Power supply detection and protection circuit for vehicle-mounted electronic equipment

Abstract

The utility model provides a power supply detection and protection circuit for vehicle-mounted electronic equipment. The power supply detection and protection circuit comprises a trunk line circuit, a voltage regulation and control circuit, a high-low voltage interruption detection circuit and a voltage sampling circuit, the power supply end of the trunk line circuit is connected with a power supply, the input end of the trunk line circuit is connected with a switching signal of the MCU, and the first output end of the trunk line circuit is connected with the voltage regulation and control circuit, the high-low voltage interruption detection circuit and the voltage sampling circuit; the other output end of the trunk line circuit is connected with the power supply end of the vehicle-mounted electronic equipment; the output end of the voltage regulation and control circuit is respectively connected with the power supply end of the MCU, the high-low voltage interruption detection circuit and the voltage sampling circuit; the output ends of the high and low voltage interruption detection circuit and the voltage sampling circuit are respectively connected to the first and second signal input ends of the MCU; according to the utility model, systematic quantitative input protection can be realized, and meanwhile, the detection precision and the response rate can be multiplied, so that countermeasures can be taken quickly.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic circuits, and more specifically to a power supply detection and protection circuit for vehicle-mounted electronic equipment. Background Art

[0002] As current automobile manufacturing technology matures, vehicle manufacturers are increasingly strict with the quality control of parts. For electronic equipment assembly parts, they are required not only to work properly, but also to be able to independently manage and control their own power supply to ensure working safety.

[0003] In-vehicle electronic devices generally implement voltage monitoring and overvoltage protection based on microcontroller units (MCUs). MCUs monitor the input voltage range in real time by collecting analog signals. Once the abnormal voltage exceeds the design requirements, the MCU outputs high and low level logic control sequences through the corresponding output ports and controls the output of the main line of the electronic device, thereby protecting the subsequent components. The current solution for power protection using MCU chips has average detection accuracy and is not responsive enough.

[0004] An existing patent document discloses a reverse connection and overvoltage protection circuit, which performs reverse connection protection and switch control by adding a MOS tube to the negative line of the ground terminal; another patent document discloses a power input protection circuit, which uses the on-off ability of the MOS to control polarity; although the above schemes can achieve reverse connection and overvoltage protection of the power supply, they cannot achieve systematic quantitative input protection, and the detection accuracy is low. Utility Model Content

[0005] One of the purposes of the utility model is to provide a vehicle-mounted electronic equipment power supply detection and protection circuit to solve the defects of the prior art that the solutions cannot achieve systematic quantitative input protection and have low detection accuracy.

[0006] In order to solve the above technical problems, the technical solution of the utility model is as follows:

[0007] A vehicle-mounted electronic device power supply detection and protection circuit is arranged between a power supply and a micro control unit MCU, wherein a control signal output terminal of the micro control unit MCU is connected to a control terminal of the vehicle-mounted electronic device, and comprises: a trunk line circuit, a voltage regulation circuit, a high and low voltage interruption detection circuit and a voltage sampling circuit;

[0008] The power supply end of the main line circuit is connected to the power supply, the input end of the main line circuit is connected to the switch signal output end of the micro control unit MCU, the first output end of the main line circuit is respectively connected to the input end of the voltage regulation circuit, the first input end of the high and low voltage interruption detection circuit, and the first input end of the voltage sampling circuit; the second output end of the main line circuit is connected to the power supply end of the vehicle-mounted electronic device;

[0009] The output end of the voltage control circuit is respectively connected to the power supply end of the micro control unit MCU, the second input end of the high and low voltage interrupt detection circuit, and the second input end of the voltage sampling circuit;

[0010] The output ends of the high and low voltage interrupt detection circuit and the voltage sampling circuit are respectively connected to the first and second signal input ends of the micro control unit MCU.

[0011] Preferably, the main line circuit comprises: a bipolar transient suppression diode D1, a power diode D2, a resistor R1, a resistor R2, an NPN transistor Q1 and a PMOS transistor Q2;

[0012] One end of the bipolar transient suppression diode D1 is connected to a power supply and serves as a power supply end of the main line circuit; the other end of the bipolar transient suppression diode D1 is grounded;

[0013] The anode of the power diode D2 is connected to a power supply, and the cathode of the power diode D2 serves as a first output terminal of the main line circuit and outputs a voltage VBAT_IN;

[0014] The first output end of the main line circuit is also connected to one end of the resistor R2 and the source of the PMOS tube Q2 respectively; the other end of the resistor R2 is connected to one end of the resistor R1 and the gate of the PMOS tube Q2 respectively; the drain of the PMOS tube Q2 serves as the second output end of the main line circuit and outputs the voltage VBAT_OUT;

[0015] The other end of the resistor R1 is connected to the collector of the NPN transistor Q1, the emitter of the NPN transistor Q1 is grounded, and the base of the NPN transistor Q1 is connected to the switch signal output end of the micro control unit MCU as the input end of the main line circuit;

[0016] The main line circuit is the main line of the entire protection circuit. The input is an external DC power supply. After being anti-electromagnetic interference and anti-reverse connection, the external DC power is used as the output of the first output terminal, and after passing through the main main switch Q2, it is used as the output of the second output terminal. The output voltage of the second output terminal powers the display screen behind.

[0017] Preferably, the main line circuit further includes: an inductor L1, an inductor L2, a capacitor C1, a capacitor C2 and a capacitor C3;

[0018] One end of the inductor L1 is connected to the cathode of the power diode D2, and the other end of the inductor L1 serves as the first output end of the main line circuit;

[0019] The other end of the inductor L1 is also connected to one end of the capacitor C1 and one end of the capacitor C2 respectively, and the other end of the capacitor C1 and the other end of the capacitor C2 are both grounded;

[0020] One end of the inductor L2 is connected to the drain of the PMOS tube Q2 and one end of the capacitor C3 respectively, and the other end of the inductor L2 serves as the second output end of the main line circuit;

[0021] The other end of the capacitor C3 is grounded;

[0022] This part is the filtering component of the main line circuit, used to filter the input and output of the main line circuit.

[0023] Preferably, the voltage control circuit controls the voltage of the first output end of the main line circuit through the power chip U1;

[0024] The power chip U1 includes any one of a DCDC chip and a LDO chip.

