Direct-current power supply input protection circuit

Abstract

The utility model discloses a DC power supply input protection circuit. The transient absorption circuit is used for absorbing transient voltage spike pulse generated by input voltage of the power supply; the voltage stabilizing circuit is used for generating stable voltage when the power supply is input in a wide voltage range; the second voltage division circuit and the power supply output control switch circuit are connected in parallel and are arranged between the power supply input end and the power supply output end of the direct-current power supply, and the first voltage division circuit can divide the stable voltage generated by the voltage stabilizing circuit; the first voltage division circuit is connected with the in-phase end of the comparator to provide reference voltage for the comparator, the second voltage division circuit is connected with the anti-phase end of the comparator to provide input voltage for the comparator, and the comparator can compare the reference voltage with an input voltage signal. When the input voltage is higher than the reference voltage, the output end of the comparator outputs a signal for controlling the switching circuit to close to the power supply. The overvoltage protection circuit is sufficient and accurate in overvoltage protection, can be applied to a relatively wide voltage range, and is low in cost.

Description

Technical Field

[0001] This utility model relates to the field of oxygen generator technology, and in particular to a DC power input protection circuit. Background Technology

[0002] Currently, the existing protection measures for DC power supplies on the market all use varistors and fuses. When the input voltage of the product is too high, the varistor breaks down and triggers the protection, which will cause the upstream power supply to trip or be protected. In addition, the varistor may explode and cause the fuse to blow, damaging the product. Moreover, this type of protection has relatively low accuracy and a narrow protection voltage range. Utility Model Content

[0003] To overcome the above-mentioned defects, this utility model provides a DC power input protection circuit, which achieves full protection of the protected equipment or circuit module with high protection accuracy.

[0004] The technical solution adopted by this utility model to solve its technical problem is as follows: A DC power input protection circuit includes a transient absorption circuit, a voltage regulator circuit, a first voltage divider circuit, a second voltage divider circuit, an overvoltage protection circuit, and a power output control switch circuit. The transient absorption circuit, the voltage regulator circuit, the second voltage divider circuit, and the power output control switch circuit are connected in parallel between the power input terminal and the power output terminal of the DC power supply. The transient absorption circuit can absorb and protect against instantaneous voltage spikes generated by the power input voltage. The voltage regulator circuit can generate a stable voltage for the power supply under a wide voltage input range. The second voltage divider circuit can divide the power input voltage. The first voltage divider circuit is connected to the voltage regulator circuit. The overvoltage protection circuit is capable of dividing the stable voltage generated by the voltage regulator circuit. It includes a comparator, with a first voltage divider circuit connected to the non-inverting input of the comparator, providing a reference voltage. A second voltage divider circuit is connected to the inverting input of the comparator, providing an input voltage. The comparator in the second voltage divider circuit can compare the reference voltage and the input voltage signal. The output of the comparator in the overvoltage protection circuit is connected to a power output control switch circuit. When the input voltage is higher than the reference voltage, the comparator output of the overvoltage protection circuit sends a shutdown signal to the power output control switch circuit, which then stops outputting voltage.

[0005] As a further improvement of this utility model, a reverse protection diode is connected in series between the power input terminal of the DC power supply and the transient absorption circuit. The reverse protection diode is used to realize reverse current protection between the power input terminal and the power output terminal.

[0006] As a further improvement of this utility model, the transient absorption circuit includes a TVS diode (transient voltage suppressor) connected in parallel in the circuit.

[0007] As a further improvement of this utility model, the voltage regulator circuit includes a first capacitor, a first resistor, and a Zener diode. The positive terminal of the DC power supply circuit is connected to the positive terminals of the first resistor and the first capacitor, the negative terminal of the first resistor is connected to the negative terminal of the Zener diode, and the positive terminal of the Zener diode and the negative terminal of the first capacitor are connected to the negative terminal of the DC power supply circuit.

