Disclosure of utility model
The embodiment of the utility model provides a power supply protection circuit and an electronic product, which are used for solving the problem of poor voltage protection control effect.
The embodiment of the utility model provides a power supply protection circuit, which comprises a voltage protection circuit and an anti-reverse connection circuit;
The input end of the anti-reverse connection circuit is used for being connected with a power supply, the output end of the anti-reverse connection circuit is connected with the voltage protection circuit and is used for being cut off when the power supply protection circuit is reversely connected with the power supply, and the anti-reverse connection circuit is conducted when the power supply protection circuit is positively connected with the power supply;
The output end of the voltage protection circuit is used for being connected with a power supply circuit and used for being cut off when the power supply voltage of the power supply is not in the range of the reference voltage.
Preferably, the reverse connection preventing circuit comprises a first control tube, a first resistor, a second resistor and a first diode;
The first end of the first control tube is connected with the negative electrode end of the power supply, and the second end of the first control tube is connected with the positive electrode end of the power supply through the first resistor, and the third end of the first control tube is grounded;
The anode of the first diode is connected with the third end of the first control tube, and the cathode of the first diode is connected with a connection node between the first resistor and the first control tube;
The first end of the second resistor is connected with the cathode of the first diode, and the second end of the second resistor R2 is grounded.
Preferably, the voltage protection circuit includes a voltage detection circuit and a protection action circuit;
The input end of the voltage detection circuit is connected with the power supply and the reference voltage source, and the output end of the voltage detection circuit is connected with the protection action circuit and is used for outputting a protection action signal to the protection action circuit when the power supply voltage of the power supply is larger than the first reference voltage or smaller than the second reference voltage;
The protection action circuit is connected with the power supply circuit and is used for stopping supplying power to the power supply circuit when receiving the protection action signal.
Preferably, the voltage detection circuit comprises an undervoltage detection circuit, an overvoltage detection circuit and a control chip;
The input end of the overvoltage detection circuit is connected with the power supply and the reference voltage source, and the output end of the overvoltage detection circuit is connected with the second input end of the control chip and is used for outputting an overvoltage signal to the protection action circuit when the power supply voltage of the power supply is greater than the first reference voltage;
The input end of the undervoltage detection circuit is connected with the power supply and the reference voltage source, and the output end of the undervoltage detection circuit is connected with the first input end of the control chip and is used for outputting an undervoltage signal to the protection action circuit when the power supply voltage of the power supply is smaller than the second reference voltage;
The output end of the control chip is connected with the protection action circuit and is used for outputting a protection action signal to the protection action circuit when the overvoltage signal or the undervoltage signal is received.
Preferably, the undervoltage detection circuit comprises a first comparator, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor and a seventh resistor;
the inverting input end of the first comparator is connected with the reference voltage source through the third resistor, the non-inverting input end of the first comparator is connected with the power supply through the fourth resistor, and the output end of the first comparator is connected with the first input end of the control chip through the fifth resistor;
The first end of the sixth resistor is connected with the inverting input end of the first comparator, and the second end of the sixth resistor is grounded;
The first end of the seventh resistor is connected with the non-inverting input end of the first comparator, and the second end of the seventh resistor is grounded.
Preferably, the undervoltage detection circuit further comprises a first return difference monitoring control circuit, wherein the first return difference monitoring control circuit comprises a second control tube, an eighth resistor and a second diode;
The first end of the second control tube is connected with the second end of the sixth resistor, the second end of the second control tube is connected with the cathode of the second diode, the anode of the second diode is connected with the connection node between the fifth resistor and the control chip, and the third end of the second control tube is grounded;
and two ends of the eighth resistor are respectively connected with the first end and the third end of the second control tube.
Preferably, the overvoltage detection circuit includes a second comparator, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, and a thirteenth resistor;
The non-inverting input end of the second comparator is connected with the reference voltage source through the ninth resistor, the inverting input end of the second comparator is connected with the power supply through the tenth resistor, and the output end of the second comparator is connected with the second input end of the control chip through the eleventh resistor;
A first end of the twelfth resistor is connected with the inverting input end of the second comparator, and a second end of the twelfth resistor is grounded;
the first end of the thirteenth resistor is connected with the non-inverting input end of the second comparator, and the second end of the thirteenth resistor is grounded.
