A low-voltage power supply processing circuit and a power-on and power-off control method

Abstract

The present invention discloses a low-voltage power supply processing circuit and a power-on / off control method. It includes a power-on / off control module, a power supply protection module, and a wake-up source detection module. The power-on / off control module includes a first input module, a second input module, a wake-up holding module, and a switch on / off module. The switch on / off module is used to output a power supply voltage to the power supply protection module when receiving a high-level wake-up signal. The power supply protection module includes a surge suppressor U1 and a MOS protection circuit. The surge suppressor U1 is used to control the on / off of the MOS protection circuit. The wake-up holding module is used to judge the type of the wake-up source according to the received detection result. The power-on / off control module of the present invention judges the on / off of the power supply through two wake-up sources, not limited to only one wake-up source, and has strong versatility. When the wake-up source is invalid, the power supply of the power supply protection module is disconnected, no current flows in the circuit, and the static current is close to zero, effectively reducing the consumption of the static current.

Description

Technical Field

[0001] The present invention belongs to the technical field of automotive electronics, and particularly relates to a low-voltage power supply processing circuit and a power-on and power-off control method. Background Art

[0002] The low-voltage DC power supply of the on-vehicle power supply system of passenger cars is generally 12V, but there may be various abnormal conditions on the power supply, such as overvoltage, overcurrent, load dump, voltage reversal, etc. It is required that in-vehicle electronic components can protect the circuit from damage and even work normally when the power supply is abnormal. For low-voltage power supply abnormal conditions, traditional methods are based on multiple discrete components for protection. For example, a transient voltage suppressor (TVS) is used to provide overvoltage protection, a line fuse is used to provide overcurrent protection, a series diode is used to provide reverse protection, etc. However, the TVS tube is easily burned out when the overvoltage time is slightly longer; once the fuse is burned out, it must be replaced, and the maintenance is complex; the diode anti-reverse reduces the voltage reaching the circuit, and the diode itself has a large power consumption and is easily damaged; using discrete components, the parameter selection is complex, and if current detection is to be realized, the circuit design is complex. Summary of the Invention

[0003] The purpose of the present invention is to solve the deficiencies existing in the above background art, and provide a low-voltage power supply processing circuit and a power-on and power-off control method.

[0004] The technical solution adopted by the present invention is: a low-voltage power supply processing circuit includes a power-on and power-off control module, a power supply protection module, and a wake-up source detection module.

[0005] The power-on and power-off control module includes a first input module, a second input module, a wake-up holding module, and a switch on-off module. The first input module is used to connect to a first wake-up source, the second input module is used to connect to a second wake-up source. The output ends of the first input module, the second input module, and the wake-up holding module are all connected to the input end of the switch on-off module. The switch on-off module is used to output a power supply voltage to the power supply protection module when receiving a high-level wake-up signal.

[0006] The power supply protection module includes a surge suppressor U1 and a MOS protection circuit. One end of the MOS protection circuit is connected to the power supply, and the other end is connected to a low-voltage load. The surge suppressor U1 is used to control the on-off of the MOS protection circuit.

[0007] The wake-up source detection module is used to detect the first wake-up source and the second wake-up source, and send the detection result to the wake-up holding module. The wake-up holding module is used to judge the type of the wake-up source according to the received detection result and store program key parameters when the wake-up source is invalid.

[0008] Furthermore, the first wake-up source is an ignition signal.

[0009] Further, the second wake-up source is a communication wake-up signal sent by any one of the CAN bus, LIN bus, and Ethernet bus.

[0010] Further, the first input module includes a resistor R1 and a diode D1. One end of the resistor R1 is connected to the first wake-up source, and the other end is connected to the anode of the diode D1. The cathode of the diode D1 is connected to the input end of the switch on / off module.

[0011] Further, the second input module includes a communication module U3, a resistor R2, and a diode D2. The input end of the communication module U3 is connected to the second wake-up source, and the output end is connected to one end of the resistor R2. The other end of the resistor R2 is connected to the anode of the diode D1. The cathode of the diode D1 is connected to the input end of the switch on / off module.