[0008] As a further improvement of this utility model, the first voltage divider circuit includes a second resistor and a third resistor connected in series, wherein the second resistor is connected to the common connection point of the first resistor and the Zener diode, the third resistor is connected to the negative terminal of the DC power supply circuit, and the common connection point of the second resistor and the third resistor is connected to the non-inverting input of the comparator; the second voltage divider circuit includes a fourth resistor and a fifth resistor connected in series, wherein the fourth resistor is connected to the positive terminal of the DC power supply circuit, the fifth resistor is connected to the negative terminal of the DC power supply circuit, and the common connection point of the fourth resistor and the fifth resistor is connected to the inverting input of the comparator; the high level output of the comparator is the stable voltage output by the voltage regulator circuit, and the low level output of the comparator is the ground voltage.

[0009] As a further improvement of this utility model, the overvoltage protection circuit also includes a sixth resistor and a second capacitor. The output terminal of the comparator is connected to the sixth resistor, the sixth resistor and the second capacitor are connected in series, the second capacitor is connected to the negative terminal of the DC power supply circuit, and the common connection point of the sixth resistor and the second capacitor is connected to the power output control switch circuit. If the input voltage signal is higher than the reference voltage, the comparator sends a shutdown signal to the power output control switch circuit through the sixth resistor and the second capacitor, so that there is no voltage output at the power output terminal.

[0010] As a further improvement of this utility model, the power output control switch circuit includes a transistor, a seventh resistor, an eighth resistor, and a MOSFET. The common connection point of the sixth resistor and the second capacitor is connected to the base of the transistor in the overvoltage protection circuit. The emitter of the transistor is connected to the negative terminal of the DC power supply circuit. The collector of the transistor is connected to the seventh resistor. The seventh resistor and the eighth resistor are connected in series. The eighth resistor is connected to the positive terminal of the DC power supply circuit. The positive terminal of the DC power supply circuit is connected to the source (S) terminal of the MOSFET. The drain (D) terminal of the MOSFET is connected to the power output terminal. The gate (G) terminal of the MOSFET is connected to the common connection point of the seventh and eighth resistors.

[0011] As a further improvement of this utility model, the power output control switch circuit further includes a third capacitor, which is connected in parallel with the eighth resistor to form a filter circuit.

[0012] As a further improvement of this utility model, the transistor is an NPN type transistor.

[0013] As a further improvement of this utility model, the MOS transistor is a P-channel transistor, and a unidirectional diode from the drain (D) to the source (S) is disposed on the MOS transistor.

[0014] The beneficial effects of this utility model are: This utility model achieves triple protection against reverse polarity connection of the power supply, instantaneous voltage spikes, and input power overvoltage; moreover, the overvoltage protection accuracy can reach 0.2V, which is an order of magnitude higher than the protection accuracy of about 15V of the varistor, and nearly 7 times higher. This utility model has obvious advantages over simple overvoltage protection, simple reverse connection protection, and simple spike absorption circuit: it uses fewer electronic components, has complete protection functions, more accurate overvoltage protection voltage value, and can be applied to a wider voltage range. Attached Figure Description

[0015] Figure 1 This is a block diagram showing the location of the present invention in various application scenarios;

[0016] Figure 2 This is the circuit diagram of this utility model;

[0017] Figure 3 This is a schematic diagram of the module division of this utility model. Detailed Implementation

[0018] Example: A DC power supply input protection circuit includes a transient absorption circuit, a voltage regulator circuit, a first voltage divider circuit, a second voltage divider circuit, an overvoltage protection circuit, and a power output control switch circuit. The transient absorption circuit, voltage regulator circuit, second voltage divider circuit, and power output control switch circuit are connected in parallel between the power input terminal and the power output terminal of the DC power supply. The transient absorption circuit can absorb and protect against transient voltage spikes generated by the power input voltage. The voltage regulator circuit can generate a stable voltage under a wide voltage input range. The second voltage divider circuit can divide the power input voltage. The first voltage divider circuit is connected to the voltage regulator circuit and can divide the stable voltage generated by the voltage regulator circuit. The overvoltage protection circuit includes a comparator U1A. A first voltage divider circuit is connected to the non-inverting input of the comparator U1A in the overvoltage protection circuit, providing a reference voltage to the comparator U1A. A second voltage divider circuit is connected to the inverting input of the comparator U1A in the overvoltage protection circuit, providing an input voltage to the comparator U1A. The comparator U1A in the second voltage divider circuit can compare the reference voltage and the input voltage signal. The output terminal of the comparator U1A in the overvoltage protection circuit is connected to the power output control switch circuit. When the input voltage is higher than the reference voltage, the output terminal of the comparator U1A in the overvoltage protection circuit sends a shutdown signal to the power output control switch circuit, and the power output control switch circuit stops outputting voltage.

