor Q14. The second RC filter circuit includes a resistor R9 and a capacitor C2, and the second voltage divider circuit includes a resistor R10 and a resistor R11.

[0038] The input of the second RC filter circuit is connected to the 200A backup power supply voltage input. The output of the second RC filter circuit is connected to the input of the second voltage divider circuit. The output of the second voltage divider circuit is connected to the control terminal of the switching transistor Q14. The first terminal of the switching transistor Q14 is connected to the control terminal of the switching transistor Q12, and the second terminal of the switching transistor Q14 is grounded. When the second RC filter circuit is connected to the backup power supply output voltage Emergecy_feed, the switching transistor Q14 is turned on.

[0039] In this first embodiment, the switching transistor Q14 is an NPN transistor, and the base, collector, and emitter of the NPN transistor Q14 constitute the control terminal, the first terminal, and the second terminal of the switching transistor Q14, respectively.

[0040] The second power-disabling circuit 42 includes two diodes D1 (the number of diodes D1 is the same as the number of diodes in the first switching circuit 1), a third RC filter circuit, a third voltage divider circuit, and a switching transistor Q15. The third RC filter circuit includes a resistor R12 and a capacitor C3, and the third voltage divider circuit includes a resistor R13 and a resistor R14.

[0041] The anodes of the two diodes D1 are connected one-to-one to the common junction of the second terminals of the third switch Q3 and the fourth switch Q4 in the two first switching circuits. The common junction of the cathodes of the two diodes D1 is connected to the input terminal of the third RC filter circuit. The output terminal of the third RC filter circuit is connected to the input terminal of the third voltage divider circuit. The output terminal of the third voltage divider circuit is connected to the control terminal of switch Q15. The first terminal of switch Q15 is connected to the control terminal of switch Q14, and the second terminal of switch Q15 is grounded.

[0042] In this first embodiment, the switching transistor Q15 is an NPN transistor, and the base, collector, and emitter of the NPN transistor Q15 constitute the control terminal, the first terminal, and the second terminal of the switching transistor Q15, respectively.

[0043] The aforementioned first to third RC filter circuits have a filtering function, which can improve the circuit's anti-interference ability and filter out pulses that cause false triggering. Interference comes from transients, such as the moment of switching, the moment of power-on, or interference from other electrical appliances operating in the vehicle. The time constant of the third RC filter circuit is smaller than the time constant of the second RC filter circuit, and the time constant of the second RC filter circuit is smaller than the time constant of the first RC filter circuit, thus making t1 < t2 < t3.

[0044] When the output voltage Emergecy_feed of the backup power supply is not connected and a double-point failure occurs, the common junction voltage of the second terminal of the third switch Q3 and the second terminal of the fourth switch Q4 in at least one of the first switching circuits 1 will be greater than the turn-on voltage of switch Q15. Switch Q5 will turn on, thereby disabling the first disable circuit 41. After the first disable circuit 41 is disabled, it can no longer disable the latch circuit. When a double-point failure occurs, the common junction voltage KL30_1_Emer_S of the second terminal of the seventh switch Q7 and the second terminal of the eighth switch Q8 is greater than the preset first voltage threshold. Switch Q12 will turn on, and the voltage at the control terminal of switch Q11 will become low, and switch Q11 will also turn on. After switch Q11 is turned on, switch Q13 also turns on. The switch protection drive circuit 3 receives the level signal output by switch Q13 and turns off the fifth switch Q5 and the sixth switch Q6. This is equivalent to disconnecting the path from the second normal supply voltage KL30_1 (the supply voltage related to functional safety) to the output, putting the high-side switching circuit into a safe state. At this time, whether the first normal supply voltage KL30_0 is overvoltage or undervoltage, it will not affect the second normal supply voltage KL30_1.

[0045] After the fifth switch Q5 and the sixth switch Q6 are turned off, the direct path between the common connection point of the second terminal of the seventh switch Q7 and the second terminal of the eighth switch Q8 and the second normal supply voltage KL30_1 is broken, and the first input terminal of the turn-off latch circuit 40 is no longer energized. However, due to the interlocking of switches Q11 and Q12, the current path composed of the power supply of the turn-off latch circuit, switch Q11, and resistor R5 can still provide the base current for switch Q12 to maintain its conduction. Therefore, switch Q12 can maintain its conduction state, thereby continuously maintaining the conduction of switch Q13 and the turn-off of the fifth switch Q5 and the sixth switch Q6 (i.e., the turn-off state of the fifth switch Q5 and the sixth switch Q6 is latched), thus achieving reliable protection of the power supply of the functional safety-related controller.