[0012] Further, the wake-up holding module includes a main control module U2, a resistor R3, and a diode D3. The input end of the main control module U2 is connected to the output end of the wake-up source detection module. The output end of the main control module U2 is connected to one end of the resistor R3. The other end of the resistor R3 is connected to the anode of the diode D3. The cathode of the diode D3 is connected to the input end of the switch on / off module.

[0013] Further, the switch on / off module includes a triode Q1, a triode Q2, resistors R4, R5, R6, R7, a capacitor C1, and a zener diode ZD1. The base of the triode Q1 is connected to the output ends of the first input module and the second input module and one end of the resistor R4. The emitter of the triode Q1 is grounded. The collector of the triode Q1 is connected to one end of the resistor R6. The other end of the resistor R6 is connected to one end of the resistor R5 and the base of the triode Q2. The other end of the resistor R5 is connected to the power supply. The other end of the resistor R4 is grounded. The emitter of the triode Q2 is connected to the power supply. The collector of the triode Q2 is connected to one end of the resistor R7. The other end of the resistor R7 is connected to the power supply end of the power supply protection module, one end of the capacitor C1, and the cathode of the zener diode ZD1. The other end of the capacitor C1 and the anode of the zener diode ZD1 are grounded.

[0014] Further, the MOS protection circuit includes MOS transistors Q3, Q4, resistors R8, R9, R10, R11, resistor RSN, and capacitor C3. The drain of the MOS transistor Q3 is connected to the power supply. The source of the MOS transistor Q3 is connected to the source of the MOS transistor Q4. The drain of the MOS transistor Q4 is connected to the low-voltage load through the resistor RSN. The gates of the MOS transistor Q3 and the MOS transistor Q4 are respectively connected to the GATE pin of the surge suppressor U1 through the resistors R9 and R10. The GATE pin of the surge suppressor U1 is also grounded through the series-connected resistors R11 and capacitor C3. One end of the resistor R8 is connected to the power supply, and the other end is connected to the DRN pin of the surge suppressor U1.

[0015] Further, the wake-up source detection module includes a resistor R12, a resistor R13, a resistor R14, a resistor R15, a voltage regulator diode ZD2, and a voltage regulator diode ZD3. One end of the resistor R12 is connected to the first wake-up source, and the other end is connected to one end of the resistor R13 and the input end of the wake-up holding module. The other end of the resistor R13 is grounded, and the voltage regulator diode ZD2 is connected in parallel with the resistor R13; one end of the resistor R14 is connected to the second wake-up source, and the other end is connected to one end of the resistor R15 and the input end of the wake-up holding module. The other end of the resistor R15 is grounded, and the voltage regulator diode ZD3 is connected in parallel with the resistor R15.

[0016] A power-on and power-off control method for a low-voltage power supply processing circuit based on the above, determines whether the wake-up source is valid. If it is valid, the power supply is maintained and the power-on is completed; during the power supply process, it is continuously detected whether the wake-up source is invalid. If it is invalid, the wake-up holding module delays the power-off and starts to store the key parameters of the program until the power supply is cut off after the key parameters of the program are stored. The specific steps are as follows:

[0017] Step 1: Power-on wake-up. There are two ways to power-on wake-up. Way 1 is to wake up through the ignition signal, and way 2 is to wake up through the communication module.

[0018] Way 1 works as follows: Before the vehicle is ignited, the signals ING, Comm_Awake, and MCU_ON have no signal output, and the circuit does not work; after the vehicle is ignited, the ignition signal IGN outputs a high level. After passing through the resistor R1 and the diode D1 and being divided by the resistor R4, the triode Q1 is turned on. After being divided by the resistors R5 and R6, the triode Q2 is turned on. The conduction of the triode Q2 supplies power to the surge suppressor LTC4380 through the resistor R7 and enables the ON pin of the chip. Furthermore, the voltage of the GATE pin rises, causing the MOS transistors Q3 and Q4 to conduct and the Vout voltage to be established, and the power-on startup is completed.