Preferably, the overvoltage detection circuit further comprises a second return difference monitoring control circuit, wherein the second return difference monitoring control circuit comprises a third control tube, a fourteenth resistor and a third diode;
The first end of the third control tube is connected with the second end of the twelfth resistor, the second end of the third control tube is connected with the cathode of the third diode, the anode of the third diode is connected with the connection node between the eleventh resistor and the control chip, and the third end of the third control tube is grounded;
And two ends of the fourteenth resistor are respectively connected with the first end and the third end of the third control tube.
Preferably, the protection action circuit includes a fourth control tube, a fifth control tube, a fifteenth resistor, a sixteenth resistor, and a seventeenth resistor;
The first end of the fourth control tube is connected with the output end of the voltage detection circuit through the fifteenth resistor, and the second end of the fourth control tube is connected with the first end of the fifth control tube through the sixteenth resistor; the third end of the fourth control tube is grounded;
The second end of the fifth control tube is connected with the power supply, and the third end of the fifth control tube is used for being connected with a power supply circuit;
And two ends of the seventeenth resistor are respectively connected with the first end and the second end of the fifth control tube.
Preferably, the protection circuit further comprises an input filter module and an output filter module;
The first end of the input filter module is used for being connected with a power supply, and the second end of the input filter module is connected with the reverse connection preventing circuit;
the first end of the output filter module is connected with the voltage protection circuit, and the second end of the output filter module is used for being connected with the power supply circuit.
The embodiment of the utility model also provides an electronic product, which comprises a power supply circuit and any one of the power supply protection circuits;
The input end of the power supply protection circuit is used for being connected with a power supply, and the output end of the protection circuit is connected with the power supply circuit.
According to the power supply protection circuit and the electronic product, the voltage protection circuit and the reverse connection prevention circuit are additionally arranged at the input end of the power supply circuit of the electronic product, so that when the power supply is reversely connected, the power supply voltage input can be cut off, and the later stage reverse connection prevention circuit and the power supply circuit are protected; and when the power supply voltage is not in the reference voltage range, the power supply voltage input can be cut off in time, so that the power supply circuit of the later stage is further protected, and the safe operation of the power supply circuit is ensured.
Detailed Description
The following description of the embodiments of the present utility model will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.
It should be understood that the present utility model may be embodied in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the utility model to those skilled in the art. In the drawings, the dimensions and relative dimensions of layers and regions may be exaggerated for the same elements throughout for clarity.
It will be understood that when an element or layer is referred to as being "on" …, "" adjacent to "…," "connected to" or "coupled to" another element or layer, it can be directly on, adjacent to, connected to or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on" …, "" directly adjacent to "…," "directly connected to" or "directly coupled to" another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present utility model.
Spatially relative terms, such as "under …," "under …," "below," "under …," "over …," "above," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use and operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements or features described as "under" or "beneath" other elements would then be oriented "on" the other elements or features. Thus, the exemplary terms "below …" and "under …" may include both an upper and a lower orientation. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatially relative descriptors used herein interpreted accordingly.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.
In the following description, for the purpose of providing a thorough understanding of the present utility model, detailed structures and steps are presented in order to illustrate the technical solution presented by the present utility model. Preferred embodiments of the present utility model are described in detail below, however, the present utility model may have other embodiments in addition to these detailed descriptions.
The embodiment of the utility model provides a power supply protection circuit, which comprises a voltage protection circuit 1 and an anti-reverse connection circuit 2; the input end of the anti-reverse connection circuit 2 is used for being connected with a power supply 3, the output end of the anti-reverse connection circuit 2 is connected with the voltage protection circuit 1 and is used for being cut off when the power supply protection circuit is reversely connected with the power supply 3, and is conducted when the power supply protection circuit is positively connected with the power supply 3; the output of the voltage protection circuit 1 is connected to a power supply circuit 4 for switching off when the supply voltage VIN of the supply source 3 is not within a reference voltage range.
The reference voltage range is larger than the second reference voltage and smaller than the first reference voltage.
The power protection circuit can be arranged at the input end of the power circuit 4 of the electronic product, and is used for protecting the rear-stage power circuit 4 aiming at the power supply voltage VIN when the external power supply 3 is connected to the power circuit 4. The power supply 3 may be a power supply device such as a battery, including a positive terminal and a negative terminal.
