WO2020238864A1 - 过压保护电路 - Google Patents

过压保护电路 Download PDF

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Publication number
WO2020238864A1
WO2020238864A1 PCT/CN2020/092160 CN2020092160W WO2020238864A1 WO 2020238864 A1 WO2020238864 A1 WO 2020238864A1 CN 2020092160 W CN2020092160 W CN 2020092160W WO 2020238864 A1 WO2020238864 A1 WO 2020238864A1
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WO
WIPO (PCT)
Prior art keywords
circuit
voltage
electrically connected
resistor
input terminal
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Application number
PCT/CN2020/092160
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English (en)
French (fr)
Inventor
秦威
Original Assignee
深圳市道通智能航空技术有限公司
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Application filed by 深圳市道通智能航空技术有限公司 filed Critical 深圳市道通智能航空技术有限公司
Publication of WO2020238864A1 publication Critical patent/WO2020238864A1/zh

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/20—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/20—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage
    • H02H3/202—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage for dc systems

Definitions

  • This application relates to the field of circuit protection, and in particular to an overvoltage protection circuit.
  • the power supply circuit is generally protected against overvoltage.
  • a reasonable circuit design can avoid damage to the product and prolong the service life of the product.
  • proper circuit design is crucial to the circuit.
  • the current used is very large, and the voltage is very high.
  • the conventional negative terminal protection circuit often burns the device because it is not turned off in time.
  • the existing overvoltage protection is mostly a program control method, and program failures such as program runaway and latching may occur, and the stability of the overvoltage protection is too low.
  • the main purpose of the present invention is to provide an overvoltage protection circuit, which aims to solve the technical problem of low stability of the existing overvoltage protection.
  • the present invention provides an overvoltage protection circuit, which is used to provide overvoltage protection between the positive input terminal and the positive output terminal of an external circuit, the overvoltage protection circuit includes:
  • a switch circuit the switch circuit is electrically connected to the positive input terminal and the positive output terminal, and the switch circuit is used to control the electrical on/off between the positive input terminal and the positive output terminal;
  • An overvoltage detection circuit the overvoltage detection circuit is electrically connected to the positive input terminal, and the overvoltage detection circuit is configured to output an overvoltage signal when detecting that the voltage at the positive input terminal exceeds a preset voltage;
  • a voltage comparison circuit the voltage comparison circuit is electrically connected to the overvoltage detection circuit, the voltage comparison circuit is configured to output a disconnection signal after receiving the overvoltage signal;
  • a control circuit which is electrically connected to the voltage comparison circuit and the switch circuit, respectively, and the control circuit is configured to output a switch-off signal to the switch circuit after receiving the switch-off signal;
  • the switch circuit is also used to disconnect the electrical connection between the positive input terminal and the positive output terminal after receiving the turn-off signal.
  • the overvoltage protection circuit further includes a hysteresis circuit, the hysteresis circuit is electrically connected to the voltage comparison circuit, and the hysteresis circuit is used to change the voltage at the positive input terminal from greater than the preset voltage to When the voltage is equal to the preset voltage, the voltage comparison circuit is controlled to hysterically stop outputting the disconnect signal.
  • a hysteresis circuit the hysteresis circuit is electrically connected to the voltage comparison circuit, and the hysteresis circuit is used to change the voltage at the positive input terminal from greater than the preset voltage to When the voltage is equal to the preset voltage, the voltage comparison circuit is controlled to hysterically stop outputting the disconnect signal.
  • the voltage comparison circuit includes a voltage stabilizing source, a comparator, a first voltage dividing element and a second voltage dividing element, and the output terminal of the voltage stabilizing source is respectively connected to the first voltage dividing element and the second voltage dividing element.
  • the voltage dividing element is electrically connected, the first voltage dividing element is electrically connected to the inverting input terminal of the comparator and the overvoltage detection circuit, and the second voltage dividing element is electrically connected to the same of the comparator. It is electrically connected to the input terminal, and the output terminal of the comparator is electrically connected to the control circuit.
  • the first voltage dividing element includes a first resistor and a second resistor, the first end of the first resistor is electrically connected to the output end of the voltage stabilizing source, and the second end of the first resistor Are respectively electrically connected to the first end of the second resistor, the reverse input end of the comparator, and the overvoltage detection circuit; the second end of the second resistor is grounded; the second voltage dividing element It includes a third resistor and a fourth resistor, the first end of the third resistor is electrically connected to the output end of the voltage stabilizing source, and the second end of the third resistor is respectively connected to the first end of the fourth resistor. Terminal and the same direction input terminal of the comparator are electrically connected, and the second terminal of the fourth resistor is grounded.
  • the ratio of the resistance of the first resistor to the resistance of the second resistor is greater than the ratio of the resistance of the third resistor to the resistance of the fourth resistor.
  • the overvoltage protection circuit further includes a hysteresis circuit
  • the hysteresis circuit includes a third voltage dividing element and a first diode
  • the anode of the first diode is electrically connected to the same direction input terminal of the comparator.
  • the cathode of the first diode is electrically connected to the output terminal of the comparator and the third voltage dividing element
  • the third voltage dividing element is also electrically connected to the control circuit.
  • the voltage divider element is also grounded.
  • the overvoltage detection circuit includes a first Zener diode, the cathode of the first Zener diode is electrically connected to the anode input terminal, and the anode of the first Zener diode is electrically connected to the comparator's The reverse input terminal is electrically connected.
  • control circuit includes a control chip
  • control chip includes a first pin and a second pin
  • the output terminal of the comparator is electrically connected to the first pin of the control chip
  • control chip The second pin is electrically connected to the switch circuit.
  • the switch circuit includes a MOS tube, the drain of the MOS tube is electrically connected to the positive input terminal, the source of the MOS tube is electrically connected to the positive output terminal, and the The gate is electrically connected to the control circuit.
  • the MOS tube includes an N-type MOS tube.
  • the overvoltage detection circuit of the present invention detects that the voltage at the positive input terminal exceeds the preset voltage, and outputs an overvoltage signal; the voltage comparison circuit outputs an off signal after receiving the overvoltage signal; the control circuit is in After receiving the disconnection signal, it outputs a disconnection signal to the switch circuit; after receiving the disconnection signal, the switch circuit disconnects the electrical connection between the positive input terminal and the positive output terminal, thereby disconnecting the positive input terminal in time
  • the electrical connection with the positive output terminal, the switching circuit, the voltage comparison circuit, the overvoltage detection circuit, and the control circuit are all pure hardware circuits. When the circuit is running, it is not easy to cause malfunctions, which improves the stability of overvoltage protection. Sex.
  • the over-voltage protection circuit of the present invention also includes a hysteresis circuit.
  • the hysteresis circuit controls the voltage comparison circuit to hysteresize and stop outputting the disconnection signal to avoid
  • the switching circuit is repeatedly electrically turned on and off in a short time, causing damage to the switching element.
  • the voltage comparison circuit of the present invention includes a stabilized voltage source, a comparator, a first resistor, a second resistor, a third resistor, and a fourth resistor.