[0046] When the output voltage Emergecy_feed of the backup power supply is connected, since t1 < t2, the second disable circuit 42 will first detect whether the common junction voltage of the second terminal of the third switch Q3 and the second terminal of the fourth switch Q4 of any first switch circuit is greater than the preset second voltage threshold before the first disable circuit 41 detects the output voltage of the backup power supply. If there is a double failure, then the common junction voltage of the second terminal of the third switch Q3 and the second terminal of the fourth switch Q4 of one of the first switch circuits must be greater than the preset second voltage threshold. The switch Q15 of the second disable circuit 42 will be turned on, thereby pulling down the voltage of the control terminal of the switch Q14 to ground, turning off the switch Q14, and thus disabling the first disable circuit 41. Because a double-point failure has occurred, the shutdown latch circuit 40 will also detect that the voltage at the common junction of the second terminal of the seventh switch Q7 and the second terminal of the eighth switch Q8 is greater than a preset first voltage threshold. The switch protection drive circuit 3 will then latch the fifth switch Q5 and the sixth switch Q6 into a shutdown state. This will not contradict the external switching control module's control of the fifth switch Q5 and the sixth switch Q6 of the second switching circuit after emergency power is connected. The first and second disable circuits can eliminate the impact of the safety mechanism (shutdown latch circuit) on the normal function of the circuit in the absence of a double-point failure, allowing the high-side switch control circuit to switch normally between emergency power mode and normal operation mode.

[0047] Figure 6 A circuit diagram of a protection circuit according to a second embodiment of the present invention is shown. The main difference between this second embodiment and the first embodiment is that the circuit structure of the second disable circuit 42 in the second embodiment is different from that in the first embodiment.

[0048] In this second embodiment, the second disable circuit includes the same number of second disable circuit branches as the first switching circuit. In this embodiment, there are two second disable circuit branches. Each second disable circuit branch includes a third RC filter circuit, a third voltage divider circuit, and a switching transistor Q15. The third RC filter circuit includes a resistor R12 and a capacitor C3, and the third voltage divider circuit includes a resistor R13 and a resistor R14.

[0049] The input terminals of the third RC filter circuits of the two second disable circuit branches are respectively connected to the common connection points of the second terminals of the third switch transistor Q3 and the fourth switch transistor Q4 of the two first switch circuits. The output terminal of the third RC filter circuit of each second disable circuit branch is connected to the input terminal of the third voltage divider circuit of that second disable circuit branch. The output terminal of the third voltage divider circuit is connected to the control terminal of the switch transistor Q15. The first terminal of the switch transistor Q15 is connected to the control terminal of the switch transistor Q14, and the second terminal of the switch transistor Q15 is grounded.

[0050] In this second embodiment, the switching transistor Q15 is an NPN transistor, and the base, collector, and emitter of the NPN transistor Q15 constitute the control terminal, the first terminal, and the second terminal of the switching transistor Q15, respectively.

[0051] exist Figure 5 and Figure 6 In the diagram, KL30_0_Emer1 is the common connection point of the second terminal of the third switch Q3 and the second terminal of the fourth switch Q4 in the first circuit of the first path, and KL30_0_Emer2 is the common connection point of the second terminal of the third switch Q3 and the second terminal of the fourth switch Q4 in the second circuit of the first path.

[0052] In other embodiments, the number of first switching circuits can also be one, three, four, etc. For several first switching circuits (in this application, "several circuits" means one or more circuits), the several input terminals of the second disable circuit are respectively connected to the common connection point of the second terminal of the third switch transistor Q3 and the second terminal of the fourth switch transistor Q4 of the several first switching circuits.

[0053] The high-side switch control circuit of this embodiment of the invention provides dual-point failure protection, covering both the first and second dual-point failures mentioned above. Its functionality is comprehensive, and due to real-time detection, it offers high diagnostic coverage. In the absence of a failure, the high-side switch control circuit of this embodiment of the invention will not affect the normal functions of the circuit, such as power-on startup and switching functions.