As an example, the power supply protection circuit comprises a voltage protection circuit 1 and an anti-reverse connection circuit 2, wherein the input end of the anti-reverse connection circuit 2 is connected with a power supply 3, the output end of the anti-reverse connection circuit 2 is connected with the voltage protection circuit 1, and the output end of the voltage protection circuit 1 is used for being connected with a power supply circuit 4. When the power supply 3 is reversely connected into the power supply protection circuit, the reverse connection prevention circuit 2 is cut off, and the power supply voltage VIN cannot be input into the voltage protection circuit 1 and the power supply circuit 4 at the later stage, so that protection is formed for the voltage protection circuit 1 and the power supply circuit 4; when the power supply 3 is connected to the power protection circuit, the anti-reverse connection circuit 2 is turned on, and the power supply voltage VIN can be input to the voltage protection circuit 1 at the subsequent stage. The voltage protection circuit 1 detects the power supply voltage VIN, and when the power supply voltage VIN is greater than the first reference voltage or less than the second reference voltage, the voltage protection circuit 1 is turned off, the power supply circuit 4 has no voltage input, and the power supply circuit 4 is protected from being damaged by abnormal voltages. When the supply voltage VIN is within the reference voltage range, the voltage protection circuit 1 can be smoothly turned on, the supply power 3 supplies power to the power supply circuit 4 in the electronic product, and when the supply voltage VIN is equal to the second reference voltage or the first reference voltage, the voltage protection circuit 1 is in a critical state to keep the on or off state at the previous moment.
In the example, by arranging the voltage protection circuit 1 and the reverse connection preventing circuit 2, when the power supply 3 is reversely connected, the input of the power supply voltage VIN can be cut off, and the protection is formed for the rear reverse connection preventing circuit 2 and the power supply circuit 4; when the power supply voltage VIN is not in the reference voltage range, the input of the power supply voltage VIN can be cut off in time, the power supply circuit 4 of the later stage is further protected, and the safe operation of the power supply circuit 4 is ensured.
In one embodiment, the anti-reverse connection circuit 2 includes a first control tube Q1, a first resistor R1, a second resistor R2, and a first diode D1; the first end of the first control tube Q1 is connected with the negative electrode end of the power supply 3, the second end of the first control tube Q1 is connected with the positive electrode end of the power supply 3 through the first resistor R1, and the third end of the first control tube Q1 is grounded; the anode of the first diode D1 is connected with the third end of the first control tube Q1, and the cathode of the first diode D1 is connected with a connection node between the first resistor R1 and the first control tube Q1; the first end of the second resistor R2 is connected with the cathode of the first diode D1, and the second end of the second resistor R2 is grounded.
As an example, the anti-reverse connection circuit 2 includes a first control tube Q1, a first resistor R1, a second resistor R2, and a first diode D1. The first control tube Q1 may be an NMOS tube, the first end of the first control tube Q1 is the drain electrode of the NMOS tube, the second end of the first control tube Q1 is the gate electrode of the NMOS tube, and the third end of the first control tube Q1 is the source electrode of the NMOS tube. The drain electrode of the first control tube Q1 is used for being connected with the negative electrode of the power supply 3, the grid electrode of the first control tube Q1 is connected with the positive electrode end of the power supply 3 through a first resistor R1, the first end of the second resistor R2 is connected with a connecting node between the first control tube Q1 and the first resistor R1 to form a voltage division effect, and the source electrode of the first control tube Q1 is grounded. The first diode D1 is a zener diode, an anode of the zener diode is connected to a source electrode of the first control tube Q1, and a cathode of the zener diode is connected to a gate electrode of the first control tube Q1, so as to ensure that the gate voltage of the first control tube Q1 does not exceed a preset voltage value.
When the power supply 3 is normally connected to the power supply protection circuit, the power supply voltage VIN is input to the gate of the first control tube Q1 through the voltage division of the first resistor R1 and the second resistor R2, at this time, the voltage Vgs between the gate and the source of the first control tube Q1 is positive, the first control tube Q1 is saturated and turned on, the negative electrode of the power supply 3 is grounded, and the negative electrode of the power supply 3 is approximately short-circuited with ground. When the power supply 3 is reversely connected to the power supply protection circuit, the voltage Vgs between the grid electrode and the source electrode of the first control tube Q1 is negative, the first control tube Q1 is cut off, the negative end of the power supply 3 is approximately open to the ground, the power supply cannot form a backflow path, the reverse connection prevention circuit 2 is cut off, and the power supply 3 cannot provide energy input for the subsequent voltage protection circuit 1 and the power supply circuit 4, so that the reverse connection prevention purpose is achieved. In this example, the first control tube Q1 is used to make a short circuit between the drain and the source when saturated conduction is performed, and the impedance is low; when the power supply is cut off, the impedance is high, the characteristic of approximate open circuit between the drain electrode and the source electrode can reduce the transmission loss of the power supply voltage VIN.