  • the components of the voltage comparison circuit are pure hardware components, which are not easily damaged and increase overvoltage. The stability of the protection circuit, and the low price of components, reduces the cost of the overvoltage protection circuit.
  • the MOS tube of the present invention includes an N-type MOS tube, which has lower internal resistance, lower impact on the voltage of the positive output terminal, lower price than P-type MOS tube, and reduces the cost of the overvoltage protection circuit.
  • FIG. 1 is a schematic diagram of the circuit module structure of the overvoltage protection circuit of the present invention.
  • FIG. 2 is a schematic diagram of a specific circuit of an embodiment of the overvoltage protection circuit of the present invention.
  • FIG. 3 is a specific schematic diagram of the control circuit of the present invention.
  • FIG. 4 is a schematic circuit diagram of another embodiment of the overvoltage protection circuit of the present invention.
  • the present invention provides an overvoltage protection circuit 10, which is used to provide overvoltage protection for the positive terminal of an external circuit, for example, it can provide overvoltage protection for the positive pole of a booster pump.
  • the positive terminal includes a positive input terminal 20 and a positive output terminal 30.
  • the overvoltage protection circuit 10 is electrically connected to the positive input terminal 20 and the positive output terminal 30 respectively. When the voltage of the positive input terminal 20 does not reach the preset voltage, the overvoltage protection The circuit 10 electrically conducts between the positive input terminal 20 and the positive output terminal 30.
  • the overvoltage protection circuit 10 turns the positive The input terminal 20 and the positive output terminal 30 are electrically disconnected.
  • the overvoltage protection circuit 10 protects the positive pole, and can protect other electronic components in time to prevent burnout.
  • the positive input terminal 20 is a port for the positive input of an external circuit to input electric energy.
  • the positive input terminal 20 is an electrical node, such as a connection terminal, to be electrically connected to the outside.
  • the positive output terminal 30 is an electrical node, and electrical energy flows out from the positive output terminal 30 after passing through the positive input terminal 20.
  • the positive output terminal 30 is an electrical node, such as a connecting terminal, to be electrically connected to the outside. It can be understood that the positive input terminal 20 and the positive output terminal 30 can be omitted, and the overvoltage protection circuit 10 is directly electrically connected to an external circuit to control the electrical on/off of the external positive circuit.
  • the overvoltage protection circuit 10 includes an overvoltage detection circuit 11, a voltage comparison circuit 12, a control circuit 13 and a switch circuit 14.
  • the switch circuit 14 is electrically connected to the positive input terminal 20 and the positive output terminal 30, respectively.
  • the switch circuit 14 is used to control the electrical on and off between the positive input terminal 20 and the positive output terminal 30; the overvoltage detection circuit 11 and the positive The input terminal 20 is electrically connected.
  • the overvoltage detection circuit 11 is used to output an overvoltage signal when it detects that the voltage at the positive input terminal 20 exceeds the preset voltage; the voltage comparison circuit 12 and the overvoltage detection circuit 11 are electrically connected for voltage comparison
  • the circuit 12 is used to output a disconnection signal after receiving the overvoltage signal;
  • the control circuit 13 is electrically connected to the voltage comparison circuit 12 and the switch circuit 14 respectively, and the control circuit 13 is used to output the disconnection signal after receiving the disconnection signal
  • the signal is sent to the switch circuit 14; the switch circuit 14 is also used to disconnect the electrical connection between the positive input terminal 20 and the positive output terminal 30 after receiving the turn-off signal.
  • the overvoltage detection circuit 11 includes a first zener diode ZD1, the cathode of the first zener diode ZD1 is electrically connected to the positive input terminal 20, and the anode of the first zener diode ZD1 is electrically connected to the voltage comparison circuit 12 connection.
  • the voltage of the positive input terminal 20 does not reach the preset voltage, the electric energy of the positive input terminal 20 cannot pass through the first Zener diode ZD1.
  • the voltage at the positive input terminal 20 exceeds the preset voltage
  • the voltage at the positive input terminal 20 breaks down the Zener diode in the reverse direction, and the current at the anode input terminal 20 can flow through the first Zener diode ZD1 to the voltage comparison circuit 12, that is, the first Zener diode ZD1.
  • a Zener diode ZD1 outputs an overvoltage signal to the voltage comparison circuit 12.
  • the reverse breakdown voltage of the Zener diode is the preset voltage.
  • the reverse breakdown voltage of the first Zener diode ZD1 is not limited, and the first Zener diode ZD1 can be selected as required. Therefore, the model of the first Zener diode ZD1 is not limited, and the overvoltage protection voltage of the positive terminal is not limited.
  • the model of the first Zener diode ZD1 is BZX384-B16, and its reverse breakdown voltage is between 15.7V (volt, volt) ⁇ 16.3V, so the overvoltage protection voltage value of the positive terminal is at 15.7 Between V ⁇ 16.3V, that is, the preset voltage is between 15.7V ⁇ 16.3V.
  • the voltage comparison circuit 12 includes a voltage stabilizing source U1, a comparator U1A, a first voltage dividing element and a second voltage dividing element.
  • the output terminals of the voltage stabilizing source U1 are electrically connected to the first voltage dividing element and the second voltage dividing element, respectively.
  • the first voltage dividing element is also electrically connected to the reverse input terminal of the comparator U1A and the positive pole of the first Zener diode ZD1.
  • the first voltage dividing element is also grounded, and the second voltage dividing element is also in the same direction as the comparator U1A.
  • the input terminal is electrically connected, the second voltage dividing element is also grounded, and the output terminal of the comparator U1A is electrically connected to the control circuit 13.
  • the stabilized voltage source U1 can provide a stable voltage.
  • the voltage provided by the stabilized voltage source U1 is not limited. In this embodiment, the voltage provided by the stabilized voltage source U1 may be 2.5V.
  • the model of the voltage stabilizer U1 is not limited. The model of the stabilized voltage source can include TL341.
  • the first voltage dividing element includes a first resistor R1 and a second resistor R2.
  • the first end of the first resistor R1 is electrically connected to the output end of the stabilized voltage source U1, and the second end of the first resistor R1 is respectively connected to the second resistor R2.
  • the first terminal of the comparator U1A, the reverse input terminal of the comparator U1A, and the anode of the first Zener diode ZD1 are electrically connected, and the second terminal of the second resistor R2 is grounded.
  • the resistance of the first resistor R1 is 100 kohms
  • the resistance of the second resistor R2 is 10 kohms.
  • the second voltage dividing element includes a third resistor R3 and a fourth resistor R4.
  • the first end of the third resistor R3 is electrically connected to the output end of the voltage stabilizing source U1, and the second end of the third resistor R3 is connected to the fourth resistor R3.
  • the first end of the resistor R4 is electrically connected to the input end of the comparator U1A in the same direction, and the second end of the fourth resistor R4 is grounded.