[0054] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A high-side switch control circuit with dual-point failure protection function, characterized in that, include: Backup power supply voltage input terminal, used to connect the output voltage of the backup power supply; Several first switching circuits are provided. Each first switching circuit includes a first switching transistor Q1 and a second switching transistor Q2 connected back-to-back, and a third switching transistor Q3 and a fourth switching transistor Q4 connected back-to-back. The first terminal of the first switching transistor Q1 is used to connect to a first conventional power supply voltage, and the second terminal of the first switching transistor Q1 is connected to the second terminal of the second switching transistor Q2. The first terminal of the third switching transistor Q3 is connected to the backup power supply voltage input terminal, and the second terminal of the third switching transistor Q3 is connected to the second terminal of the fourth switching transistor Q4. The first terminal of the fourth switching transistor Q4 and the first terminal of the second switching transistor Q2 are both connected to a first common node P1, and the first common node P1 serves as the output terminal of the first switching circuit. The second switching circuit includes a fifth switch Q5 and a sixth switch Q6 connected back-to-back, and a seventh switch Q7 and an eighth switch Q8 connected back-to-back. The first terminal of the fifth switch Q5 is used to connect to the second conventional power supply voltage, and the second terminal of the fifth switch Q5 is connected to the second terminal of the sixth switch Q6. The first terminal of the seventh switch Q7 is connected to the backup power supply voltage input terminal, and the second terminal of the seventh switch Q7 is connected to the second terminal of the eighth switch Q8. The first terminals of the eighth switch Q8 and the sixth switch Q6 are both connected to the second common node P2, and the second common node P2 serves as the output terminal of the second switching circuit. A switching transistor protection drive circuit, wherein the output terminal of the switching transistor protection drive circuit is connected to the control terminal of the fifth switching transistor Q5 and the control terminal of the sixth switching transistor Q6, respectively. The protection circuit has its first input terminal connected to the common junction of the second terminals of the seventh switch Q7 and the eighth switch Q8. Several second input terminals of the protection circuit are respectively connected to the common junctions of the second terminals of the third switch Q3 and the fourth switch Q4 of several first switch circuits. The third input terminal of the protection circuit is connected to the backup power supply voltage input terminal. The output terminal of the protection circuit is connected to the input terminal of the switch protection drive circuit. The protection circuit is used to latch the fifth switch Q5 and the sixth switch Q6 into a turned-off state through the switch protection drive circuit when the voltage at the common junction of the second terminals of the seventh switch Q7 and the eighth switch Q8 is greater than a preset first voltage threshold, and the voltage at the common junction of the second terminals of the third switch Q3 and the fourth switch Q4 of any first switch circuit is greater than a preset second voltage threshold.

2. The high-side switch control circuit with dual-point failure protection function according to claim 1, characterized in that, The protection circuit includes a shutdown latch circuit, a first disable circuit, and a second disable circuit. The first input terminal of the shutdown latch circuit is connected to the common junction of the second terminal of the seventh switch Q7 and the second terminal of the eighth switch Q8. The output terminal of the shutdown latch circuit is connected to the input terminal of the switch protection drive circuit. The shutdown latch circuit is used to latch the fifth switch Q5 and the sixth switch Q6 into the shutdown state through the switch protection drive circuit when the voltage at the common junction of the second terminal of the seventh switch Q7 and the second terminal of the eighth switch Q8 is detected to be greater than a preset first voltage threshold. The first input terminal of the first disable circuit is connected to the backup power supply voltage input terminal, and the output terminal of the first disable circuit is connected to the second input terminal of the shutdown latch circuit. The first disable circuit is used to disable the shutdown latch circuit when the output voltage of the backup power supply is detected. The input terminals of the second disable circuit are respectively connected to the common junction of the second terminals of the third switch transistor Q3 and the second terminals of the fourth switch transistor Q4 of the first switch circuit. The output terminal of the second disable circuit is connected to the second input terminal of the first disable circuit. The second disable circuit is used to disable the first disable circuit when the voltage at the common junction of the second terminals of the third switch transistor Q3 and the second terminals of the fourth switch transistor Q4 of any first switch circuit is greater than a preset second voltage threshold. Wherein, t1 < t2 < t3, t1 is the time taken for the second disable circuit to detect that the common contact voltage of the second terminal of the third switch Q3 and the second terminal of the fourth switch Q4 in any one of the first switch circuits is greater than the preset second voltage threshold, t2 is the time taken for the first disable circuit to detect that the output voltage of the backup power supply is connected, and t3 is the time taken for the shutdown latch circuit to detect that the common contact voltage of the second terminal of the seventh switch Q7 and the second terminal of the eighth switch Q8 is greater than the preset first voltage threshold.

3. The high-side switch control circuit with dual-point failure protection function according to claim 2, characterized in that, The shutdown latch circuit includes a first voltage divider circuit, a first RC filter circuit, a switching transistor Q11, a switching transistor Q12, and a switching transistor Q13; The input terminal of the first RC filter circuit is connected to the first input terminal of the shutdown latch circuit, and the output terminal of the first RC filter circuit is connected to the input terminal of the first voltage divider circuit. The output terminal of the first voltage divider circuit is connected to the control terminal of the switching transistor Q12, the first terminal of the switching transistor Q12 is connected to the control terminal of the switching transistor Q11, and the second terminal of the switching transistor Q12 is grounded. The first terminal of the switching transistor Q11 is connected to the control terminal of the switching transistor Q13, and the second terminal of the switching transistor Q11 is connected to the power supply of the shutdown latch circuit. The first terminal of the switching transistor Q13 serves as the output terminal of the shutdown latch circuit, and the second terminal of the switching transistor Q13 is grounded.