In one embodiment, the voltage protection circuit 1 includes a voltage detection circuit 11 and a protection action circuit 12; the input end of the voltage detection circuit 11 is connected with the power supply 3 and a reference voltage source, and the output end of the voltage detection circuit 11 is connected with the protection action circuit 12 and is used for outputting a protection action signal to the protection action circuit 12 when the power supply voltage VIN of the power supply 3 is larger than a first reference voltage or smaller than a second reference voltage; and the protection action circuit 12 is connected with the power circuit 4 and is used for stopping supplying power to the power circuit 4 when receiving the protection action signal.
As shown in fig. 2, the reference voltage source may be generated by a high-precision linear voltage stabilizing chip U1, where an input end of the voltage stabilizing chip U1 is connected to an anode end of the power supply 3, and an output voltage obtained by processing the power supply voltage VIN output by the power supply 3 may be used as the reference voltage source in the circuit.
As an example, as shown in fig. 3, the voltage protection circuit 1 includes a voltage detection circuit 11 and a protection action circuit 12; the input end of the voltage detection circuit 11 is connected with the power supply 3 and a reference voltage source, the output end of the voltage detection circuit 11 is connected with the input end of the protection action circuit 12, and the output end of the protection action circuit 12 is connected with the power supply circuit 4. When the voltage detection circuit 11 detects that the power supply voltage VIN of the power supply 3 is greater than the first reference voltage or less than the second reference voltage, a protection action signal is output to the protection action circuit 12, and the protection action circuit 12 stops supplying power to the power supply circuit 4 when receiving the protection action signal, so that the effect of abnormal protection of the power supply voltage VIN is achieved.
In one embodiment, the voltage detection circuit 11 includes an undervoltage detection circuit 111, an overvoltage detection circuit 112, and a control chip U2; the input end of the overvoltage detection circuit 112 is connected with the power supply 3 and a reference voltage source, and the output end of the overvoltage detection circuit 112 is connected with the first input end of the control chip U2 and is used for outputting an overvoltage signal to the protection action circuit 12 when the power supply voltage VIN of the power supply 3 is greater than a first reference voltage; the input end of the undervoltage detection circuit 111 is connected with the power supply 3 and a reference voltage source, and the output end of the undervoltage detection circuit 111 is connected with the second input end of the control chip U2, and is used for outputting an undervoltage signal to the protection action circuit 12 when the power supply voltage VIN of the power supply 3 is smaller than a second reference voltage; the output end of the control chip U2 is connected to the protection action circuit 12, and is used for outputting a protection action signal to the protection action circuit 12 when receiving an overvoltage signal or an undervoltage signal.
As an example, the voltage detection circuit 11 includes an overvoltage detection circuit 112, an undervoltage detection circuit 111, and a control chip U2. The input end of the overvoltage detection circuit 112 is connected with the power supply 3 and the reference voltage source, the output end of the overvoltage detection circuit 112 is connected with the first input end of the control chip U2, the input end of the undervoltage detection circuit 111 is connected with the power supply 3 and the reference voltage source, and the output end of the undervoltage detection circuit 111 is connected with the second input end of the control chip U2.
When the supply voltage VIN of the power supply 3 is greater than the first reference voltage, the overvoltage detection circuit 112 outputs an overvoltage signal to the control chip U2, when the supply voltage VIN of the power supply 3 is less than the second reference voltage, the undervoltage detection circuit 111 outputs an undervoltage signal to the control chip U2, the control chip U2 may be an and gate chip, when at least one of the two inputs is at a low level, the output is at a low level, when both inputs are at a high level, the output is at a high level, when the undervoltage detection circuit 111 outputs an undervoltage signal or the overvoltage detection circuit 112 outputs an overvoltage signal, the protection action signal is output to the protection action circuit 12, and when the undervoltage detection circuit 111 does not output an undervoltage signal and the overvoltage detection circuit 112 does not output an overvoltage signal, the protection action signal is also not output at the protection action circuit 12. By arranging the undervoltage detection circuit 111, the overvoltage detection circuit 112 and the control chip U2, the control voltage abnormality protection range can be accurately controlled, and the voltage abnormality can be accurately judged.