  • the resistance of the third resistor R3 is 12 kiloohms
  • the resistance of the fourth resistor R4 is 10 kiloohms. It can be understood that the resistance can also be replaced by other elements to share the voltage, and the elements need only have a certain resistance value.
  • the ratio of the resistance of the first resistor R1 to the resistance of the second resistor R2 is greater than the ratio of the resistance of the third resistor R3 to the resistance of the fourth resistor R4, so that when the voltage at the positive input terminal 20 is not overvoltage, The voltage at the non-inverting input terminal of the comparator U1A is greater than the voltage at the reverse input terminal.
  • the voltage at the positive input terminal 20 is not overvoltage, the voltage at the second end of the first resistor R1 is 0.227V, and the voltage at the second end of the third resistor R3 is 1.136V, making the voltage at the non-inverting input end of the comparator U1A greater than the reverse The voltage at the input.
  • the model of comparator U1A is not limited.
  • the model of the comparator U1A is TP2271.
  • the voltage at the positive input terminal 20 is not overvoltage, the voltage at the non-inverting input terminal of the comparator U1A is greater than the voltage at the reverse input terminal, and the output terminal of the comparator U1A outputs a high-level voltage, that is, the output terminal of the comparator U1A outputs a conduction signal , Wherein the on-signal is a high-level signal.
  • the voltage at the reverse input terminal of the comparator U1A is equal to the voltage between the anode of the first Zener diode ZD1, so that the voltage at the non-inverting input terminal of the comparator U1A is less than that at the reverse input terminal.
  • the output terminal of the comparator U1A outputs a low-level voltage, that is, the output terminal of the comparator U1A outputs a disconnection signal, where the disconnection signal is a low-level signal. It can be understood that the comparator U1A needs to be provided with a working voltage, and a circuit for providing the working voltage is not described in this embodiment.
  • control circuit 13 outputs a turn-off signal to the switch circuit 14 after receiving the turn-off signal.
  • the control circuit 13 includes a control chip U2, and the model of the control chip U2 may be BQ76200.
  • the control chip U2 includes the following pins:
  • the first pin is used to receive the disconnection signal and the conduction signal.
  • the first pin is electrically connected to the output terminal of the comparator U1A.
  • the first pin can be the DSG_EN pin (pin 6).
  • the second pin the second pin outputs a shutdown signal when the first pin receives the disconnect signal.
  • the second pin outputs a turn-on signal when the first pin receives the turn-on signal.
  • the second pin is electrically connected to the switch circuit 14.
  • the shutdown signal is a low-level voltage. It can be understood that the model of the control chip U2 is not limited, as long as the same function can be realized.
  • the second pin can be a DSG pin (pin 12).
  • the switch circuit 14 includes a switch element.
  • the first end of the switch element is electrically connected to the positive input terminal 20, and the second end of the switch element is electrically connected to the positive output terminal 30.
  • the control terminal is electrically connected to the second pin of the control circuit 13.
  • the switching element can be a MOS tube or a triode. In this embodiment, the switching element is a MOS tube.
  • the drain of the MOS transistor Q1 is electrically connected to the positive input terminal 20, the source of the MOS transistor Q1 is electrically connected to the positive output terminal 30, and the gate of the MOS transistor Q1 is electrically connected to the control circuit. 13 Electrical connection.
  • the MOS tube Q1 includes an N-type MOS tube.
  • the gate of the MOS transistor Q1 When the gate of the MOS transistor Q1 receives a turn-on signal, that is, a high-level signal, the source and drain of the MOS transistor Q1 are electrically conducted, so that the positive input terminal 20 and the positive output terminal 30 are electrically connected. .
  • the gate of the MOS transistor Q1 receives a turn-off signal, that is, a low-level signal, the source and drain of the MOS transistor Q1 are electrically disconnected, so that the positive input terminal 20 and the positive output terminal 30 are electrically disconnected. open.
  • the model of the MOS tube Q1 is PSMN1R4-40YLD. The internal resistance of the N-type MOS tube is lower, the influence on the voltage of the positive output terminal 30 is lower, and the price is cheaper, which reduces the cost of the overvoltage protection circuit 10.
  • the first Zener diode ZD1 is not broken down, and the stabilized voltage source U1 provides voltage to the non-inverting input terminal and the reverse input terminal of the comparator U1A.
  • the voltage at the non-inverting input terminal of U1A is approximately 1.136V, and the voltage at the reverse input terminal of the comparator U1A is approximately 0.227V.
  • the voltage at the non-inverting input terminal of U1A is greater than the voltage at the reverse input terminal, and the output terminal of the comparator U1A outputs high voltage. If the control chip U2 does not output a turn-off signal, the source and drain of the MOS transistor Q1 are electrically conducted.
  • the first zener diode ZD1 When the voltage of the positive input terminal 20 exceeds the preset voltage, the first zener diode ZD1 is broken down, the positive input terminal 20 provides voltage to the reverse input terminal of the comparator U1A, and the stabilized voltage source U1 provides the same direction input of the comparator U1A
  • the voltage at the same direction input terminal of U1A is less than the voltage at the reverse input terminal, the output terminal of the comparator U1A outputs a low level, the control chip U2 outputs a shutdown signal, and the source and drain of the MOS transistor Q1 are electrically disconnected , Protect the safety of the electronic components connected after the positive output terminal 30 to prevent burning.
  • the overvoltage protection circuit 10 also includes a hysteresis circuit 15, the hysteresis circuit 15 and the voltage comparison circuit 12 are electrically connected, the hysteresis circuit 15 is used for the positive input terminal 20 voltage by When the voltage greater than the preset voltage becomes equal to the preset voltage, the control voltage comparison circuit 12 hysteresis and stops outputting the disconnect signal.
  • the hysteresis circuit 15 includes a third voltage dividing element and a first diode D1.
  • the anode of the first diode D1 is electrically connected to the same direction input terminal of the comparator U1A, and the cathode of the first diode D1 is respectively connected to the comparator U1A.
  • the output terminal of U1A is electrically connected to the third voltage dividing element, the third voltage dividing element is also electrically connected to the control circuit 13, and the third voltage dividing element is also grounded.
  • the third voltage dividing element includes a resistor R5 and a resistor R6.
  • the first end of the resistor R5 is electrically connected to the cathode of the first diode D1 and the output end of the comparator U1A.
  • the second end of the resistor R5 is respectively connected to the control circuit 13
  • the first pin of the control chip U2 and the first end of the resistor R6 are electrically connected, and the second end of the resistor R6 is grounded.
  • the resistance value of the resistor R5 is 100 kiloohms
  • the resistance value of the resistor R6 is 100 kiloohms.
  • the model of the first diode D1 is 1N4148WS.
  • the hysteresis circuit 15 further includes a fourth voltage dividing element, the first end of the fourth voltage dividing element is electrically connected to the same direction input end of the comparator U1A, and the second end of the fourth voltage dividing element is electrically connected to the The anode of the first diode D1 is electrically connected.
  • the fourth voltage dividing element may be a resistor.