[0025] Preferably, the voltage control circuit comprises: an LDO chip, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, an inductor L3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7 and a capacitor C8;

[0026] The LDO chip includes: an IN pin, an OUT pin, an EN pin, a RESET pin, an ADJ pin, a TO pin, an NC pin, a GND pin and an EPGND pin;

[0027] The IN pin of the LDO chip serves as the input end of the voltage control circuit, the OUT pin of the LDO chip is connected to one end of the inductor L3, and the other end of the inductor L3 serves as the output end of the voltage control circuit and outputs the voltage MCU_POWER;

[0028] The IN pin of the LDO chip is also connected to one end of the resistor R3 and one end of the capacitor C4 respectively, the other end of the resistor R3 is connected to one end of the resistor R4 and the EN pin of the LDO chip respectively, and the other end of the capacitor C4 and the other end of the resistor R4 are both grounded;

[0029] The OUT pin of the LDO chip is also connected to one end of the resistor R5, one end of the resistor R7, one end of the capacitor C6, one end of the capacitor C7 and one end of the capacitor C8 respectively, the other end of the resistor R5 is connected to the RESET pin of the LDO chip, the other end of the resistor R7 is connected to the ADJ pin of the LDO chip, the other end of the capacitor C6 and one end of the resistor R6 respectively, and the other end of the resistor R6, the other end of the capacitor C7 and the other end of the capacitor C8 are all grounded;

[0030] The TO pin of the LDO chip is connected to one end of the capacitor C5, and the other end of the capacitor C5 is grounded;

[0031] The NC pin of the LDO chip is left empty, and the GND pin and the EPGND pin of the LDO chip are both grounded;

[0032] The voltage control circuit uses a power step-down chip to step down the output voltage of the first output terminal of the main line circuit, and supplies power to the MCU, and serves as a pull-up voltage for the high and low voltage interrupt detection circuit and the voltage sampling circuit.

[0033] Preferably, the high and low voltage interrupt detection circuit comprises: a window voltage comparator U2, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a capacitor C9, a capacitor C10, a capacitor C11, a capacitor C12 and a Schottky diode D3;

[0034] The window voltage comparator U2 includes: a +INA pin, a -INA pin, an OUTA pin, a +INB pin, a -INB pin, an OUTB pin, a V+ pin and a V- pin;

[0035] The +INA pin of the window voltage comparator U2 is respectively connected to one end of the resistor R8, one end of the resistor R12 and one end of the capacitor C10, and the other end of the resistor R8 serves as the first input end of the high and low voltage interrupt detection circuit; the other end of the resistor R12 and the other end of the capacitor C10 are both grounded;

[0036] The -INB pin of the window voltage comparator U2 is respectively connected to one end of the resistor R9, one end of the resistor R13 and one end of the capacitor C11, and the other end of the resistor R9 is connected to the other end of the resistor R8; the other end of the resistor R13 and the other end of the capacitor C11 are both grounded;

[0037] The -INA pin of the window voltage comparator U2 is respectively connected to the +INB pin of the window voltage comparator U2, one end of the resistor R10, one end of the resistor R14 and one end of the capacitor C12; the other end of the resistor R14 and the other end of the capacitor C12 are both grounded;

[0038] The other end of the resistor R10 is respectively connected to the V+ pin of the window voltage comparator U2, one end of the resistor R11 and one end of the capacitor C9, and serves as the second input end of the high and low voltage interrupt detection circuit; the other end of the capacitor C9 is grounded;

[0039] The other end of the resistor R11 is connected to the cathode of the Schottky diode D3 and serves as the output end of the high and low voltage interrupt detection circuit, outputting a signal PWR_LOW_INT to the first signal input end of the micro control unit MCU;

[0040] The anode of the Schottky diode D3 is connected to the OUTA pin and the OUTB pin of the window voltage comparator U2 respectively;

[0041] The V-pin of the window voltage comparator U2 is grounded;

[0042] The high and low voltage interrupt detection circuit uses a window voltage comparator to monitor the voltage range of the first output end of the main line circuit. The voltage range is set with an upper critical value and a lower critical value, and an abnormal interrupt input is given to the MCU; when the voltage of the first output end of the main line circuit exceeds the voltage range, the high and low voltage interrupt detection circuit sends an interrupt signal to the MCU, and the MCU turns off the main switch of the main line circuit to achieve power protection.

[0043] Preferably, the voltage sampling circuit comprises: a resistor R15, a resistor R16, a resistor R17, a capacitor C13, a capacitor C14, a capacitor C15, a voltage stabilizing diode D4, a switching diode D5 and a switching diode D6;

[0044] One end of the resistor R15 is respectively connected to one end of the capacitor C13 and the positive electrode of the voltage zener diode D4, and serves as the first input end of the voltage sampling circuit; the other end of the capacitor C13 and the negative electrode of the voltage zener diode D4 are both grounded; the other end of the resistor R15 is respectively connected to one end of the capacitor C14, one end of the resistor R16 and one end of the resistor R17; the other end of the capacitor C14 and the other end of the resistor R16 are both grounded;

[0045] The other end of the resistor R17 is connected to one end of the capacitor C15 and serves as the output end of the voltage sampling circuit to output the signal POW_H / L_DEL to the second signal input end of the microcontroller unit MCU; the other end of the capacitor C15 is grounded;

[0046] The anode of the switching diode D5 serves as the second input terminal of the voltage sampling circuit, the cathode of the switching diode D5 is connected to the anode of the switching diode D6 and the other end of the resistor R17 respectively, and the cathode of the switching diode D6 is grounded;

[0047] The voltage sampling circuit is used to realize the voltage sampling of the first output end of the main line circuit, and input it into the MCU for recording and storage; at the same time, it cooperates redundantly with the high and low voltage interruption detection circuits to eliminate errors, thereby greatly improving the detection accuracy.

[0048] Preferably, the power protection circuit further comprises: a host computer signal detection circuit;

[0049] The first input end of the host computer signal detection circuit is connected to the wake-up signal output end of the host computer; the second input end of the host computer signal detection circuit is connected to the output end of the voltage regulation circuit; and the output end of the host computer signal detection circuit is connected to the third signal input end of the micro control unit MCU.

[0050] Preferably, the host computer signal detection circuit includes: a bipolar transient suppression diode D7, a resistor R18, a resistor R19, a resistor R20, a resistor R21, an inductor L4, a capacitor C16, a capacitor C17, a capacitor C18, a voltage regulator diode D8 and an NPN transistor Q3;

[0051] One end of the bipolar transient suppression diode D7 is respectively connected to the wake-up signal output end of the host computer and one end of the inductor L4, and serves as the first input end of the host computer signal detection circuit; the other end of the bipolar transient suppression diode D7 is grounded;

[0052] The other end of the inductor L4 is connected to one end of the capacitor C16 and one end of the resistor R21 respectively, the other end of the capacitor C16 is grounded, and the other end of the resistor R21 is connected to one end of the resistor R19;

[0053] The other end of the resistor R19 is respectively connected to one end of the resistor R20, one end of the capacitor C17 and the base of the NPN transistor Q3; the other end of the resistor R20, the other end of the capacitor C17 and the emitter of the NPN transistor Q3 are all grounded;

[0054] The positive electrode of the voltage zener diode D8 is connected to one end of the resistor R19, and the negative electrode of the voltage zener diode D8 is connected to the other end of the resistor R19;

[0055] The collector of the NPN transistor Q3 is respectively connected to one end of the resistor R18 and one end of the capacitor C18, and serves as the output end of the host computer signal detection circuit, outputting the signal WAKE_UP_OUT to the third signal input end of the microcontroller unit MCU; the other end of the resistor R18 serves as the second input end of the host computer signal detection circuit; the other end of the capacitor C18 is grounded;

[0056] In order for vehicle-mounted electronic equipment to work under normal voltage conditions, it generally needs to receive a wake-up signal from the upper host. The upper computer signal detection circuit is used to detect the wake-up signal sent by the upper computer and has the function of preventing misjudgment.