In an embodiment, the undervoltage detection circuit 111 includes a first comparator U1A, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7; the inverting input end of the first comparator U1A is connected with a reference voltage source through a third resistor R3, the non-inverting input end of the first comparator U1A is connected with a power supply 3 through a fourth resistor R4, and the output end of the first comparator U1A is connected with the first input end of the control chip U2 through a fifth resistor R5; the first end of the sixth resistor R6 is connected with the inverting input end of the first comparator U1A, and the second end of the sixth resistor R6 is grounded; the first end of the seventh resistor R7 is connected to the non-inverting input of the first comparator U1A, and the second end of the seventh resistor R7 is grounded.
As an example, the undervoltage detection circuit 111 includes a first comparator U1A, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7. The inverting input end of the first comparator U1A is connected with a reference voltage source through a third resistor R3, the non-inverting input end of the first comparator U1A is connected with a power supply 3 through a fourth resistor R4, and the output end of the first comparator U1A is connected with the first input end of the control chip U2 through a fifth resistor R5. The third resistor R3, the fourth resistor R4 and the fifth resistor R5 play a role in current limiting. The first end of the sixth resistor R6 is connected to the inverting input end of the first comparator U1A, the second end of the sixth resistor R6 is grounded, the sixth resistor R6 and the third resistor R3 form a voltage division to the reference voltage VCC output by the reference voltage source, and by adjusting the resistance values of the third resistor R3 and the sixth resistor R6, the magnitude of the voltage UN input to the inverting input end of the first comparator U1A by the reference voltage VCC can be adjusted, u1n=vcc (R6/(r3+r6)); the first end of the seventh resistor R7 is connected to the non-inverting input terminal of the first comparator U1A, the second end of the seventh resistor R7 is grounded, the seventh resistor R7 and the fourth resistor R4 form a voltage division function on the power supply voltage VIN, and by adjusting the resistances of the fourth resistor R4 and the seventh resistor R7, the magnitude of the voltage UP input to the non-inverting input terminal of the first comparator U1A of the power supply voltage VIN can be adjusted, and u1p=vin (r7/(r4+r7)). When the voltage of the non-inverting input end of the first comparator U1A is greater than the voltage of the inverting input end, the power supply voltage VIN is greater than the second reference voltage, the power supply voltage VIN is in a normal state, the first comparator U1A outputs a high level to the and gate chip, if the overvoltage detection circuit 112 also outputs a high level, the and gate chip outputs a high level, and the voltage protection circuit 1 is normally turned on; when the voltage of the inverting input end of the first comparator U1A is greater than the voltage of the non-inverting input end, the supply voltage VIN is indicated to be smaller than the second reference voltage, and at this time, the supply voltage VIN is in an undervoltage state, the first comparator U1A outputs a low level, that is, an undervoltage signal to the and gate chip, and the and gate chip outputs a low level signal, that is, outputs a protection action signal. When the non-inverting input terminal voltage of the first comparator U1A is equal to the inverting input terminal voltage, the first comparator U1A holds the output at the previous time.
In an embodiment, the undervoltage detection circuit 111 further includes a first return difference monitoring control circuit 1111, where the first return difference monitoring control circuit 1111 includes a second control tube Q2, an eighth resistor R8, and a second diode D2; the first end of the second control tube Q2 is connected with the second end of the sixth resistor R6, the second end of the second control tube Q2 is connected with the cathode of the second diode D2, the anode of the second diode D2 is connected with a connection node between the fifth resistor R5 and the control chip U2, and the third end of the second control tube Q2 is grounded; two ends of the eighth resistor R8 are respectively connected with the first end and the third end of the second control tube Q2.