  • the fourth voltage dividing element is a resistor R7, and the resistance value of the resistor R7 is 100 kiloohms.
  • the output terminal of the comparator U1A When the voltage of the positive input terminal 20 is lower than the preset voltage, the voltage of the same direction input terminal of U1A is greater than the voltage of the reverse input terminal, the output terminal of the comparator U1A outputs a high level, the first diode D1 will not conduct, and the current It will not flow from the resistor R7, the first diode D1, the resistor R5, and the resistor R6 to the ground in sequence.
  • the output terminal of the comparator U1A When the voltage of the positive input terminal 20 exceeds the preset voltage, the voltage at the non-inverting input terminal of U1A is less than the voltage at the reverse input terminal, the output terminal of the comparator U1A outputs a low level, the first diode D1 is turned on, and the current will change from The resistor R7, the first diode D1, the resistor R5, and the resistor R6 flow to the ground terminal, so that the hysteresis circuit 15 and the fourth resistor R4 are connected in parallel.
  • the first Zener diode ZD1 When the voltage at the positive input terminal 20 changes from exceeding the preset voltage to the critical preset voltage, the first Zener diode ZD1 is not broken down, and the stabilizer source U1 supplies the first resistor R1, the second resistor R2, and the third resistor R3.
  • the fourth resistor R4 provides a voltage.
  • the hysteresis circuit 15 is still connected in parallel with the fourth resistor R4.
  • the voltage at the first terminal of the fourth resistor R4 and the voltage at the same-inverting input terminal of the comparator U1A become lower, lower than 1.136V.
  • the output level of the output terminal of the comparator U1A is lower than the turn-on signal, that is, the hysteresis stops outputting the turn-off signal, and the switching element will not turn on.
  • the output level of the output terminal of the comparator U1A is high, the first diode D1 will be reversely blocked, and the hysteresis circuit 15 is no longer connected in parallel with the fourth resistor R4, so that the voltage at the first end of the fourth resistor R4 is compared with
  • the voltage at the non-inverting input terminal of the U1A is equal to 1.136V, and the output level of the output terminal of the comparator U1A is a conduction signal, and the switching element is turned on.
  • the hysteresis circuit 15 causes the switching element to be turned on with a hysteresis time.
  • the switching element is repeatedly electrically conducted and electrically disconnected in a short time, causing damage to the switching element.
  • the hysteresis circuit 15 further includes a second Zener diode ZD2, the anode of the second Zener diode ZD2 is grounded, and the cathode of the second Zener diode ZD2 is electrically connected to the second end of the resistor R5.
  • the model of the second Zener diode ZD2 is BZX384-B12.
  • the voltage comparison circuit 12 further includes a second diode D2, a resistor R8, a resistor R9, a third Zener diode ZD3, and a capacitor C1.
  • the anode of the second diode D2 is electrically connected to the anode input terminal 20
  • the cathode of the earphone tube D2 is electrically connected to the first end of the resistor R8, and the second end of the resistor R8 is electrically connected to the first end and the third end of the resistor R9.
  • the cathode of the Zener diode ZD3, the first end of the capacitor C1, and the positive power end of the comparator U1A are electrically connected, the second end of the resistor R9 is electrically connected to the output end of the voltage stabilizer U1, and the third Zener diode ZD3
  • the positive pole is grounded, and the second end of the capacitor C1 is grounded.
  • a stable working voltage is provided to the comparator U1A, which makes the output voltage of the stabilized voltage source U1 more stable.
  • the model of the second diode D2 is 1N4148WS; the resistance of the resistor R8 is 2.2 kohms, and the resistance of the resistor R9 is 20 kohms; the model of the third Zener diode ZD3 is BZX384-B16; the capacitor C1
  • the capacity is 0.1 ⁇ F (micro method).
  • the voltage comparison circuit 12 further includes a capacitor C2.
  • the first terminal of the capacitor C2 is electrically connected to the same direction input terminal of the comparator U1A, and the second terminal of the capacitor C2 is grounded.
  • the capacitor C2 is used for filtering, and the voltage provided by the non-inverting input terminal of the comparator U1A is more stable.
  • the capacitance of the capacitor C2 is 0.1 ⁇ F.
  • the overvoltage detection circuit 11 also includes a first resistor R10.
  • the first end of the first resistor R10 is electrically connected to the anode of the first Zener diode ZD1, and the second end of the capacitor R10 is respectively connected to the second end of the first resistor R1,
  • the non-inverting input terminal of the comparator U1A is electrically connected.
  • the first resistor R10 divides the voltage so that when the first Zener diode ZD1 is reversely broken down, the voltage provided to the same direction input terminal of the comparator U1A is more suitable.
  • the resistance of the first resistor R10 is 1 kiloohm.
  • the switch circuit 14 further includes a first resistor R11.
  • the first end of the first resistor R11 is electrically connected to the second pin of the control chip U2, and the second end of the first resistor R11 is electrically connected to the control end of the switching element.
  • the first resistor R11 shares the voltage, so that the voltage provided by the second pin of the control chip U2 to the switching element is more suitable.
  • the resistance of the first resistor R11 is 1 kiloohm.
  • the switching circuit 14 further includes a first resistor R12.
  • the first end of the first resistor R12 is electrically connected to the control end of the switching element.
  • the second end of the first resistor R12 is electrically connected to the second end of the switching element and the positive output terminal 30 respectively. Sexual connection.
  • the resistance of the first resistor R12 is 10 megaohms.
  • the switching circuit 14 also includes a fourth Zener diode ZD4.
  • the anode of the fourth Zener diode ZD4 is electrically connected to the second end and the anode output end 30 of the switching element, respectively.
  • the cathode of the fourth Zener diode ZD4 is electrically connected to the control of the switching element.
  • the terminals are electrically connected.
  • the model of the fourth Zener diode ZD4 is BZX384-B16.
  • the overvoltage detection circuit of the present invention detects that the voltage at the positive input terminal exceeds the preset voltage, and outputs an overvoltage signal; the voltage comparison circuit outputs an off signal after receiving the overvoltage signal; the control circuit is in After receiving the disconnection signal, it outputs a disconnection signal to the switch circuit; after receiving the disconnection signal, the switch circuit disconnects the electrical connection between the positive input terminal and the positive output terminal, thereby disconnecting the positive input terminal in time
  • the electrical connection with the positive output terminal, the switching circuit, the voltage comparison circuit, the overvoltage detection circuit, and the control circuit are all pure hardware circuits. When the circuit is running, it is not easy to cause malfunctions, which improves the stability of overvoltage protection. Sex.
  • the over-voltage protection circuit of the present invention also includes a hysteresis circuit.
  • the hysteresis circuit controls the voltage comparison circuit to hysteresize and stop outputting the disconnection signal to avoid
  • the switching circuit is repeatedly electrically turned on and off in a short time, causing damage to the switching element.
  • the voltage comparison circuit of the present invention includes a stabilized voltage source, a comparator, a first resistor, a second resistor, a third resistor, and a fourth resistor.