[0019] Way 2 works as follows: In the state of no ignition signal, if there is a message on the communication harness, the communication module U3 is woken up, and it outputs a communication wake-up signal Comm_Awake. Furthermore, the triode Q1 is turned on and the Vout voltage is established, and the power-on startup is completed.

[0020] Step 2: After the Vout voltage is established, the program of the main control module U2 runs, and the output signal MCU_ON is at a high level. After passing through the resistor R3 and the diode D3, the triode Q1 is kept in a conducting state to ensure that the circuit continues to work when the ignition signal is abnormal (such as being interfered) or when the communication wake-up signal Comm_Awake disappears. The communication wake-up signal Comm_Awake can be sent by communications such as CAN, LIN, Ethernet, etc.

[0021] Step 3: The main control module U2 detects the status of the ignition signal in real time through the wake-up source detection module. When it is found that the ignition signal is an invalid low level, or when it learns through the message of the communication module U3 that the circuit is no longer required to work, the main control module U2 still keeps MCU_ON at a high level (a function of U2 itself), ensuring that the circuit can work normally, and starts to store key parameters and information into the memory. After the storage is completed, it controls MCU_ON to output a low level, then the triode Q1 disconnects, and the power-down is completed.

[0022] The beneficial effects of the present invention are as follows:

[0023] The power-on and power-off control module of the present invention judges the on-off of power supply through two wake-up sources to meet the requirements of different vehicle working conditions, not limited to only one wake-up source, and has strong versatility; when the wake-up source is invalid, the power supply protection module disconnects the power supply, and there is no current flowing in the circuit, and the static current is close to zero, effectively reducing the consumption of static current; the wake-up source detection module sends the detected wake-up source to the wake-up holding module, and the wake-up holding module can know which specific wake-up source it is according to the received signal, providing a basis for other controls of the vehicle, and can also delay the power-down when the wake-up source is invalid to save the key parameters and information of the circuit in time; the power supply protection module adopts a surge buffer combined with a MOS protection circuit, which can make the output voltage start softly and reduce the starting surge current.

[0024] The power supply protection module of the present invention consists of a surge suppressor U1, two back-to-back NMOS transistors, and several resistors and capacitors, which simply and reliably realizes the protection against overvoltage, overcurrent, reverse voltage, etc. of the input power supply Vin, making the output power supply Vout a stable limited voltage, or cutting off the output of Vout, thus protecting the subsequent circuit. Description of the Drawings

[0025] Figure 1 is the circuit schematic diagram of the present invention.

[0026] Figure 2 is the control flow chart of the present invention. Detailed Embodiments

[0027] The following further describes the detailed embodiments of the present invention with reference to the drawings. It should be noted here that the description of these embodiments is for helping to understand the present invention, but does not constitute a limitation to the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] Such as Figure 1As shown in the figure, the present invention provides a low-voltage power supply processing circuit, which includes a power-on and power-off control module 10, a power supply protection module 20, and a wake-up source detection module 30. The power-on and power-off control module 10 has two wake-up sources: an ignition signal and a communication wake-up. When the wake-up source is at a high level, the low-voltage input Vin supplies power to the power supply protection module 20 to turn it on; the power supply protection module 20 is composed of a surge suppressor, back-to-back NMOS transistors, and resistors and capacitors. When there are situations such as overvoltage, overcurrent, and reverse voltage in the input power supply Vin, the circuit plays a protective role and does not damage other components after the circuit output Vout. The wake-up source detection module 30 detects the levels of the two wake-up sources respectively by the main control module to determine the wake-up source.

[0029] Specifically, the power-on and power-off control module includes a first input module, a second input module, a wake-up holding module, and a switch on-off module. The first input module is used to connect to the first wake-up source, the second input module is used to connect to the second wake-up source. The output ends of the first input module, the second input module, and the wake-up holding module are all connected to the input end of the switch on-off module. The switch on-off module is used to output a power supply voltage to the power supply protection module when receiving a high-level wake-up signal.