As an example, the undervoltage detection circuit 111 further includes a first return difference monitoring control circuit 1111. The first return difference monitoring control circuit 1111 includes a second control tube Q2, an eighth resistor R8, and a second diode D2. The second control tube Q2 may be an NMOS tube, the first end of the second control tube Q2 is the drain electrode of the NMOS tube, the second end of the second control tube Q2 is the gate electrode of the NMOS tube, and the third end of the second control tube Q2 is the source electrode of the NMOS tube. The drain electrode of the second control tube Q2 is connected with the second end of the sixth resistor R6, the grid electrode of the second control tube Q2 is connected with the cathode of the second diode D2, the anode of the second diode D2 is connected with the connection node between the fifth resistor R5 and the control chip U2, and the source electrode of the second control tube Q2 is grounded; both ends of the eighth resistor R8 are connected to the drain and source of the second control tube Q2, respectively.
When the supply voltage VIN is smaller than the second reference voltage, the first comparator U1A is switched from high level to low level, the second control tube Q2 is switched from on state to off state, the sixth resistor R6 is connected to the eighth resistor R8 in series, the voltage U1 n=vcc at the inverting input terminal of the first comparator U1A ((r6+r8)/(r3+r6+r8)), the voltage at the inverting input terminal of the first comparator U1A increases, that is, the second reference voltage temporarily increases, so that it is possible to prevent the undervoltage condition from disappearing due to the cut-off of the load supply when the circuit cuts off the output of the supply voltage VIN, the supply voltage VIN rises, and the circuit is turned on again to form frequent switching.
In one embodiment, the overvoltage detection circuit 112 includes a second comparator U2A, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, and a thirteenth resistor R13; the non-inverting input end of the second comparator U2A is connected with a reference voltage source through a ninth resistor R9, the inverting input end of the second comparator U2A is connected with the power supply 3 through a tenth resistor R10, and the output end of the second comparator U2A is connected with the second input end of the control chip U2 through an eleventh resistor R11; the first end of the twelfth resistor R12 is connected with the inverting input end of the second comparator U2A, and the second end of the twelfth resistor R12 is grounded; the first end of the thirteenth resistor R13 is connected to the non-inverting input terminal of the second comparator U2A, and the second end of the thirteenth resistor R13 is grounded.
As an example, the overvoltage detection circuit 112 includes a second comparator U2A, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, and a thirteenth resistor R13. The non-inverting input end of the second comparator U2A is connected with a reference voltage source through a ninth resistor R9, the inverting input end of the second comparator U2A is connected with the power supply 3 through a tenth resistor R10, and the output end of the second comparator U2A is connected with the second input end of the control chip U2 through an eleventh resistor R11, wherein the ninth resistor R9, the tenth resistor R10 and the eleventh resistor R11 play a role in current limiting. The first end of the twelfth resistor R12 is connected with the inverting input end of the second comparator U2A, the second end of the twelfth resistor R12 is grounded, the twelfth resistor R12 and the tenth resistor R10 form a voltage division effect on the power supply voltage VIN, and the magnitude of the voltage U2N input to the inverting input end of the second comparator U2A of the power supply voltage VIN can be adjusted by adjusting the resistance values of the tenth resistor R10 and the twelfth resistor R12, wherein u2n=vin (R12/(r10+r12)); the first end of the thirteenth resistor R13 is connected to the non-inverting input end of the second comparator U2A, the second end of the thirteenth resistor R13 is grounded, the thirteenth resistor R13 and the ninth resistor R9 form a voltage division effect on the reference voltage VCC output by the reference voltage source, and by adjusting the resistance values of the thirteenth resistor R13 and the ninth resistor R9, the voltage U2P of the reference voltage VCC input to the non-inverting input end of the second comparator U2A can be adjusted, and u2p=vcc (R9/(r9+r13)). When the voltage of the non-inverting input end of the second comparator U2A is greater than the voltage of the inverting input end, the power supply voltage VIN is smaller than the first reference voltage, and is in a normal state, the second comparator U2A outputs a high level to the and gate chip, if the undervoltage detection circuit 111 also outputs a high level, the and gate chip outputs a high level, and the voltage protection circuit 1 is normally turned on; when the voltage of the non-inverting input terminal of the second comparator U2A is smaller than the voltage of the inverting input terminal, the supply voltage VIN is larger than the first reference voltage, the supply voltage VIN is in an abnormal overvoltage state, the second comparator U2A outputs a low level, that is, an overvoltage signal to the and gate chip, and the and gate chip outputs a low level signal, that is, outputs a protection action signal. When the non-inverting input terminal voltage of the second comparator U2A is equal to the inverting input terminal voltage, the second comparator U2A maintains the output at the previous time.