  • the components of the voltage comparison circuit are pure hardware components, and the overvoltage protection circuit is added. Stability, more common components and low prices, reducing the cost of overvoltage protection circuits.
  • the MOS tube of the present invention includes an N-type MOS tube, which has lower internal resistance, lower impact on the voltage of the positive output terminal, lower price than P-type MOS tube, and reduces the cost of the overvoltage protection circuit.

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Abstract

本发明公开了一种过压保护电路，过压保护电路包括：开关电路，开关电路分别和正极输入端、正极输出端电性连接，开关电路用于控制正极输入端和正极输出端之间的电性通断；过压检测电路，过压检测电路和正极输入端电性连接，过压检测电路用于检测到正极输入端的电压超过预设电压时，输出过压信号；电压比较电路，电压比较电路和过压检测电路电性连接，电压比较电路用于在接收到过压信号后，输出断开信号；控制电路，控制电路分别和电压比较电路、开关电路电性连接，控制电路用于在接收到断开信号后，输出关断信号给开关电路；开关电路还用于接收到关断信号后断开正极输入端和正极输出端之间的电性连接。该过压保护电路的稳定性较高。

Description

过压保护电路
本申请要求于2019年5月24日提交中国专利局、申请号为201910441339.8、申请名称为“过压保护电路”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电路保护领域，尤其涉及一种过压保护电路。
背景技术
电路设计的时候一般会对供电电路做一些过压的保护，合理的电路设计可以避免产品遭到损坏，延长产品使用寿命等。针对要求比较高的应用，恰当的电路设计对电路至关重要。一些电路应用中，使用的电流很大，电压很高，常规的负极端保护电路往往会因为关断的不够及时，而烧毁器件。而现有的过压保护多为程序控制的方式，会出现程序跑飞，栓锁等程序故障，过压保护的稳定性过低。
因此如何提高一种稳定性高的过压保护方式，就成了现有技术的需求。
发明内容
本发明的主要目的在于提供一种过压保护电路，旨在解决现有的过压保护的稳定性低的技术问题。
为实现上述目的，本发明提供的一种过压保护电路，用于给外部电路的正极输入端和正极输出端之间提供过压保护，所述过压保护电路包括：
开关电路，所述开关电路分别和所述正极输入端、所述正极输出端电性连接，所述开关电路用于控制所述正极输入端和所述正极输出端之间的电性通断；
过压检测电路，所述过压检测电路和所述正极输入端电性连接，所述过压检测电路用于检测到所述正极输入端的电压超过预设电压时，输出过压信号；
电压比较电路，所述电压比较电路和所述过压检测电路电性连接，所述电压比较电路用于在接收到所述过压信号后，输出断开信号；以及
控制电路，所述控制电路分别和所述电压比较电路、所述开关电路电性连接，所述控制电路用于在接收到所述断开信号后，输出关断信号给所述开关电路；
所述开关电路还用于接收到所述关断信号后断开所述正极输入端和所述正极输出端之间的电性连接。
优选地，所述过压保护电路还包括迟滞电路，所述迟滞电路和所述电压比较电路电性连接，所述迟滞电路用于在所述正极输入端的电压由大于所述预设 电压变为等于所述预设电压时，控制所述电压比较电路迟滞停止输出所述断开信号。
优选地，所述电压比较电路包括稳压源、比较器、第一分压元件和第二分压元件，所述稳压源的输出端分别和所述第一分压元件、所述第二分压元件电性连接，所述第一分压元件分别和所述比较器的反向输入端、所述过压检测电路电性连接，所述第二分压元件和所述比较器的同向输入端电性连接，所述比较器的输出端和所述控制电路电性连接。
优选地，所述第一分压元件包括第一电阻和第二电阻，所述第一电阻的第一端和所述稳压源的输出端电性连接，所述第一电阻的第二端分别和所述第二电阻的第一端、所述比较器的反向输入端、所述过压检测电路电性连接，所述第二电阻的第二端接地；所述第二分压元件包括第三电阻和第四电阻，所述第三电阻的第一端和所述稳压源的输出端电性连接，所述第三电阻的第二端分别和所述第四电阻的第一端、所述比较器的同向输入端电性连接，所述第四电阻的第二端接地。
优选地，所述第一电阻的阻值与所述第二电阻的阻值之比大于所述第三电阻的阻值与所述第四电阻的阻值之比。
优选地，所述过压保护电路还包括迟滞电路，所述迟滞电路包括第三分压元件和第一二极管，所述第一二极管的正极和比较器的同向输入端电性连接，所述第一二极管的负极分别和所述比较器的输出端、所述第三分压元件电性连接，所述第三分压元件还和所述控制电路电性连接，第三分压元件还接地。
优选地，所述过压检测电路包括第一稳压二极管，所述第一稳压二极管的负极和所述正极输入端电性连接，所述第一稳压二极管的正极和所述比较器的反向输入端电性连接。
优选地，所述控制电路包括控制芯片，所述控制芯片包括第一管脚和第二管脚，所述比较器的输出端和控制芯片的第一管脚电性连接，所述控制芯片的第二管脚和所述开关电路电性连接。
优选地，所述开关电路包括MOS管，所述MOS管的漏极和所述正极输入端电性连接，所述MOS管的源极和所述正极输出端电性连接，所述MOS管的栅极和所述控制电路电性连接。
优选地，所述MOS管包括N型MOS管。
与现有技术相比，本发明的过压检测电路检测到正极输入端的电压超过预设电压时，输出过压信号；电压比较电路在接收到过压信号后，输出断开信号；控制电路在接收到断开信号后，输出关断信号给所述开关电路；开关电路接收到关断信号后断开正极输入端和所述正极输出端之间的电性连接，从而及时断开正极输入端和所述正极输出端之间的电性连接，开关电路、电压比较电路、过压检测电路和控制电路都为纯硬件的电路，在电路运行时，不易产生故障，提高了过压保护的稳定性。
本发明的过压保护电路还包括迟滞电路，迟滞电路在所述正极输入端的电 压由大于所述预设电压变为等于所述预设电压时，控制电压比较电路迟滞停止输出断开信号，避免了电压临界预设电压时，开关电路短时间内反复电性导通和电性断开，对开关元件造成损害。