[0057] Preferably, the vehicle-mounted electronic equipment includes: a vehicle-mounted display screen;

[0058] The vehicle-mounted display screen includes: any one or more of an instrument screen, a central control screen, a rear display screen and an armrest screen.

[0059] Compared with the prior art, the beneficial effects of the technical solution of the utility model are:

[0060] The utility model provides a vehicle-mounted electronic equipment power supply detection and protection circuit, which is arranged between a power supply and a micro control unit MCU, wherein a control signal output end of the micro control unit MCU is connected to a control end of the vehicle-mounted electronic equipment, and comprises: a trunk line circuit, a voltage regulation circuit, a high and low voltage interruption detection circuit and a voltage sampling circuit; a power supply end of the trunk line circuit is connected to a power supply, an input end of the trunk line circuit is connected to a switch signal output end of the micro control unit MCU, a first output end of the trunk line circuit is respectively connected to an input end of the voltage regulation circuit, a first input end of the high and low voltage interruption detection circuit, and a first input end of the voltage sampling circuit; a second output end of the trunk line circuit is connected to a power supply end of the vehicle-mounted electronic equipment; an output end of the voltage regulation circuit is respectively connected to a power supply end of the micro control unit MCU, a second input end of the high and low voltage interruption detection circuit, and a second input end of the voltage sampling circuit; output ends of the high and low voltage interruption detection circuit and the voltage sampling circuit are respectively connected to a first and a second signal input end of the micro control unit MCU;

[0061] The utility model utilizes a window comparator amplifier and voltage sampling to detect input voltages in real time, and sends the detection results to a microcontroller unit MCU for logic judgment in real time, thereby completing the power supply protection of the electronic equipment. The two cooperate with each other redundantly and eliminate errors from each other, which can multiply the detection accuracy and response rate so as to quickly take countermeasures. The utility model can not only realize the reverse connection protection and electromagnetic interference resistance of the power supply, but also realize systematic quantitative input protection. When the voltage is lower than or exceeds the critical value, the on-board electronic equipment can quickly identify and cut off the abnormal voltage to protect itself and prevent damage to the equipment, thereby realizing power supply protection with high detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 This is a structural block diagram of a vehicle-mounted electronic equipment power supply detection and protection circuit provided in Example 1.

[0063] Figure 2 This is a schematic diagram of the 5a waveform specified for the transient interference surge pulse provided in Example 1.

[0064] Figure 3 This is a schematic diagram of the 5b waveform specified for the transient interference surge pulse provided in Example 1.

[0065] Figure 4 This is a structural block diagram of a vehicle-mounted electronic equipment power supply detection and protection circuit provided in Example 2.

[0066] Figure 5 This is a circuit connection diagram of the trunk line circuit 1 provided in Example 2.

[0067] Figure 6 This is a circuit connection diagram of the voltage control circuit 2 and the high and low voltage interruption detection circuit 3 provided in Example 2.

[0068] Figure 7 This is a circuit connection diagram of the voltage sampling circuit 4 and the host computer signal detection circuit 5 provided in Example 2.

[0069] Figure 8 This is a logic structure diagram of a vehicle-mounted electronic equipment power supply detection and protection circuit provided in Example 2. DETAILED DESCRIPTION

[0070] The drawings are for illustrative purposes only and should not be construed as limiting the present patent;

[0071] In order to better illustrate the present embodiment, some parts in the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product;

[0072] It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0073] The technical solution of the utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0074] Example 1

[0075] like Figure 1 As shown, this embodiment provides a vehicle-mounted electronic device power supply detection and protection circuit, which is arranged between the power supply and the micro control unit MCU, and the control signal output end of the micro control unit MCU is connected to the control end of the vehicle-mounted electronic device, including: a trunk line circuit 1, a voltage regulation circuit 2, a high and low voltage interruption detection circuit 3 and a voltage sampling circuit 4;

[0076] The power supply end of the main line circuit 1 is connected to the power supply, the input end of the main line circuit 1 is connected to the switch signal output end of the micro control unit MCU, the first output end of the main line circuit 1 is respectively connected to the input end of the voltage control circuit 2, the first input end of the high and low voltage interruption detection circuit 3, and the first input end of the voltage sampling circuit 4; the second output end of the main line circuit 1 is connected to the power supply end of the vehicle-mounted electronic device;

[0077] The output end of the voltage control circuit 2 is respectively connected to the power supply end of the micro control unit MCU, the second input end of the high and low voltage interrupt detection circuit 3, and the second input end of the voltage sampling circuit 4;

[0078] The output ends of the high and low voltage interrupt detection circuit 3 and the voltage sampling circuit 4 are respectively connected to the first and second signal input ends of the micro control unit MCU.

[0079] In the specific implementation process, the power protection circuit in this embodiment is used to realize the functions of anti-reverse connection of the power supply of the vehicle-mounted electronic equipment, quantitative overvoltage and undervoltage protection, and anti-electromagnetic interference, so as to ensure that the working voltage of the electronic equipment is within the design requirement range;

[0080] Generally, all electronic components on a car must have voltage detection and protection capabilities, such as on-board displays and low-voltage components. On-board displays include instrument screens, central control screens, rear display screens, and armrest screens. Low-voltage components are relative to motors and battery packs. Common low-voltage components include: entertainment domain controllers, ambient light controllers, air conditioning controllers, head-up display systems (Head-up-Display, HUD), CAN boxes, T-BOX, etc. These 12V system components are all low-voltage components. As long as the components are controlled by MCU, the above circuit can be used. The fundamental purpose of the detection and protection circuit is to protect the components to work normally within the designed voltage range and prevent them from being damaged by high and low voltages.