In an embodiment, the overvoltage detection circuit 112 further includes a second return difference monitoring control circuit 1121, where the second return difference monitoring control circuit 1121 includes a third control tube Q3, a fourteenth resistor R14, and a third diode D3; the first end of the third control tube Q3 is connected with the second end of the twelfth resistor R12, the second end of the third control tube Q3 is connected with the cathode of the third diode D3, the anode of the third diode D3 is connected with a connecting node between the eleventh resistor R11 and the control chip U2, and the third end of the third control tube Q3 is grounded; both ends of the fourteenth resistor R14 are connected to the first end and the third end of the third control tube Q3, respectively.
As an example, the overvoltage detection circuit 112 further includes a second return difference monitoring control circuit 1121. The second return difference monitoring control circuit 1121 includes a third control tube Q3, a fourteenth resistor R14, and a third diode D3. The third control tube Q3 may be an NMOS tube, the first end of the third control tube Q3 is the drain electrode of the NMOS tube, the second end of the second control tube Q2 is the gate electrode of the NMOS tube, and the third end of the second control tube Q2 is the source electrode of the NMOS tube. The drain electrode of the third control tube Q3 is connected with the second end of the twelfth resistor R12, the grid electrode of the third control tube Q3 is connected with the cathode of the third diode D3, the anode of the third diode D3 is connected with the connecting node between the eleventh resistor R11 and the control chip U2, and the source electrode of the third control tube Q3 is grounded; both ends of the fourteenth resistor R14 are connected to the drain and source of the third control tube Q3, respectively.
When the power supply voltage VIN is greater than the first reference voltage, the output of the second comparator U2A is changed from high level to low level, the third control tube Q3 is changed from on state to off state, the tenth resistor R10 and the twelfth resistor R12 are connected in series, the voltage U2 n=vin of the inverting input terminal of the second comparator U2A ((r12+r14)/(r10+r12+r14)), and the voltage of the inverting input terminal of the second comparator U2A increases, so that it is possible to prevent the over-voltage condition from disappearing due to the cut-off of the power supply of the load when the circuit cuts off the output of the power supply voltage VIN, the power supply voltage VIN decreases, and the circuit is turned on again to form frequent switching.
In one embodiment, the protection action circuit 12 includes a fourth control tube Q4, a fifth control tube Q5, a fifteenth resistor R15, a sixteenth resistor R16, and a seventeenth resistor R17; the first end of the fourth control tube Q4 is connected with the output end of the voltage detection circuit 11 through a fifteenth resistor R15, and the second end of the fourth control tube Q4 is connected with the first end of the fifth control tube Q5 through a sixteenth resistor R16; the third end of the fourth control tube Q4 is grounded; the second end of the fifth control tube Q5 is connected with the power supply 3, and the third end of the fifth control tube Q5 is used for being connected with the power supply circuit 4; both ends of the seventeenth resistor R17 are connected to the first and second ends of the fifth control pipe Q5, respectively.
As an example, the protection action circuit 12 includes a fourth control tube Q4, a fifth control tube Q5, a fifteenth resistor R15, a sixteenth resistor R16, and a seventeenth resistor R17. The fourth control tube Q4 may be an NMOS tube, the first end of the fourth control tube Q4 is a gate of the NMOS tube, the second end of the fourth control tube Q4 is a drain of the NMOS tube, and the third end of the fourth control tube Q4 is a source of the NMOS tube. The grid electrode of the fourth control tube Q4 is connected with the output end of the voltage detection circuit 11 through a fifteenth resistor R15, and the drain electrode of the fourth control tube Q4 is connected with the grid electrode of the fifth control tube Q5 through a sixteenth resistor R16; the source of the fourth control tube Q4 is grounded. The fifth control tube Q5 may be a PMOS tube, the first end of the fifth control tube Q5 is a gate of the PMOS tube, the second end of the fifth control tube Q5 is a source of the PMOS tube, the third end of the fifth control tube Q5 is a drain of the PMOS tube, the drain of the fifth control tube Q5 is connected to the power supply 3, the source of the fifth control tube Q5 is connected to the power supply circuit 4, and two ends of the seventeenth resistor R17 are respectively connected to the gate and the source of the fifth control tube Q5, and are used for providing bias voltage for the fifth control tube Q5.