[0030] The power supply protection module includes a surge suppressor U1 and a MOS protection circuit. One end of the MOS protection circuit is connected to the power supply, and the other end is connected to the low-voltage load. The surge suppressor U1 is used to control the on-off of the MOS protection circuit.

[0031] The wake-up source detection module is used to detect the first wake-up source and the second wake-up source, and send the detection result to the wake-up holding module. The wake-up holding module is used to judge the type of the wake-up source according to the received detection result and store the program key parameters when the wake-up source is invalid.

[0032] The working principle of the low-voltage power supply processing circuit of the present invention is as follows:

[0033] The input ignition signal IGN is connected to R4 after being serially connected with resistor R1 and diode D1. The communication wake-up signal Comm_Awake is connected to R4 after being serially connected with resistor R2 and diode D2. The main control module control signal MCU_ON is connected to resistor R4 after being serially connected with resistor R3 and diode D3. Among them, resistor R1, resistor R2, and resistor R3 respectively form voltage dividers with resistor R4, while diodes D1, D2, and D3 isolate the signal levels, avoiding the mutual influence of the ignition signal IGN, the communication wake-up signal Comm_Awake, and the control signal MCU_ON. Both ends of resistor R4 are respectively connected to the B and E poles of NPN transistor Q1, where the E pole is grounded to GND. The C pole of transistor Q1 is connected to resistor R6, and resistor R6 is serially connected with resistor R5 and then connected to Vin. Both ends of resistor R5 are also connected to the E and B poles of PNP transistor Q2, where the E pole is connected to Vin. The C pole of transistor Q2 is connected to resistor R7, and resistor R7 is serially connected with capacitor C1 and then grounded to GND. Zener diode ZD1 is connected in parallel with capacitor C1. When either the ignition signal IGN or the communication wake-up signal Comm_Awake is at a high level, it can turn on NPN transistor Q1, so that resistor R5 and resistor R6 form a voltage divider, then PNP transistor Q2 is turned on, and after passing through resistor R7, it supplies power to the surge suppressor U1.

[0034] The surge suppressor U1 is the chip LTC4380-2. One end of the resistor R8 is connected to Vin, and the other end is connected to the DRN pin of the surge suppressor U1. There are two NMOS transistors Q3 and Q4. The D pole of the MOS transistor Q3 is connected to Vin, the S pole is connected to the S pole of the MOS transistor Q4, and the G pole is connected to the resistor R9. The other end of the resistor R9 is respectively connected to the resistor R10, the resistor R11, and the GATE pin of the surge suppressor U1. The G pole of the MOS transistor Q4 is connected to R10, and the D pole is connected to the resistor RSN and the SNS pin of the surge suppressor U1. The other end of RSN is connected to Vout and the OUT pin of the surge suppressor U1. The other end of the resistor R11 is connected in series with the capacitor C3. The other end of the capacitor C3 is grounded to GND. One end of the capacitor C2 is connected to the TMR pin of the surge suppressor U1, and the other end is grounded to GND. The GND and SEL pins of the surge suppressor U1 are grounded to GND. After the power input pin VCC and the power-on control pin ON of the surge suppressor U1 are powered on, the chip starts to work. The voltage of its GATE pin rises, making the NMOS transistors Q3 and Q4 fully conductive, so that Vout is powered on. During the rising process of the voltage of the GATE pin, the capacitor C3 is charged through the resistor R11, slowing down the voltage rising rate, thus avoiding a large surge starting current. The resistors R9 and R10 use resistors with a small resistance value, such as 10Ω, to suppress the parasitic oscillation of the MOS transistor. The SEL pin of the surge suppressor U1 is connected to GND, setting the internal clamping voltage of the LTC4380-2 to 31.5V. When overvoltage or surge voltage appears in Vin, the voltage of Vout can be limited below 27V. The resistor R7 and the capacitor C1 form a filter circuit to filter out spikes and transient high voltages. If the voltage is too high, the zener diode ZD1 conducts to protect the surge suppressor U1. When the output is short-circuited or overcurrent occurs, the surge suppressor U1 adjusts the voltage of the GATE pin by detecting the voltage across the resistor RSN to limit the current flowing through RSN. The voltage of the DRN pin of the surge suppressor U1 tracks the OUT pin, generating a DRN pin current flowing through the external resistor R8 that is proportional to the Vds voltage of the external MOS transistor. The DRN pin current is multiplied internally by the voltage ΔVSNS across the current sensing resistor RSN (i.e., Vsns–Vout) to generate a TMR pin current approximately proportional to the power dissipation of the MOSFET. The TMR pin is connected to the capacitor C2 to set the fault shutdown time and the cooling cycle. After overvoltage protection and overcurrent protection occur, the surge suppressor U1 chip has an automatic restart function, and the circuit can automatically restart after the fault disappears. When the positive and negative poles of the input voltage power supply Vin are reversed, both the triode Q1 and the triode Q2 are cut off. The zener diode ZD1 protects the VCC and ON pins of the surge suppressor U1, and the back-to-back MOS transistors Q3 and Q4 prevent the reverse voltage from conducting.