[0081] Specifically, the main line circuit 1 is the main line of the power protection circuit, which is provided with an anti-electromagnetic interference circuit, an anti-reverse connection circuit and a main switch of the main line; the anti-electromagnetic interference circuit is used to cope with the impact of transient surge pulses and electrostatic discharge (ESD), and realize the first layer of protection of the circuit main line; Figure 2 and Figure 3Two examples of transient surge pulses are shown, namely, waveform 5a and waveform 5b specified in the transient anti-disturbance surge pulse. The anti-reverse connection circuit implements the circuit's positive and negative pole reverse connection protection based on a diode. When the positive and negative poles of the power supply are reversed, the diode is cut off, thereby protecting the subsequent devices. The main trunk line switch includes a switch tube and a transistor. The switch tube serves as the main switch of the power protection circuit to control the on and off of the circuit. The switch of the switch tube is controlled by the transistor, and the transistor is controlled by the switch level signal of the microcontroller unit MCU.

[0082] The input of the main line circuit 1 is an external DC power supply. After being anti-electromagnetic interference and anti-reverse connection, the external DC power is used as the output of the first output terminal, and after passing through the main switch of the main line, it is used as the output of the second output terminal. The output voltage of the second output terminal is used to power the display screen behind.

[0083] The voltage control circuit 2 uses a power step-down chip to step down the output voltage of the first output terminal of the main line circuit 1, and supplies power to the MCU, and serves as a pull-up voltage for the high and low voltage interrupt detection circuit 3 and the voltage sampling circuit 4;

[0084] The high and low voltage interrupt detection circuit 3 uses a window voltage comparator to monitor the voltage range of the first output terminal of the main line circuit 1 (set an upper limit critical value and a lower limit critical value), and performs an abnormal interrupt input to the MCU; when the voltage of the first output terminal of the main line circuit 1 exceeds the voltage range, the high and low voltage interrupt detection circuit 3 sends an interrupt signal to the MCU, and the MCU turns off the main switch of the main line circuit 1 to achieve power protection;

[0085] The voltage sampling circuit 4 is used to implement voltage sampling at the first output end of the main line circuit 1 and input it into the MCU for recording and storage;

[0086] The utility model utilizes a window comparator amplifier and voltage sampling to detect input voltages in real time, and sends the detection results to a microcontroller unit MCU for logic judgment in real time, thereby completing the power supply protection of the electronic equipment. The cooperation between the two can multiply the detection accuracy and response rate, so as to quickly make countermeasures; the utility model can not only realize the reverse connection protection and electromagnetic interference resistance of the power supply, but also realize systematic quantitative input protection. When the voltage is lower than or exceeds the critical value, the on-board electronic equipment can quickly identify and cut off the abnormal voltage to protect itself and prevent damage to the equipment, thereby realizing power supply protection with high detection accuracy.

[0087] Example 2

[0088] like Figure 4As shown, this embodiment provides a vehicle-mounted electronic device power supply detection and protection circuit, which is arranged between the power supply and the micro control unit MCU, and the control signal output end of the micro control unit MCU is connected to the control end of the vehicle-mounted electronic device, including: a trunk line circuit 1, a voltage regulation circuit 2, a high and low voltage interruption detection circuit 3, a voltage sampling circuit 4 and a host computer signal detection circuit 5;

[0089] The power supply end of the main line circuit 1 is connected to the power supply, the input end of the main line circuit 1 is connected to the switch signal output end of the micro control unit MCU, the first output end of the main line circuit 1 is respectively connected to the input end of the voltage control circuit 2, the first input end of the high and low voltage interruption detection circuit 3, and the first input end of the voltage sampling circuit 4; the second output end of the main line circuit 1 is connected to the power supply end of the vehicle-mounted electronic device;

[0090] The output end of the voltage control circuit 2 is respectively connected to the power supply end of the micro control unit MCU, the second input end of the high and low voltage interrupt detection circuit 3, and the second input end of the voltage sampling circuit 4;

[0091] The output ends of the high and low voltage interrupt detection circuit 3 and the voltage sampling circuit 4 are respectively connected to the first and second signal input ends of the micro control unit MCU;

[0092] The first input end of the host computer signal detection circuit 5 is connected to the wake-up signal output end of the host computer; the second input end of the host computer signal detection circuit 5 is connected to the output end of the voltage control circuit 2; the output end of the host computer signal detection circuit 5 is connected to the third signal input end of the micro control unit MCU;

[0093] like Figure 5 As shown, the main line circuit 1 includes: a bipolar transient suppression diode D1, a power diode D2, a resistor R1, a resistor R2, an NPN transistor Q1, a PMOS transistor Q2, an inductor L1, an inductor L2, a capacitor C1, a capacitor C2 and a capacitor C3;

[0094] One end of the bipolar transient suppression diode D1 is connected to a power supply and serves as a power supply end of the main line circuit 1; the other end of the bipolar transient suppression diode D1 is grounded;

[0095] The first output end of the main line circuit 1 is also connected to one end of the resistor R2 and the source of the PMOS tube Q2 respectively; the other end of the resistor R2 is connected to one end of the resistor R1 and the gate of the PMOS tube Q2 respectively;

[0096] The other end of the resistor R1 is connected to the collector of the NPN transistor Q1, the emitter of the NPN transistor Q1 is grounded, and the base of the NPN transistor Q1 is connected to the switch signal output end of the micro control unit MCU as the input end of the main line circuit 1;

[0097] The anode of the power diode D2 is connected to a power source, one end of the inductor L1 is connected to the cathode of the power diode D2, and the other end of the inductor L1 serves as the first output end of the main line circuit 1 and outputs a voltage VBAT_IN;

[0098] The other end of the inductor L1 is also connected to one end of the capacitor C1 and one end of the capacitor C2 respectively, and the other end of the capacitor C1 and the other end of the capacitor C2 are both grounded;

[0099] One end of the inductor L2 is connected to the drain of the PMOS tube Q2 and one end of the capacitor C3 respectively, and the other end of the inductor L2 serves as the second output end of the main line circuit 1 and outputs the voltage VBAT_OUT;

[0100] The other end of the capacitor C3 is grounded;

[0101] The voltage control circuit 2 controls the voltage of the first output terminal of the main line circuit 1 through the power chip U1;

[0102] The power chip U1 includes any one of a DCDC chip and an LDO chip;

[0103] like Figure 6 As shown, the voltage control circuit 2 includes: an LDO chip, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, an inductor L3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7 and a capacitor C8;

[0104] The LDO chip includes: an IN pin, an OUT pin, an EN pin, a RESET pin, an ADJ pin, a TO pin, an NC pin, a GND pin and an EPGND pin;

[0105] The IN pin of the LDO chip serves as the input end of the voltage control circuit 2, the OUT pin of the LDO chip is connected to one end of the inductor L3, and the other end of the inductor L3 serves as the output end of the voltage control circuit 2 and outputs the voltage MCU_POWER;