When the power supply voltage VIN is normal, the AND gate chip outputs a high level, the fourth control tube Q4 is conducted, the grid electrode of the fifth control tube Q5 is pulled down to the ground, the fifth control tube Q5 is conducted, and the power supply voltage VIN is normally output to the power circuit 4; when the supply voltage VIN is abnormal, the and gate chip outputs a low level, the fourth control tube Q4 is turned off, the fifth control tube Q5 is turned off, the protection action circuit 12 is turned off, the supply voltage VIN cannot be output to the power circuit 4, and the effect of abnormal protection of the supply voltage VIN is achieved.
In an embodiment, the power protection circuit further comprises an input filtering module 5 and an output filtering module 6; the first end of the input filter module 5 is used for being connected with the power supply 3, and the second end of the input filter module 5 is connected with the reverse connection preventing circuit 2; the first end of the output filter module 6 is connected with the voltage protection circuit 1, and the second end of the output filter module 6 is used for being connected with the power supply circuit 4.
As an example, the power supply protection circuit further comprises an input filtering module 5 and an output filtering module 6. The first end of the input filter module 5 is used for being connected with the power supply 3, and the second end of the input filter module 5 is connected with the reverse connection preventing circuit 2; the first end of the output filter module 6 is connected with the voltage protection circuit 1, and the second end of the output filter module 6 is used for being connected with the power supply circuit 4. Specifically, the input filter module 5 may include a first filter capacitor and a second filter capacitor connected across the positive terminal and the negative terminal of the power supply 3, and configured to perform a filter process on the power supply voltage VIN input to the power supply protection circuit; the output filter module 6 may include a third filter capacitor and a fourth filter capacitor connected across the output of the protection circuit and ground, for filtering the voltage output by the power protection circuit. As shown in fig. 2, the power protection circuit may further include a fifth filter capacitor and a sixth filter capacitor disposed at the output end of the anti-reverse connection circuit 2, where a first end of the fifth filter capacitor is connected to the positive end of the power supply 3, a second end of the fifth filter capacitor is connected to the source electrode of the first control tube Q1, a first end of the sixth filter capacitor is connected to the positive end of the power supply 3, and a second end of the sixth filter capacitor is connected to the source electrode of the first control tube Q1, and is used for performing filtering processing on the power supply voltage VIN input to the voltage protection circuit 1.
The embodiment of the utility model also provides an electronic product, which comprises a power supply circuit 4 and the power supply protection circuit in the embodiment; the input end of the power supply protection circuit is used for being connected with the power supply 3, and the output end of the protection circuit is connected with the power supply circuit 4.
As an example, the electronic product includes the power supply circuit 4 and the power supply protection circuit in the above example; the input end of the power protection circuit is used for being connected with the power supply 3, and the output end of the protection circuit is connected with the power circuit 4. When the power supply 3 is connected to the electronic product, the power supply voltage VIN is input to the voltage protection circuit 1, the voltage protection circuit 1 detects the power supply voltage VIN, when the power supply voltage VIN is abnormal, the voltage protection circuit 1 is turned off, the power supply circuit 4 has no voltage input, and the power supply circuit 4 is protected from being damaged by abnormal voltage. When the supply voltage VIN is greater than the second reference voltage and less than the first reference voltage, the voltage protection circuit 1 can be smoothly turned on, the supply power 3 supplies power to the power supply circuit 4 in the electronic product, and when the supply voltage VIN is equal to the second reference voltage or the first reference voltage, the voltage protection circuit 1 is in a critical state, and is turned on or off at the previous moment.
In the example, by arranging the voltage protection circuit 1 and the reverse connection preventing circuit 2, when the power supply 3 is reversely connected, the input of the power supply voltage VIN can be cut off, and the protection is formed for the rear reverse connection preventing circuit 2 and the power supply circuit 4; when the power supply voltage VIN is not in the reference voltage range, the input of the power supply voltage VIN can be cut off in time, the power supply circuit 4 of the later stage is further protected, and the safe operation of the power supply circuit 4 is ensured.
The above embodiments are only for illustrating the technical solution of the present utility model, and not for limiting the same; although the utility model has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present utility model, and are intended to be included in the scope of the present utility model.