[0035] One end of the resistor R12 is connected to the ignition signal IGN, and the other end is connected in series with the resistor R13 to divide the voltage of the ignition signal. The voltage division point is connected to the main control module U2. The voltage stabilizing diode ZD2 is connected in parallel with the resistor R13. One end of the resistor R14 is connected to the communication wake-up signal Comm_Awake, and the other end is connected in series with the resistor R15 to divide the voltage of the communication wake-up signal. The voltage division point is connected to the main control module U2. The voltage stabilizing diode ZD3 is connected in parallel with the resistor R15. The other ends of the resistors R13 and R15 are grounded. The main control module U2 detects the high and low levels of the voltage division point in real time to determine the current wake-up source.

[0036] Based on the above low-voltage power supply processing circuit, the present invention also provides a power-on and power-off control method, as Figure 2 shown, the process is as follows:

[0037] The wake-up sources are the ignition signal or the communication wake-up signal respectively. The two signals are combined into a wake-up source through a diode in the circuit. First, in step S101, it is judged whether the wake-up source is valid (high level is valid). If it is invalid, the power is not turned on. If it is valid, step S102 is entered. The circuit is powered on and the main control module outputs MCU_ON as high level to maintain the power supply, and the power-on is completed. During operation, the main control module detects the wake-up source in real time and enters step S103 to judge whether the wake-up source is invalid (low level is invalid). If the wake-up source is invalid, step S104 is entered for delayed power-off. The main control module stores information. The main information stored during the delayed power-off is the key parameters during the operation of this program, such as the fault parameters that occurred during this work. Some products have a self-learning function and can store the parameters after self-learning. The stored key parameters are used after the product is powered on again, such as troubleshooting according to the fault parameters, or using the learned parameters according to the working condition changes to make the product run more reliably. Then step S105 is entered. If the information storage is not completed, continue to store. If the information storage is completed, step S106 is entered, and the main control module outputs MCU_ON as low level to cut off the power supply.

[0038] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art.

Claims

1. A low-voltage power supply processing circuit, characterized in that: It includes a power-on / off control module, a power supply protection module, and a wake-up source detection module. The power-on / off control module includes a first input module, a second input module, a wake-up hold module, and a switch on / off module. The first input module is used to connect to a first wake-up source, and the second input module is used to connect to a second wake-up source. The output ends of the first input module, the second input module, and the wake-up hold module are all connected to the input end of the switch on / off module. The switch on / off module is used to output a power supply voltage to the power supply protection module when receiving a high-level wake-up signal. The power supply protection module includes a surge suppressor U1 and a MOS protection circuit. One end of the MOS protection circuit is connected to the power supply, and the other end is connected to a low-voltage load. The surge suppressor U1 is used to control the on / off of the MOS protection circuit. The wake-up source detection module is used to detect the first wake-up source and the second wake-up source, and send the detection result to the wake-up hold module. The wake-up hold module is used to judge the type of the wake-up source according to the received detection result and store the program key parameters when the wake-up source is invalid. The switch on / off module includes a triode Q1, a triode Q2, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C1, and a zener diode ZD1. The base of the triode Q1 is connected to the output ends of the first input module and the second input module and one end of the resistor R4. The emitter of the triode Q1 is grounded, and the collector of the triode Q1 is connected to one end of the resistor R6. The other end of the resistor R6 is connected to one end of the resistor R5 and the base of the triode Q2. The other end of the resistor R5 is connected to the power supply, and the other end of the resistor R4 is grounded. The emitter of the triode Q2 is connected to the power supply, and the collector is connected to one end of the resistor R7. The other end of the resistor R7 is connected to the power supply end of the power supply protection module, one end of the capacitor C1, and the cathode of the zener diode ZD1. The other end of the capacitor C1 and the anode of the zener diode ZD1 are grounded.