[0106] The IN pin of the LDO chip is also connected to one end of the resistor R3 and one end of the capacitor C4 respectively, the other end of the resistor R3 is connected to one end of the resistor R4 and the EN pin of the LDO chip respectively, and the other end of the capacitor C4 and the other end of the resistor R4 are both grounded;

[0107] The OUT pin of the LDO chip is also connected to one end of the resistor R5, one end of the resistor R7, one end of the capacitor C6, one end of the capacitor C7 and one end of the capacitor C8 respectively, the other end of the resistor R5 is connected to the RESET pin of the LDO chip, the other end of the resistor R7 is connected to the ADJ pin of the LDO chip, the other end of the capacitor C6 and one end of the resistor R6 respectively, and the other end of the resistor R6, the other end of the capacitor C7 and the other end of the capacitor C8 are all grounded;

[0108] The TO pin of the LDO chip is connected to one end of the capacitor C5, and the other end of the capacitor C5 is grounded;

[0109] The NC pin of the LDO chip is left empty, and the GND pin and the EPGND pin of the LDO chip are both grounded;

[0110] The high and low voltage interrupt detection circuit 3 includes: a window voltage comparator U2, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a capacitor C9, a capacitor C10, a capacitor C11, a capacitor C12 and a Schottky diode D3;

[0111] The window voltage comparator U2 includes: a +INA pin, a -INA pin, an OUTA pin, a +INB pin, a -INB pin, an OUTB pin, a V+ pin and a V- pin;

[0112] The +INA pin of the window voltage comparator U2 is respectively connected to one end of the resistor R8, one end of the resistor R12 and one end of the capacitor C10, and the other end of the resistor R8 serves as the first input end of the high and low voltage interrupt detection circuit 3; the other end of the resistor R12 and the other end of the capacitor C10 are both grounded;

[0113] The -INB pin of the window voltage comparator U2 is respectively connected to one end of the resistor R9, one end of the resistor R13 and one end of the capacitor C11, and the other end of the resistor R9 is connected to the other end of the resistor R8; the other end of the resistor R13 and the other end of the capacitor C11 are both grounded;

[0114] The -INA pin of the window voltage comparator U2 is respectively connected to the +INB pin of the window voltage comparator U2, one end of the resistor R10, one end of the resistor R14 and one end of the capacitor C12; the other end of the resistor R14 and the other end of the capacitor C12 are both grounded;

[0115] The other end of the resistor R10 is respectively connected to the V+ pin of the window voltage comparator U2, one end of the resistor R11 and one end of the capacitor C9, and serves as the second input end of the high and low voltage interrupt detection circuit 3; the other end of the capacitor C9 is grounded;

[0116] The other end of the resistor R11 is connected to the cathode of the Schottky diode D3 and serves as the output end of the high and low voltage interrupt detection circuit 3, outputting a signal PWR_LOW_INT to the first signal input end of the micro control unit MCU;

[0117] The anode of the Schottky diode D3 is connected to the OUTA pin and the OUTB pin of the window voltage comparator U2 respectively;

[0118] The V-pin of the window voltage comparator U2 is grounded;

[0119] like Figure 7 As shown, the voltage sampling circuit 4 includes: a resistor R15, a resistor R16, a resistor R17, a capacitor C13, a capacitor C14, a capacitor C15, a voltage stabilizing diode D4, a switching diode D5 and a switching diode D6;

[0120] One end of the resistor R15 is respectively connected to one end of the capacitor C13 and the positive electrode of the voltage zener diode D4, and serves as the first input end of the voltage sampling circuit 4; the other end of the capacitor C13 and the negative electrode of the voltage zener diode D4 are both grounded; the other end of the resistor R15 is respectively connected to one end of the capacitor C14, one end of the resistor R16 and one end of the resistor R17; the other end of the capacitor C14 and the other end of the resistor R16 are both grounded;

[0121] The other end of the resistor R17 is connected to one end of the capacitor C15 and serves as the output end of the voltage sampling circuit 4 to output the signal POW_H / L_DEL to the second signal input end of the microcontroller unit MCU; the other end of the capacitor C15 is grounded;

[0122] The positive electrode of the switching diode D5 serves as the second input terminal of the voltage sampling circuit (4), the negative electrode of the switching diode D5 is respectively connected to the positive electrode of the switching diode D6 and the other end of the resistor R17, and the negative electrode of the switching diode D6 is grounded;

[0123] The host computer signal detection circuit 5 includes: a bipolar transient suppression diode D7, a resistor R18, a resistor R19, a resistor R20, a resistor R21, an inductor L4, a capacitor C16, a capacitor C17, a capacitor C18, a voltage regulator diode D8 and an NPN transistor Q3;

[0124] One end of the bipolar transient suppression diode D7 is respectively connected to the wake-up signal output end of the host computer and one end of the inductor L4, and serves as the first input end of the host computer signal detection circuit 5; the other end of the bipolar transient suppression diode D7 is grounded;

[0125] The other end of the inductor L4 is connected to one end of the capacitor C16 and one end of the resistor R21 respectively, the other end of the capacitor C16 is grounded, and the other end of the resistor R21 is connected to one end of the resistor R19;

[0126] The other end of the resistor R19 is respectively connected to one end of the resistor R20, one end of the capacitor C17 and the base of the NPN transistor Q3; the other end of the resistor R20, the other end of the capacitor C17 and the emitter of the NPN transistor Q3 are all grounded;

[0127] The positive electrode of the voltage zener diode D8 is connected to one end of the resistor R19, and the negative electrode of the voltage zener diode D8 is connected to the other end of the resistor R19;

[0128] The collector of the NPN transistor Q3 is respectively connected to one end of the resistor R18 and one end of the capacitor C18, and serves as the output end of the host computer signal detection circuit 5, outputting the signal WAKE_UP_OUT to the third signal input end of the microcontroller unit MCU; the other end of the resistor R18 serves as the second input end of the host computer signal detection circuit 5; the other end of the capacitor C18 is grounded;

[0129] The vehicle-mounted electronic equipment includes: a vehicle-mounted display screen;

[0130] The vehicle-mounted display screen includes: any one or more of an instrument screen, a central control screen, a rear display screen and an armrest screen.