本发明的电压比较电路包括稳压源、比较器、第一电阻、第二电阻、第三电阻和第四电阻，电压比较电路的元件都为纯硬件的元器件，不易损坏，增加了过压保护电路的稳定性，且元器件价格便宜，降低了过压保护电路的成本。
本发明的MOS管包括N型MOS管，内阻更低，对正极输出端的电压影响较低，价格比P型MOS管更低，降低了过压保护电路的成本。
附图说明
图1为本发明的过压保护电路的电路模块结构示意图；
图2为本发明的过压保护电路一实施例的具体电路示意图；
图3为本发明的控制电路的具体示意图；
图4为本发明的过压保护电路另一实施例的具体电路示意图。
本发明目的的实现、功能特点及优点将结合实施例，参照附图做进一步说明。
具体实施方式
为了使本发明的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本发明进行进一步详细说明。应当理解，此处所描述的具体实施例仅用以解释本发明，并不用于限定本发明。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
本申请的说明书和权利要求书及上述附图中的术语“第一”、“第二”、“第三”、“第四”等(如果存在)是用于区别类似的对象，而不必用于描述特定的顺序或先后次序。应该理解这样使用的数据在适当情况下可以互换，以便这里描述的实施例能够以除了在这里图示或描述的内容以外的顺序实施。此外，术语“包括”和“具有”以及他们的任何变形，意图在于覆盖不排他的包含，例如，包含了一系列步骤或单元的过程、方法、系统、产品或设备不必限于清楚地列出的那些步骤或单元，而是可包括没有清楚地列出的或对于这些过程、方法、产品或设备固有的其它步骤或单元。
需要说明的是，在本发明中涉及“第一”、“第二”等的描述仅用于描述目的，而不能理解为指示或暗示其相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”的特征可以明示或者隐含地包括至少一个该特征。另外，各个实施例之间的技术方案可以相互结合，但是必须是以本领域普通技术人员能够实现为基础，当技术方案的结合出现相互矛盾或无法实 现时应当认为这种技术方案的结合不存在，也不在本发明要求的保护范围之内。
请参阅图1，本发明提供一种过压保护电路10，其用于给外部电路的正极端提供过压保护，如可以给升压泵的正极提供过压保护。正极端包括正极输入端20和正极输出端30，过压保护电路10分别和正极输入端20和正极输出端30电性连接，在正极输入端20的电压没有达到预设电压时，过压保护电路10把正极输入端20和正极输出端30之间电性导通，在正极输入端20的电压超过预设电压时，即正极输入端20的电压过压时，过压保护电路10把正极输入端20和正极输出端30之间电性断开。过压保护电路10保护正极端，能及时对其他电子元器件进行保护，防止烧毁。
正极输入端20为外部电路的正极输入电能的端口。正极输入端20为电性的节点，如可以为接线端子，以和外部电性连接。
正极输出端30为电性的节点，电能经正极输入端20后，从正极输出端30流出。正极输出端30为电性的节点，如可以为接线端子，以和外部电性连接。可以理解，正极输入端20和正极输出端30可以省略，过压保护电路10直接和外部的电路电性连接，以控制外部的正极电路的电性通断。
过压保护电路10包括过压检测电路11、电压比较电路12、控制电路13和开关电路14。开关电路14分别和正极输入端20、所述正极输出端30电性连接，开关电路14用于控制正极输入端20和正极输出端30之间的电性通断；过压检测电路11和正极输入端20电性连接，过压检测电路11用于在检测到正极输入端20的电压超过预设电压时，输出过压信号；电压比较电路12和过压检测电路11电性连接，电压比较电路12用于在接收到过压信号后，输出断开信号；控制电路13分别和电压比较电路12、开关电路14电性连接，控制电路13用于在接收到断开信号后，输出关断信号给开关电路14；开关电路14还用于接收到关断信号后断开正极输入端20和正极输出端30之间的电性连接。
请参阅图2，过压检测电路11包括第一稳压二极管ZD1，第一稳压二极管ZD1的负极和正极输入端20电性连接，第一稳压二极管ZD1的正极和电压比较电路12电性连接。在正极输入端20的电压未达到预设电压时，正极输入端20的电能不能通过第一稳压二极管ZD1。在正极输入端20的电压超出预设电压时，正极输入端20的电压把稳压二极管反向击穿，正极输入端20的电流能经过第一稳压二极管ZD1流向电压比较电路12，即第一稳压二极管ZD1输出过压信号给电压比较电路12。稳压二极管的反向击穿电压为预设电压。第一稳压二极管ZD1的反向击穿电压不做限定，可根据需要进行选择第一稳压二极管ZD1。故第一稳压二极管ZD1的型号也不做限定，正极端的过压保护电压也不做限定。在本实施例中，第一稳压二极管ZD1的型号为BZX384-B16，其反向击穿电压在15.7V(volt，伏特)～16.3V之间，所以正极端的过压保护电压 值位于15.7V～16.3V之间，即预设电压位于15.7V～16.3V之间。
电压比较电路12包括稳压源U1、比较器U1A、第一分压元件和第二分压元件，稳压源U1的输出端分别和第一分压元件、第二分压元件电性连接，第一分压元件还分别和比较器U1A的反向输入端、第一稳压二极管ZD1的正极电性连接，第一分压元件还接地，第二分压元件还和比较器U1A的同向输入端电性连接，第二分压元件还接地，比较器U1A的输出端和控制电路13电性连接。
稳压源U1能提供稳定的电压。稳压源U1提供电压的大小不做限定。在本实施例中，稳压源U1提供的电压可以为2.5V。稳压源U1的型号不做限定。稳压源的型号可以包括TL341。
第一分压元件包括第一电阻R1和第二电阻R2，第一电阻R1的第一端和稳压源U1的输出端电性连接，第一电阻R1的第二端分别和第二电阻R2的第一端、比较器U1A的反向输入端、第一稳压二极管ZD1的正极电性连接，第二电阻R2的第二端接地。第一电阻R1的阻值为100千欧，第二电阻R2的阻值为10千欧。
第二分压元件包括第三电阻R3和第四电阻R4，第三电阻R3的第一端和稳压源U1的输出端电性连接，第三电阻R3的第二端分别和所述第四电阻R4的第一端、比较器U1A的同向输入端电性连接，第四电阻R4的第二端接地。第三电阻R3的阻值为12千欧，第四电阻R4的阻值为10千欧。可以理解，电阻可也以用其他元件替代，以分担电压，元件具有一定的阻值即可。其中，第一电阻R1的阻值与第二电阻R2的阻值之比大于第三电阻R3的阻值与第四电阻R4的阻值之比，使正极输入端20的电压没有过压时，比较器U1A的同向输入端的电压大于反向输入端的电压。正极输入端20的电压没有过压时，第一电阻R1的第二端的电压为0.227V，第三电阻R3的第二端的电压为1.136V，使比较器U1A的同向输入端的电压大于反向输入端的电压。