2. The low-voltage power supply processing circuit according to claim 1, wherein: The first wake-up source is an ignition signal.

3. The low-voltage power supply processing circuit according to claim 1, wherein: The second wake-up source is a communication wake-up signal sent by any one of the CAN bus, LIN bus, and Ethernet bus.

4. The low-voltage power supply processing circuit according to claim 1, wherein: The first input module includes a resistor R1 and a diode D1. One end of the resistor R1 is connected to the first wake-up source, and the other end is connected to the anode of the diode D1. The cathode of the diode D1 is connected to the input end of the switch on / off module.

5. The low-voltage power supply processing circuit according to claim 1, characterized in that: The second input module includes a communication module U3, a resistor R2, and a diode D2. The input end of the communication module U3 is connected to the second wake-up source, and the output end is connected to one end of the resistor R2. The other end of the resistor R2 is connected to the anode of the diode D1. The cathode of the diode D1 is connected to the input end of the switch on / off module.

6. The low-voltage power supply processing circuit according to claim 1, characterized in that: The wake-up hold module includes a main control module U2, a resistor R3, and a diode D3. The input end of the main control module U2 is connected to the output end of the wake-up source detection module. The output end of the main control module U2 is connected to one end of the resistor R3. The other end of the resistor R3 is connected to the anode of the diode D3. The cathode of the diode D3 is connected to the input end of the switch on / off module.

7. The low-voltage power supply processing circuit according to claim 1, wherein: The MOS protection circuit includes MOS transistor Q3, MOS transistor Q4, resistor R8, resistor R9, resistor R10, resistor R11, resistor RSN and capacitor C3. The drain of MOS transistor Q3 is connected to the power supply, and the source is connected to the source of MOS transistor Q4. The drain of MOS transistor Q4 is connected to the low-voltage load through resistor RSN. The gates of MOS transistor Q3 and MOS transistor Q4 are respectively connected to the GATE pin of surge suppressor U1 through resistor R9 and resistor R10. The GATE pin of surge suppressor U1 is also grounded through the series-connected resistor R11 and capacitor C3. One end of resistor R8 is connected to the power supply, and the other end is connected to the DRN pin of surge suppressor U1.

8. The low-voltage power supply processing circuit according to claim 1, wherein: The wake-up source detection module includes resistor R12, resistor R13, resistor R14, resistor R15, zener diode ZD2 and zener diode ZD3. One end of resistor R12 is connected to the first wake-up source, and the other end is connected to one end of resistor R13 and the input end of the wake-up hold module. The other end of resistor R13 is grounded, and zener diode ZD2 is connected in parallel with resistor R13. One end of resistor R14 is connected to the second wake-up source, and the other end is connected to one end of resistor R15 and the input end of the wake-up hold module. The other end of resistor R15 is grounded, and zener diode ZD3 is connected in parallel with resistor R15.

9. A power-on and power-off control method for a low-voltage power supply processing circuit according to claim 1, characterized in that: Judge whether the wake-up source is valid. If it is valid, keep the power supply and the power-on is completed. During the power supply process, continuously detect whether the wake-up source is invalid. If it is invalid, the wake-up hold module delays power-off and starts to store the key parameters of the program until the key parameters of the program are stored and then the power supply is cut off.

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