[0131] In the specific implementation process, the power protection circuit in this embodiment is used to realize the functions of anti-reverse connection of the power supply of the vehicle display screen, quantitative overvoltage and undervoltage protection, and anti-electromagnetic interference, so as to ensure that the working voltage of the display screen is within the design requirement range. Its architecture is as follows Figure 8 As shown; specifically used in various vehicle-mounted display screens such as instrument screens, central control screens, rear display screens and armrest screens;

[0132] At present, the DC power supply system of passenger cars is 12V, but in actual vehicles, the DC voltage is often not an ideal constant value. It is generally believed that 9V to 14V are all in the normal power supply range, and the components are required to be able to work normally within this voltage range; but if the voltage continues to decrease or increase in abnormal voltage, the circuit system in the component must be able to identify and control the abnormal voltage to protect itself and prevent damage; this embodiment stipulates that: 9V or less is low voltage, and 14V or more is high voltage. In actual use, the critical values ​​of high and low voltages can be adjusted according to design requirements;

[0133] Specifically, the main line circuit 1 is the main line of the power protection circuit, which is provided with an anti-electromagnetic interference circuit, an anti-reverse connection circuit and a main switch of the main line; the anti-electromagnetic interference circuit is used to cope with the impact of transient surge pulses and electrostatic discharge (ESD), and realize the first layer of protection of the circuit main line; Figure 2 and Figure 3 Two examples of transient surge pulses are shown, namely, waveform 5a and waveform 5b specified in the transient anti-disturbance surge pulse. The anti-reverse connection circuit implements the circuit's positive and negative pole reverse connection protection based on a diode. When the positive and negative poles of the power supply are reversed, the diode is cut off, thereby protecting the subsequent devices. The main trunk line switch includes a switch tube and a transistor. The switch tube serves as the main switch of the power protection circuit to control the on and off of the circuit. The switch of the switch tube is controlled by the transistor, and the transistor is controlled by the switch level signal of the microcontroller unit MCU.

[0134] The input of the main line circuit 1 is an external DC power supply. After being anti-electromagnetic interference and anti-reverse connection, the external DC power is used as the output of the first output terminal, and after passing through the main switch of the main line, it is used as the output of the second output terminal. The output voltage of the second output terminal is used to power the display screen behind.

[0135] like Figure 5 In the circuit shown, the DC network on the left is connected to the external DC power supply through a connector. D1 is a bipolar TVS tube, which is mainly used to deal with high-voltage shocks such as voltage surges and static electricity. The power diode D2 can prevent reverse polarity. When the positive power passes through the D2 diode smoothly, it passes through the filter circuit of the L1 inductor, C1, and C2 capacitors and reaches the PMOS tube of Q2. Q2 is the main switch of the system power supply, and its conduction is controlled by the level signal output by the MCU to the base of the Q1 transistor. R1 and R2 are the gate voltage divider resistors of Q1. When V G <V S When the source-drain of Q1 is turned on; C3 and L2 are VBAT_OUT output line filter components; VBAT_OUT is the EN enable of the following BUCK, BOOST and others (such as the video decoding module at the screen end) that need to be controlled by the MCU output control module, so that the timing circuit between the modules can be formed to ensure that there is no abnormal screen when the screen is powered on and off;

[0136] like Figure 6In the shown circuit, the voltage regulation circuit 2 uses a power supply buck chip to step down the output voltage of the first output terminal of the main line circuit 1, supply power to the MCU, and serve as the pull-up voltage for the high and low voltage interruption detection circuit 3 and the voltage sampling circuit 4; the power supply chip U1 can select DCDC or LDO according to requirements. Generally, the power consumption requirement of the MCU is small, so in this embodiment, LDO is selected; the power input of the LDO is VBAT_IN, and the output terminal is MCU_POWER (generally 3.3V); C4, C7, C8, and L3 are line filtering and energy storage components; C5 is the reset delay capacitor of the LDO chip; R3, R4, R5, R6, and R7 are voltage dividing or current limiting resistors.

[0137] The high and low voltage interruption detection circuit 3 uses a window voltage comparator to monitor the voltage range (set the upper limit critical value and the lower limit critical value) of the first output terminal of the main line circuit 1, and inputs an abnormal interruption to the MCU; when the voltage of the first output terminal of the main line circuit 1 exceeds the voltage range, the high and low voltage interruption detection circuit 3 sends an interruption signal to the MCU, and the MCU closes the main switch of the main line circuit 1 to achieve power protection.

[0138] As Figure 6 In the shown circuit, U2 is a window voltage comparison amplifier, whose purpose is to monitor the voltage range of VBAT_IN and input an abnormal interruption to the MCU; PIN8 is the working voltage input port of this module; the MCU_POWER voltage is divided by R10 and R14 and then used as the reference voltage V_B of the comparator and input to PIN2 and PIN5; R8, R9, R12, and R13 are the window voltage dividing resistors for inputting the VBAT_IN voltage to PIN3 and PIN6. The specific resistance values are selected after calculation according to the low voltage of 9V and the high voltage of 14V. The divided voltage levels are used as the upper limit V_H and the lower limit V_L window reference voltages of the operational amplifier; C10, C11, and C12 are discharge capacitors, which are used to reduce the input hysteresis. D3 is a Schottky diode, whose purpose is to quickly output the response and prevent abnormal level backflow.

[0139] The VBAT_IN voltage is respectively input to PIN3 and PIN6 after passing through the window voltage dividing resistors; during design, when the resistance values of R8 and R9 are the same, then R12 > R13; 9V forms the V_H value after voltage division and is input to PIN3, and 14V forms the V_L lower limit value after voltage division and is input to PIN6; when V_L < V_B < V_H, the output of U2 is high level. Once overvoltage and undervoltage occur in VBAT_IN, V_H and V_L will change accordingly, and V_B will no longer be between them. The PIN1 or PIN7 of the U2 comparator outputs low level. At this time, the MCU makes corresponding interruption actions according to the change of PWR_LOW_INTT.

[0140] The voltage sampling circuit 4 is used to implement voltage sampling at the first output end of the main line circuit 1 and input it into the MCU for recording and storage;

[0141] like Figure 7 In the circuit shown, this part is the AD sampling of VBAT_IN voltage and the detection circuit of WAKE_UP; the principle of AD sampling is to use R15 and R16 series resistors to divide the voltage, POW_H / L_DET is the sampled value of VBAT_IN after proportional reduction, and then passes through the current limiting resistor of R17 to ensure that the AD sampled value is within the range that the MCU can recognize and withstand, thereby representing the voltage range of VABT_IN, and recording the data in the MCU memory for easy MCU retrieval; C13, C14, and C15 are filtering and decoupling capacitors; D4 is a voltage regulator diode, and D5 is a switching diode, so that the upper limit of POW_H / L_DET output is the MCU_POWER value to prevent damage to the GPIO port;

[0142] In this embodiment, D5-D6 are switching diodes in SOT23 package, typically BAV99, which is composed of two switching diodes. The design here is based on the principle of unidirectional conduction and clamping voltage of the diode to limit the amplitude of the sampling voltage output to prevent the sampling voltage from being too large or too small, causing abnormal AD conversion of the MCU. If the forward conduction voltage of the diode (usually 0.6V) is not considered, Figure 7 The circuit will limit the POW_H / L_DET sampling output voltage between the GND voltage and the MCU_POWER voltage; the grounded diode limits the lower limit, and the diode connected to MCU_POWER is the upper limit; in practice, it is more about dealing with the upper limit, and also protects the MCU's GPIO port from being broken down by high voltage;

[0143] Due to the problem of resistor accuracy and PCBA circuit board patch process, there will be individual differences in AD sampling value and window voltage, so the window comparator and sampling circuit can cooperate redundantly to eliminate errors. It has been verified that the combination of the two can achieve an accuracy of 0.1V, but if only one of the methods is used, the accuracy can only be 0.3~0.5V at most.