4. The high-side switch control circuit with dual-point failure protection function according to claim 3, characterized in that, The switching transistor Q12 is an NPN transistor, and the base, collector, and emitter of the NPN transistor Q12 constitute the control terminal, the first terminal, and the second terminal of the switching transistor Q12, respectively; the switching transistor Q11 is a PNP transistor, and the base, collector, and emitter of the PNP transistor Q11 constitute the control terminal, the first terminal, and the second terminal of the switching transistor Q11, respectively. The shutdown latch circuit includes resistors R3, R5, and R6; one end of resistor R3 is connected to the control terminal of switch Q12 and the output terminal of the first voltage divider circuit, and the other end of resistor R3 is connected to the first terminal of switch Q11; one end of resistor R5 is connected to the power supply of the shutdown latch circuit and the second terminal of switch Q11, and the common connection point of the other end of resistor R5 and one end of resistor R6 is connected to the control terminal of switch Q11, and the other end of resistor R6 is connected to the first terminal of switch Q12.

5. The high-side switch control circuit with dual-point failure protection function according to claim 4, characterized in that, The switching transistor Q13 is an NMOS transistor, and the gate, drain, and source of the NMOS transistor constitute the control terminal, the first terminal, and the second terminal of the switching transistor Q13, respectively. The shutdown latch circuit includes resistors R7 and R8; one end of resistor R7 is connected to the common connection point of the other end of resistor R3 and the first end of switching transistor Q11, the common connection point of the other end of resistor R7 and one end of resistor R8 is connected to the control terminal of switching transistor Q13, and the other end of resistor R8 is grounded.

6. The high-side switch control circuit with dual-point failure protection function according to claim 3 or 4, characterized in that, The power supply for the shutdown latch circuit is the second conventional output voltage.

7. The high-side switch control circuit with dual-point failure protection function according to claim 3, characterized in that, The first power-disabled circuit includes a second RC filter circuit, a second voltage divider circuit, and a switching transistor Q14; The input terminal of the second RC filter circuit is connected to the backup power supply voltage input terminal, the output terminal of the second RC filter circuit is connected to the input terminal of the second voltage divider circuit, the output terminal of the second voltage divider circuit is connected to the control terminal of the switching transistor Q14, the first terminal of the switching transistor Q14 is connected to the control terminal of the switching transistor Q12, and the second terminal of the switching transistor Q14 is grounded. The time constant of the second RC filter circuit is less than the time constant of the first RC filter circuit.

8. The high-side switch control circuit with dual-point failure protection function according to claim 7, characterized in that, The second power-disabling circuit includes a number of diodes D1, a third RC filter circuit, a third voltage divider circuit, and a switching transistor Q15, which are the same number as those in the first switching circuit. The anodes of the plurality of diodes D1 are respectively connected to the common junction of the second terminals of the third switching transistors Q3 and Q4 of the plurality of first switching circuits. The common junction of the cathodes of the plurality of diodes D1 is connected to the input terminal of the third RC filter circuit. The output terminal of the third RC filter circuit is connected to the input terminal of the third voltage divider circuit. The output terminal of the third voltage divider circuit is connected to the control terminal of the switching transistor Q15. The first terminal of the switching transistor Q15 is connected to the control terminal of the switching transistor Q14, and the second terminal of the switching transistor Q15 is grounded. The time constant of the third RC filter circuit is less than the time constant of the second RC filter circuit.

9. The high-side switch control circuit with dual-point failure protection function according to claim 7, characterized in that, The second power-disabling circuit includes a number of second power-disabling circuit branches, the same as the number of first switching circuits. Each second power-disabling circuit branch includes a third RC filter circuit, a third voltage divider circuit, and a switching transistor Q15. The input terminals of the third RC filter circuits of several second disable circuit branches are respectively connected to the common connection points of the second terminals of the third switch transistors Q3 and Q4 of several first switch circuits. The output terminal of the third RC filter circuit of each second disable circuit branch is connected to the input terminal of the third voltage divider circuit of that second disable circuit branch. The output terminal of the third voltage divider circuit of each second disable circuit branch is connected to the control terminal of switch transistor Q15. The first terminal of switch transistor Q15 is connected to the control terminal of switch transistor Q14, and the second terminal of switch transistor Q15 is grounded. The time constant of the third RC filter circuit is less than the time constant of the second RC filter circuit.

10. The high-side switch control circuit with dual-point failure protection function according to claim 1, characterized in that, The first switch Q1 to the eighth switch Q8 are all NMOS transistors. The gate, drain and source of the NMOS transistor constitute the control terminal, the first terminal and the second terminal of the switch, respectively.

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