[0019] After the DC power supply is input, the transient absorption circuit absorbs and protects against instantaneous voltage spikes. A stable voltage is generated by the voltage regulator circuit. The first and second voltage divider circuits divide the stable voltage and the input voltage respectively, and then input them to the comparator U1A of the overvoltage protection circuit. The comparator U1A compares the two voltages to control the power output and control the switching circuit, thereby preventing excessive voltage from being output to the protected equipment or circuit module. This provides sufficient protection for the protected equipment or circuit module. This protection circuit avoids the use of varistors, and even if the input voltage is too high, it will not damage the downstream equipment and components in the protection circuit, thus improving the stability of electronic products.

[0020] A reverse protection diode D3 is connected in series between the power input terminal of the DC power supply and the transient absorption circuit. The reverse protection diode D3 is used to provide reverse current protection between the power input terminal and the power output terminal. The reverse protection diode can prevent the positive and negative terminals of the power supply from being reversed, thus protecting the protected equipment or circuit module.

[0021] The transient absorption circuit includes a TVS diode D1 (transient voltage suppressor) connected in parallel in the circuit. The TVS diode D1 can absorb transient voltage spikes generated by the power supply input voltage.

[0022] The voltage regulator circuit includes a first capacitor C2, a first resistor R1, and a Zener diode D2. The positive terminal of the DC power supply circuit is connected to the positive terminals of the first resistor R1 and the first capacitor C2, and the negative terminal of the first resistor R1 is connected to the negative terminal of the Zener diode D2. The positive terminal of the Zener diode and the negative terminal of the first capacitor C2 are connected to the negative terminal of the DC power supply circuit. The first resistor R1 and the Zener diode D2 are connected in series and then in parallel with the first capacitor C2 to form a voltage regulator and simultaneously create a reference voltage.

[0023] The first voltage divider circuit includes a second resistor R4 and a third resistor R7 connected in series. The second resistor R4 is connected to the common connection point of the first resistor R1 and the Zener diode D2. The third resistor R7 is connected to the negative terminal of the DC power supply circuit. The common connection point of the second resistor R4 and the third resistor R7 is connected to the non-inverting input of comparator U1A. The second voltage divider circuit includes a fourth resistor R2 and a fifth resistor R8 connected in series. The fourth resistor R2 is connected to the positive terminal of the DC power supply circuit, and the fifth resistor R8 is connected to the negative terminal of the DC power supply circuit. The common connection point of the fourth resistor R2 and the fifth resistor R8 is connected to the inverting input of comparator U1A. The high-level output of comparator U1A is the stable voltage output by the voltage regulator circuit, and the low-level output of comparator U1A is the ground voltage. Voltage division is achieved through the two resistors connected in series. The voltage division can be adjusted according to the ratio of the two resistors before being output to comparator U1A to prevent damage to comparator U1A due to excessive voltage.

[0024] The overvoltage protection circuit also includes a sixth resistor R5 and a second capacitor C3. The output terminal of the comparator U1A is connected to the sixth resistor R5. The sixth resistor R5 and the second capacitor C3 are connected in series. The second capacitor C3 is connected to the negative terminal of the DC power supply circuit. The common connection point of the sixth resistor R5 and the second capacitor C3 is connected to the power output control switch circuit. If the input voltage signal is higher than the reference voltage (the withstand voltage of the device or circuit module to be protected), the comparator U1A sends a shut-off signal to the power output control switch circuit through the sixth resistor R5 and the second capacitor C3, so that there is no voltage output at the power output terminal, and the power supply voltage is stopped from being output to the protected device or circuit module.