[0144] In order for the display screen to work under normal voltage conditions, it must receive a WAKP_UP wake-up signal from the upper host, so this embodiment also provides an upper computer signal detection circuit 5; in order to prevent misjudgment of input, the WAKP_UP level is input to the Q3 transistor through the R19, R20, and R21 voltage divider resistors, and D8 is a reserved voltage regulator diode; if it meets the expected settings, WAKE_UP_OUT will be input to the MCU for judgment based on the changes in the input end;

[0145] After the microcontroller unit MCU detects that the high and low voltage interrupt signal PWR_LOW_INT, the B+ sampling signal POW_H / L_DET, and the wake-up signal WAKE_UP_OUT are all at the expected normal setting level, it turns on the POW_ON signal to make the emitter of Q1 forward biased, and finally turns on the PMOS tube of Q2 to power the subsequent display screen; the GPIO of the MCU controls the display screen EN enable according to the timing setting;

[0146] The utility model utilizes a window comparator amplifier and voltage sampling to detect input voltages in real time, and sends the detection results to a microcontroller unit MCU for logic judgment in real time, thereby completing the power supply protection of the electronic equipment. The cooperation between the two can multiply the detection accuracy and response rate, so as to quickly make countermeasures; the utility model can not only realize the reverse connection protection and electromagnetic interference resistance of the power supply, but also realize systematic quantitative input protection. When the voltage is lower than or exceeds the critical value, the on-board electronic equipment can quickly identify and cut off the abnormal voltage to protect itself and prevent damage to the equipment, thereby realizing power supply protection with high detection accuracy.

[0147] The same or similar reference numerals correspond to the same or similar components;

[0148] The terms used in the drawings to describe positional relationships are only used for illustrative purposes and should not be construed as limiting this patent;

[0149] Obviously, the above embodiments of the utility model are only examples for clearly explaining the utility model, and are not intended to limit the implementation methods of the utility model. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to list all the implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the utility model should be included in the protection scope of the claims of the utility model.

Claims

1. A power supply detection and protection circuit for an on-board electronic device, arranged between a power supply and a microcontroller unit MCU, wherein a control signal output terminal of the microcontroller unit MCU is connected to a control terminal of the on-board electronic device, characterized in that: include: Main line circuit (1), voltage regulation circuit (2), high and low voltage interruption detection circuit (3) and voltage sampling circuit (4); The power supply end of the main line circuit (1) is connected to a power source, the input end of the main line circuit (1) is connected to a switch signal output end of the micro control unit MCU, the first output end of the main line circuit (1) is respectively connected to the input end of the voltage control circuit (2), the first input end of the high and low voltage interruption detection circuit (3), and the first input end of the voltage sampling circuit (4); the second output end of the main line circuit (1) is connected to the power supply end of the vehicle-mounted electronic device; The output end of the voltage control circuit (2) is respectively connected to the power supply end of the micro control unit MCU, the second input end of the high and low voltage interruption detection circuit (3), and the second input end of the voltage sampling circuit (4); The output ends of the high and low voltage interrupt detection circuit (3) and the voltage sampling circuit (4) are respectively connected to the first and second signal input ends of the micro control unit MCU.

2. The vehicle-mounted electronic equipment power supply detection and protection circuit according to claim 1, characterized in that: The main line circuit (1) comprises: a bipolar transient suppression diode D1, a power diode D2, a resistor R1, a resistor R2, an NPN transistor Q1 and a PMOS transistor Q2; One end of the bipolar transient suppression diode D1 is connected to a power source and serves as a power supply end of the main line circuit (1); the other end of the bipolar transient suppression diode D1 is grounded; The positive electrode of the power diode D2 is connected to a power supply, and the negative electrode of the power diode D2 serves as a first output terminal of the main line circuit (1) and outputs a voltage VBAT_IN; The first output end of the main line circuit (1) is also connected to one end of the resistor R2 and the source of the PMOS tube Q2 respectively; the other end of the resistor R2 is connected to one end of the resistor R1 and the gate of the PMOS tube Q2 respectively; the drain of the PMOS tube Q2 serves as the second output end of the main line circuit (1) and outputs the voltage VBAT_OUT; The other end of the resistor R1 is connected to the collector of the NPN transistor Q1, the emitter of the NPN transistor Q1 is grounded, and the base of the NPN transistor Q1 is connected to the switch signal output end of the micro control unit MCU as the input end of the main line circuit (1).

3. The vehicle-mounted electronic equipment power supply detection and protection circuit according to claim 2, characterized in that: The main line circuit (1) further comprises: an inductor L1, an inductor L2, a capacitor C1, a capacitor C2 and a capacitor C3; One end of the inductor L1 is connected to the cathode of the power diode D2, and the other end of the inductor L1 serves as the first output end of the main line circuit (1); The other end of the inductor L1 is also connected to one end of the capacitor C1 and one end of the capacitor C2 respectively, and the other end of the capacitor C1 and the other end of the capacitor C2 are both grounded; One end of the inductor L2 is respectively connected to the drain of the PMOS tube Q2 and one end of the capacitor C3, and the other end of the inductor L2 serves as the second output end of the main line circuit (1); The other end of the capacitor C3 is grounded.

4. The vehicle-mounted electronic equipment power supply detection and protection circuit according to claim 1, characterized in that: The voltage control circuit (2) controls the voltage at the first output end of the main line circuit (1) through the power chip U1; The power chip U1 includes any one of a DCDC chip and a LDO chip.