比较器U1A的型号不做限定。在本实施例中，比较器U1A的型号为TP2271。正极输入端20的电压没有过压时，比较器U1A的同向输入端的电压大于反向输入端的电压，比较器U1A的输出端输出高电平电压，即比较器U1A的输出端输出导通信号，其中，所述导通信号为高电平信号。在正极输入端20的电压超出预设电压时，比较器U1A的反向输入端的电压等于第一稳压二极管ZD1正极之间的电压，使比较器U1A的同向输入端的电压小于反向输入端的电压，比较器U1A的输出端输出低电平电压，即比较器U1A的输出端输出断开信号，其中，所述断开信号为低电平信号。可以理解，需要给比较器U1A提供工作电压，提供工作电压的电路，本实施例不再进行说明。
请参阅图3，控制电路13在接收到断开信号后，输出关断信号给开关电路14。控制电路13包括控制芯片U2，控制芯片U2的型号可以为BQ76200。控制芯片U2包括下列管脚：
第一管脚：第一管脚用于接收断开信号和导通信号。第一管脚和比较器U1A的输出端电性连接。第一管脚可以为DSG_EN管脚(6号管脚)。
第二管脚：第二管脚在第一管脚接收到断开信号时，输出关断信号。第二管脚在第一管脚接收到导通信号时，输出开启信号。第二管脚和开关电路14电性连接。关断信号为低电平电压。可以理解，控制芯片U2的型号不做限定，能实现相同的功能即可。第二管脚可以为DSG管脚(12号管脚)。
请一并参阅图2和图3，开关电路14包括开关元件，开关元件的第一端和正极输入端20电性连接，开关元件的第二端和正极输出端30电性连接，开关元件的控制端和控制电路13的第二管脚电性连接。开关元件可以为MOS管或三极管。在本实施例中，开关元件为MOS管。即为图中的MOS管Q1，MOS管Q1的漏极和正极输入端20电性连接，所述MOS管Q1的源极和正极输出端30电性连接，MOS管Q1的栅极和控制电路13电性连接。其中，MOS管Q1包括N型MOS管。MOS管Q1的栅极在接收到开启信号时，即高电平信号时，MOS管Q1的源极和漏极电性导通，使正极输入端20和正极输出端30之间电性导通。MOS管Q1的栅极在接收到关断信号时，即低电平信号时，MOS管Q1的源极和漏极电性断开，使正极输入端20和正极输出端30之间电性断开。本实施例中，MOS管Q1的型号为PSMN1R4-40YLD。N型MOS管的内阻更低，对正极输出端30的电压影响较低，价格更便宜，降低了过压保护电路10的成本。
在使用时，正极输入端20的电压低于预设电压时，第一稳压二极管ZD1未被击穿，稳压源U1给比较器U1A的同向输入端和反向输入端提供电压，比较器U1A的同向输入端电压约为1.136V，比较器U1A的反向输入端电压约为0.227V，U1A的同向输入端电压大于反向输入端电压，比较器U1A的输出端输出高电平，控制芯片U2不会输出关断信号，MOS管Q1的源极和漏极电性导通。正极输入端20的电压超过预设电压时，第一稳压二极管ZD1被击穿，正极输入端20给比较器U1A的反向输入端提供电压，稳压源U1给比较器U1A的同向输入端提供电压，U1A的同向输入端电压小于反向输入端电压，比较器U1A的输出端输出低电平，控制芯片U2输出关断信号，MOS管Q1的源极和漏极电性断开，保护正极输出端30之后连接的电子元器件的安全，防止烧毁。
请继续参阅图3，过压保护电路10还包括迟滞电路15，所述迟滞电路15和所述电压比较电路12电性连接，所述迟滞电路15用于在所述正极输入端20的电压由大于所述预设电压变为等于所述预设电压时，控制电压比较电路12迟滞停止输出断开信号。
迟滞电路15包括第三分压元件和第一二极管D1，第一二极管D1的正极和比较器U1A的同向输入端电性连接，第一二极管D1的负极分别和比较器U1A的输出端、第三分压元件电性连接，第三分压元件还和控制电路13电性连接，第三分压元件还接地。
第三分压元件包括电阻R5和电阻R6，电阻R5的第一端分别和第一二极管D1的负极、比较器U1A的输出端电性连接，电阻R5的第二端分别和控制电路13的控制芯片U2的第一管脚、电阻R6的第一端电性连接，电阻R6的第二端接地。电阻R5的阻值为100千欧，电阻R6的阻值为100千欧。
第一二极管D1的型号是1N4148WS。
作为一种实施方式，迟滞电路15包括还包括第四分压元件，第四分压元件的第一端和比较器U1A的同向输入端电性连接，第四分压元件的第二端和第一二极管D1的正极电性连接。第四分压元件可以是电阻，在本实施例中，第四分压元件为电阻R7，电阻R7的阻值为100千欧。
正极输入端20的电压低于预设电压时，U1A的同向输入端电压大于反向输入端电压，比较器U1A的输出端输出高电平，第一二极管D1不会导通，电流不会依次从电阻R7、第一二极管D1、电阻R5、电阻R6流向接地端。正极输入端20的电压超出预设电压时，U1A的同向输入端电压小于反向输入端电压，比较器U1A的输出端输出低电平，第一二极管D1导通，电流会依次从电阻R7、第一二极管D1、电阻R5、电阻R6流向接地端，使迟滞电路15和第四电阻R4并联。在正极输入端20的电压由超出预设电压变为临界预设电压时，第一稳压二极管ZD1未被击穿，稳压源U1给第一电阻R1、第二电阻R2、第三电阻R3、第四电阻R4提供电压，此时迟滞电路15依旧和第四电阻R4并联，第四电阻R4第一端的电压、比较器U1A的同向输入端的电压变低，低于1.136V。比较器U1A的输出端输出的电平低于导通信号，即迟滞停止输出断开信号，开关元件不会导通。比较器U1A的输出端输出的电平为高电平，第一二极管D1会反向截止，迟滞电路15不再和第四电阻R4并联，使第四电阻R4第一端的电压、比较器U1A的同向输入端的电压等于1.136V，比较器U1A的输出端输出的电平为导通信号，开关元件才会导通。迟滞电路15使开关元件的导通有一个迟滞时间。不会使正极输入端20的电压临界预设电压时，开关元件短时间内反复电性导通和电性断开，对开关元件造成损害。
作为一种实施方式，迟滞电路15包括还包括第二稳压二极管ZD2，第二稳压二极管ZD2的正极接地，第二稳压二极管ZD2的负极和电阻R5的第二端电性连接。第二稳压二极管ZD2的型号是BZX384-B12。
请参阅图4，在一实施例中，电压比较电路12还包括第二二极管D2、电阻R8、电阻R9、第三稳压二极管ZD3和电容C1。第二二极管D2的正极和正极输入端20电性连接，耳机管D2的负极和电阻R8的第一端电性连接，电阻R8的第二端分别和电阻R9的第一端、第三稳压二极管ZD3的负极、电容C1的第一端、比较器U1A的正电源端电性连接，电阻R9的第二端和稳压源U1的输出端电性连接，第三稳压二极管ZD3的正极接地，电容C1的第二端接地。给比较器U1A提供了稳定的工作电压，使稳压源U1的输出电压更加稳定。其中，第二二极管D2的型号是1N4148WS；电阻R8的阻值为2.2千欧，电阻R9的阻值为20千欧；第三稳压二极管ZD3的型号为BZX384-B16；电容C1的电容量为0.1μF(微法)。
电压比较电路12还包括电容C2，电容C2的第一端和比较器U1A的同向输入端电性连接，电容C2的第二端接地。电容C2用于滤波，比较器U1A的同相输入端提供的电压更加稳定。电容C2的电容量为0.1μF。