[0025] The power output control switch circuit includes a transistor Q1, a seventh resistor R6, an eighth resistor R3, and a MOSFET T1. The common connection point of the sixth resistor R5 and the second capacitor C3 is connected to the base of the transistor Q1 in the overvoltage protection circuit. The emitter of transistor Q1 is connected to the negative terminal of the DC power supply circuit. The collector of transistor Q1 is connected to the seventh resistor R6. The seventh resistor R6 and the eighth resistor R3 are connected in series. The eighth resistor R3 is connected to the positive terminal of the DC power supply circuit. The positive terminal of the DC power supply circuit is connected to the source (S) terminal of MOSFET T1. The drain (D) terminal of MOSFET T1 is connected to the power output terminal. The gate (G) terminal of MOSFET T1 is connected to the common connection point of the seventh resistor R6 and the eighth resistor R3. When the comparator U1A outputs a low level, it controls transistor Q1 to turn off, thereby shutting down MOSFET T1 and ultimately protecting the device or circuit module. When the comparator U1A outputs a high level, it controls transistor Q1 to turn on, thereby turning on MOSFET T1 to supply power to the device or circuit module.

[0026] The power output control switch circuit also includes a third capacitor C1, which is connected in parallel with the eighth resistor R3 to form a filter circuit.

[0027] The transistor Q1 is an NPN transistor.

[0028] The MOSFET T1 is a P-channel transistor, and a unidirectional diode from the drain (D) to the source (S) is disposed on the MOSFET T1.

[0029] The working principle of this DC power input protection circuit is explained below:

[0030] After the DC power supply comes in, reverse connection protection is achieved in the circuit of area A through the reverse protection diode D3D3. If the input voltage spikes, the TVS diode D1D1 can be used to absorb and protect against instantaneous voltage spike pulses.

[0031] The circuit in region B, consisting of the first resistor R1, the Zener diode D2, and the first capacitor C2, functions to generate a stable voltage power supply under a wide voltage range input conditions. The generated stable voltage power supply powers the subsequent comparator U1AU1A in region E and is also used to generate a comparison voltage reference.

[0032] The circuit in region C divides the stable voltage generated by the circuit in region B by the second resistor R4R4 and the third resistor R7R7, providing a comparison reference voltage for the comparator U1AU1A in region E.

[0033] The circuit in region D divides the power input voltage using the fourth resistor R2R2 and the fifth resistor R8R8, providing another set of comparison voltages to the subsequent comparator U1AU1A in region E.

[0034] Area E is an overvoltage protection circuit. Comparator U1AU1A compares the reference voltage generated by the second resistor R4R4 and the third resistor R7R7 with the input voltage signal generated by the fourth resistor R2R2 and the fifth resistor R8R8. If the input voltage signal is higher than the withstand voltage of the device or circuit module to be protected, a shut-off signal is given to the power output control switch circuit in area F through the sixth resistor R5R5 and the second capacitor C3C3, stopping the power supply voltage from being output to the protected device or circuit module.

[0035] Area F is the power output control switch circuit, consisting of MOSFET T1, resistor R3, capacitor C1, resistor R6, and transistor Q1. When comparator U1A outputs a low level, it controls transistor Q1 to turn off, thus shutting down MOSFET T1 and ultimately protecting the device or circuit module; when comparator U1A outputs a high level, it controls transistor Q1 to turn on, thus turning on MOSFET T1 and supplying power to the subsequent device or circuit module.

Claims

1. A DC power input protection circuit, characterized in that: The power supply includes a transient absorption circuit, a voltage regulator circuit, a first voltage divider circuit, a second voltage divider circuit, an overvoltage protection circuit, and a power output control switch circuit. The transient absorption circuit, voltage regulator circuit, second voltage divider circuit, and power output control switch circuit are connected in parallel between the power input and output terminals of the DC power supply. The transient absorption circuit absorbs and protects against transient voltage spikes generated by the power input voltage. The voltage regulator circuit generates a stable voltage under a wide voltage input range. The second voltage divider circuit divides the power input voltage. The first voltage divider circuit is connected to the voltage regulator circuit and divides the stable voltage generated by the voltage regulator circuit. The overvoltage protection circuit includes a comparator (U1A). The first voltage divider circuit is connected to the non-inverting input of the comparator in the overvoltage protection circuit, providing a reference voltage to the comparator. The second voltage divider circuit is connected to the inverting input of the comparator in the overvoltage protection circuit, providing an input voltage. The comparator in the second voltage divider circuit can compare the reference voltage and the input voltage signal. The output of the comparator in the overvoltage protection circuit is connected to the power output control switch circuit. When the input voltage is higher than the reference voltage, the output of the comparator in the overvoltage protection circuit sends a shutdown signal to the power output control switch circuit, which then stops outputting voltage.