5. The vehicle-mounted electronic equipment power supply detection and protection circuit according to claim 4, characterized in that: The voltage control circuit (2) comprises: an LDO chip, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, an inductor L3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7 and a capacitor C8; The LDO chip includes: an IN pin, an OUT pin, an EN pin, a RESET pin, an ADJ pin, a TO pin, an NC pin, a GND pin and an EPGND pin; The IN pin of the LDO chip serves as the input end of the voltage control circuit (2), the OUT pin of the LDO chip is connected to one end of the inductor L3, and the other end of the inductor L3 serves as the output end of the voltage control circuit (2) and outputs the voltage MCU_POWER; The IN pin of the LDO chip is also connected to one end of the resistor R3 and one end of the capacitor C4 respectively, the other end of the resistor R3 is connected to one end of the resistor R4 and the EN pin of the LDO chip respectively, and the other end of the capacitor C4 and the other end of the resistor R4 are both grounded; The OUT pin of the LDO chip is also connected to one end of the resistor R5, one end of the resistor R7, one end of the capacitor C6, one end of the capacitor C7 and one end of the capacitor C8 respectively, the other end of the resistor R5 is connected to the RESET pin of the LDO chip, the other end of the resistor R7 is connected to the ADJ pin of the LDO chip, the other end of the capacitor C6 and one end of the resistor R6 respectively, and the other end of the resistor R6, the other end of the capacitor C7 and the other end of the capacitor C8 are all grounded; The TO pin of the LDO chip is connected to one end of the capacitor C5, and the other end of the capacitor C5 is grounded; The NC pin of the LDO chip is left empty, and the GND pin and the EPGND pin of the LDO chip are both grounded.

6. The vehicle-mounted electronic equipment power supply detection and protection circuit according to claim 1, characterized in that: The high and low voltage interrupt detection circuit (3) comprises: a window voltage comparator U2, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a capacitor C9, a capacitor C10, a capacitor C11, a capacitor C12 and a Schottky diode D3; The window voltage comparator U2 includes: a +INA pin, a -INA pin, an OUTA pin, a +INB pin, a -INB pin, an OUTB pin, a V+ pin and a V- pin; The +INA pin of the window voltage comparator U2 is respectively connected to one end of a resistor R8, one end of a resistor R12 and one end of a capacitor C10, the other end of the resistor R8 serves as the first input end of the high and low voltage interrupt detection circuit (3); the other end of the resistor R12 and the other end of the capacitor C10 are both grounded; The -INB pin of the window voltage comparator U2 is respectively connected to one end of the resistor R9, one end of the resistor R13 and one end of the capacitor C11, and the other end of the resistor R9 is connected to the other end of the resistor R8; the other end of the resistor R13 and the other end of the capacitor C11 are both grounded; The -INA pin of the window voltage comparator U2 is respectively connected to the +INB pin of the window voltage comparator U2, one end of the resistor R10, one end of the resistor R14 and one end of the capacitor C12; the other end of the resistor R14 and the other end of the capacitor C12 are both grounded; The other end of the resistor R10 is respectively connected to the V+ pin of the window voltage comparator U2, one end of the resistor R11 and one end of the capacitor C9, and serves as the second input end of the high and low voltage interrupt detection circuit (3); the other end of the capacitor C9 is grounded; The other end of the resistor R11 is connected to the cathode of the Schottky diode D3 and serves as the output end of the high and low voltage interrupt detection circuit (3), outputting a signal PWR_LOW_INT to the first signal input end of the micro control unit MCU; The anode of the Schottky diode D3 is connected to the OUTA pin and the OUTB pin of the window voltage comparator U2 respectively; The V- pin of the window voltage comparator U2 is grounded.

7. The vehicle-mounted electronic equipment power supply detection and protection circuit according to claim 1, characterized in that: The voltage sampling circuit (4) comprises: a resistor R15, a resistor R16, a resistor R17, a capacitor C13, a capacitor C14, a capacitor C15, a voltage stabilizing diode D4, a switching diode D5 and a switching diode D6; One end of the resistor R15 is respectively connected to one end of the capacitor C13 and the positive electrode of the voltage-stabilizing diode D4, and serves as the first input end of the voltage sampling circuit (4); the other end of the capacitor C13 and the negative electrode of the voltage-stabilizing diode D4 are both grounded; the other end of the resistor R15 is respectively connected to one end of the capacitor C14, one end of the resistor R16 and one end of the resistor R17; the other end of the capacitor C14 and the other end of the resistor R16 are both grounded; The other end of the resistor R17 is connected to one end of the capacitor C15 and serves as the output end of the voltage sampling circuit (4), outputting a signal POW_H / L_DEL to a second signal input end of the microcontroller unit MCU; the other end of the capacitor C15 is grounded; The anode of the switching diode D5 serves as the second input terminal of the voltage sampling circuit (4), the cathode of the switching diode D5 is respectively connected to the anode of the switching diode D6 and the other end of the resistor R17, and the cathode of the switching diode D6 is grounded.

8. The vehicle-mounted electronic equipment power supply detection and protection circuit according to claim 1, characterized in that: The power protection circuit further comprises: a host computer signal detection circuit (5); The first input end of the host computer signal detection circuit (5) is connected to the wake-up signal output end of the host computer; the second input end of the host computer signal detection circuit (5) is connected to the output end of the voltage control circuit (2); and the output end of the host computer signal detection circuit (5) is connected to the third signal input end of the micro control unit MCU.

9. The vehicle-mounted electronic equipment power supply detection and protection circuit according to claim 8, characterized in that: The host computer signal detection circuit (5) comprises: a bipolar transient suppression diode D7, a resistor R18, a resistor R19, a resistor R20, a resistor R21, an inductor L4, a capacitor C16, a capacitor C17, a capacitor C18, a voltage stabilizing diode D8 and an NPN transistor Q3; One end of the bipolar transient suppression diode D7 is respectively connected to the wake-up signal output end of the host computer and one end of the inductor L4, and serves as the first input end of the host computer signal detection circuit (5); the other end of the bipolar transient suppression diode D7 is grounded; The other end of the inductor L4 is connected to one end of the capacitor C16 and one end of the resistor R21 respectively, the other end of the capacitor C16 is grounded, and the other end of the resistor R21 is connected to one end of the resistor R19; The other end of the resistor R19 is respectively connected to one end of the resistor R20, one end of the capacitor C17 and the base of the NPN transistor Q3; the other end of the resistor R20, the other end of the capacitor C17 and the emitter of the NPN transistor Q3 are all grounded; The positive electrode of the voltage zener diode D8 is connected to one end of the resistor R19, and the negative electrode of the voltage zener diode D8 is connected to the other end of the resistor R19; The collector of the NPN transistor Q3 is respectively connected to one end of the resistor R18 and one end of the capacitor C18, and serves as the output end of the host computer signal detection circuit (5), outputting a signal WAKE_UP_OUT to the third signal input end of the micro control unit MCU; the other end of the resistor R18 serves as the second input end of the host computer signal detection circuit (5); and the other end of the capacitor C18 is grounded.

10. A vehicle-mounted electronic equipment power supply detection and protection circuit according to any one of claims 1 to 9, characterized in that: The vehicle-mounted electronic equipment includes: a vehicle-mounted display screen; The vehicle-mounted display screen includes: any one or more of an instrument screen, a central control screen, a rear display screen and an armrest screen.

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