过压检测电路11还包括第一电阻R10，第一电阻R10的第一端和第一稳压二极管ZD1的正极电性连接，电容R10的第二端分别和第一电阻R1的第二端、比较器U1A的同向输入端电性连接。第一电阻R10进行分压，使在第一稳压二极管ZD1被反向击穿时，给比较器U1A的同向输入端提供的电压更加合适。第一电阻R10阻值为1千欧。
开关电路14还包括第一电阻R11，第一电阻R11的第一端和控制芯片U2的第二管脚电性连接，第一电阻R11的第二端和开关元件的控制端电性连接。第一电阻R11分担电压，使控制芯片U2的第二管脚给开关元件提供的电压更加合适。第一电阻R11的阻值为1千欧。
开关电路14还包括第一电阻R12，第一电阻R12的第一端和开关元件的控制端电性连接，第一电阻R12的第二端分别和开关元件的第二端、正极输出端30电性连接。第一电阻R12的阻值为10兆欧。
开关电路14还包括第四稳压二极管ZD4，第四稳压二极管ZD4的正极分别和开关元件的第二端、正极输出端30电性连接，第四稳压二极管ZD4的负极和开关元件的控制端电性连接。第四稳压二极管ZD4的型号为BZX384-B16。
与现有技术相比，本发明的过压检测电路检测到正极输入端的电压超过预设电压时，输出过压信号；电压比较电路在接收到过压信号后，输出断开信号；控制电路在接收到断开信号后，输出关断信号给所述开关电路；开关电路接收到关断信号后断开正极输入端和所述正极输出端之间的电性连接，从而及时断开正极输入端和所述正极输出端之间的电性连接，开关电路、电压比较电路、过压检测电路和控制电路都为纯硬件的电路，在电路运行时，不易产生故障，提高了过压保护的稳定性。
本发明的过压保护电路还包括迟滞电路，迟滞电路在所述正极输入端的电压由大于所述预设电压变为等于所述预设电压时，控制电压比较电路迟滞停止输出断开信号，避免了电压临界预设电压时，开关电路短时间内反复电性导通和电性断开，对开关元件造成损害。
本发明的电压比较电路包括稳压源、比较器、第一电阻、第二电阻、第三电阻和第四电阻，电压比较电路的元件都为纯硬件的元器件，增加了过压保护电路的稳定性，且元器件较为常见，价格便宜，降低了过压保护电路的成本。
本发明的MOS管包括N型MOS管，内阻更低，对正极输出端的电压影响较低，价格比P型MOS管更低，降低了过压保护电路的成本。
需要说明的是，上述本发明实施例序号仅仅为了描述，不代表实施例的优劣。并且本文中的术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要素的过程、装置、物品或者方法不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种过程、装置、物品或者方法所固有的要素。在没有更多限制的情况下，由语句“包括一个……”限定的要素，并不排除在包括该要素的过程、装置、物品或者方法中 还存在另外的相同要素。
以上仅为本发明的优选实施例，并非因此限制本发明的专利范围，凡是利用本发明说明书及附图内容所作的等效结构或等效流程变换，或直接或间接运用在其他相关的技术领域，均同理包括在本发明的专利保护范围内。

Claims (10)

  1. 一种过压保护电路，用于给外部电路的正极输入端和正极输出端之间提供过压保护，其特征在于，所述过压保护电路包括：
    开关电路，所述开关电路分别和所述正极输入端、所述正极输出端电性连接，所述开关电路用于控制所述正极输入端和所述正极输出端之间的电性通断；
    过压检测电路，所述过压检测电路和所述正极输入端电性连接，所述过压检测电路用于检测到所述正极输入端的电压超过预设电压时，输出过压信号；
    电压比较电路，所述电压比较电路和所述过压检测电路电性连接，所述电压比较电路用于在接收到所述过压信号后，输出断开信号；以及
    控制电路，所述控制电路分别和所述电压比较电路、所述开关电路电性连接，所述控制电路用于在接收到所述断开信号后，输出关断信号给所述开关电路；
    所述开关电路还用于接收到所述关断信号后断开所述正极输入端和所述正极输出端之间的电性连接。
  2. 如权利要求1所述的过压保护电路，其特征在于：所述过压保护电路还包括迟滞电路，所述迟滞电路和所述电压比较电路电性连接，所述迟滞电路用于在所述正极输入端的电压由大于所述预设电压变为等于所述预设电压时，控制所述电压比较电路迟滞停止输出所述断开信号。
  3. 如权利要求1所述的过压保护电路，其特征在于：所述电压比较电路包括稳压源、比较器、第一分压元件和第二分压元件，所述稳压源的输出端分别和所述第一分压元件、所述第二分压元件电性连接，所述第一分压元件分别和所述比较器的反向输入端、所述过压检测电路电性连接，所述第二分压元件和所述比较器的同向输入端电性连接，所述比较器的输出端和所述控制电路电性连接。
  4. 如权利要求3所述的过压保护电路，其特征在于：所述第一分压元件包括第一电阻和第二电阻，所述第一电阻的第一端和所述稳压源的输出端电性连接，所述第一电阻的第二端分别和所述第二电阻的第一端、所述比较器的反向输入端、所述过压检测电路电性连接，所述第二电阻的第二端接地；所述第二分压元件包括第三电阻和第四电阻，所述第三电阻的第一端和所述稳压源的输出端电性连接，所述第三电阻的第二端分别和所述第四电阻的第一端、所述比较器的同向输入端电性连接，所述第四电阻的第二端接地。
  5. 如权利要求4所述的过压保护电路，其特征在于：所述第一电阻的阻值与所述第二电阻的阻值之比大于所述第三电阻的阻值与所述第四电阻的阻值之比。
  6. 如权利要求3所述的过压保护电路，其特征在于：所述过压保护电路还包括迟滞电路，所述迟滞电路包括第三分压元件和第一二极管，所述第一二 极管的正极和比较器的同向输入端电性连接，所述第一二极管的负极分别和所述比较器的输出端、所述第三分压元件电性连接，所述第三分压元件还和所述控制电路电性连接，第三分压元件还接地。
  7. 如权利要求3所述的过压保护电路，其特征在于：所述过压检测电路包括第一稳压二极管，所述第一稳压二极管的负极和所述正极输入端电性连接，所述第一稳压二极管的正极和所述比较器的反向输入端电性连接。
  8. 如权利要求3所述的过压保护电路，其特征在于：所述控制电路包括控制芯片，所述控制芯片包括第一管脚和第二管脚，所述比较器的输出端和控制芯片的第一管脚电性连接，所述控制芯片的第二管脚和所述开关电路电性连接。
  9. 如权利要求3所述的过压保护电路，其特征在于：所述开关电路包括MOS管，所述MOS管的漏极和所述正极输入端电性连接，所述MOS管的源极和所述正极输出端电性连接，所述MOS管的栅极和所述控制电路电性连接。
  10. 如权利要求9所述的过压保护电路，其特征在于：所述MOS管包括N型MOS管。
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