2. The DC power input protection circuit according to claim 1, characterized in that: A reverse protection diode (D3) is connected in series between the power input terminal of the DC power supply and the transient absorption circuit. The reverse protection diode is used to realize reverse current protection between the power input terminal and the power output terminal.

3. The DC power input protection circuit according to claim 1, characterized in that: The transient absorption circuit includes a TVS diode (transient voltage suppressor) (D1) connected in parallel in the circuit.

4. The DC power input protection circuit according to claim 1, characterized in that: The voltage regulator circuit includes a first capacitor (C2), a first resistor (R1), and a Zener diode (D2). The positive terminal of the DC power supply circuit is connected to the positive terminals of the first resistor and the first capacitor, the negative terminal of the first resistor is connected to the negative terminal of the Zener diode, and the positive terminal of the Zener diode and the negative terminal of the first capacitor are connected to the negative terminal of the DC power supply circuit.

5. The DC power input protection circuit according to claim 4, characterized in that: The first voltage divider circuit includes a second resistor (R4) and a third resistor (R7) connected in series. The second resistor is connected to the common connection point of the first resistor and the Zener diode, and the third resistor is connected to the negative terminal of the DC power supply circuit. The common connection point of the second and third resistors is connected to the non-inverting input of the comparator. The second voltage divider circuit includes a fourth resistor (R2) and a fifth resistor (R8) connected in series. The fourth resistor is connected to the positive terminal of the DC power supply circuit, and the fifth resistor is connected to the negative terminal of the DC power supply circuit. The common connection point of the fourth and fifth resistors is connected to the inverting input of the comparator. The high output level of the comparator is the stable voltage output by the voltage regulator circuit, and the low output level of the comparator is the ground voltage.

6. The DC power input protection circuit according to claim 1, characterized in that: The overvoltage protection circuit also includes a sixth resistor (R5) and a second capacitor (C3). The output terminal of the comparator is connected to the sixth resistor, the sixth resistor and the second capacitor are connected in series, the second capacitor is connected to the negative terminal of the DC power supply circuit, and the common connection point of the sixth resistor and the second capacitor is connected to the power output control switch circuit. If the input voltage signal is higher than the reference voltage, the comparator sends a shutdown signal to the power output control switch circuit through the sixth resistor and the second capacitor, so that there is no voltage output at the power output terminal.

7. The DC power input protection circuit according to claim 6, characterized in that: The power output control switch circuit includes a transistor (Q1), a seventh resistor (R6), an eighth resistor (R3), and a MOSFET (T1). The common connection point of the sixth resistor and the second capacitor is connected to the base of the transistor in the overvoltage protection circuit. The emitter of the transistor is connected to the negative terminal of the DC power supply circuit. The collector of the transistor is connected to the seventh resistor. The seventh and eighth resistors are connected in series. The eighth resistor is connected to the positive terminal of the DC power supply circuit. The positive terminal of the DC power supply circuit is connected to the source (S) terminal of the MOSFET. The drain (D) terminal of the MOSFET is connected to the power output terminal. The gate (G) terminal of the MOSFET is connected to the common connection point of the seventh and eighth resistors.

8. The DC power input protection circuit according to claim 7, characterized in that: The power output control switch circuit also includes a third capacitor (C1), which is connected in parallel with the eighth resistor to form a filter circuit.

9. The DC power input protection circuit according to claim 7, characterized in that: The transistor is an NPN type transistor.

10. The DC power input protection circuit according to claim 7, characterized in that: The MOS transistor is a P-channel transistor, and a unidirectional diode is disposed on the MOS transistor from the drain (D) to the source (S).

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