CN215009573U - Power supply overvoltage protection circuit - Google Patents
Power supply overvoltage protection circuit Download PDFInfo
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- CN215009573U CN215009573U CN202120859798.0U CN202120859798U CN215009573U CN 215009573 U CN215009573 U CN 215009573U CN 202120859798 U CN202120859798 U CN 202120859798U CN 215009573 U CN215009573 U CN 215009573U
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Abstract
The utility model relates to a circuit field especially relates to a power supply overvoltage protection circuit, include: the clamping circuit is connected with the power supply voltage input end and outputs clamping voltage; the voltage division sampling circuit is connected with the power supply voltage input end and is used for carrying out voltage division sampling on the voltage input by the power supply voltage input end and outputting a sampling voltage; the two input ends of the comparator are respectively connected with the output end of the clamping circuit and the output end of the partial pressure sampling circuit, and the comparator is used for comparing the sampling voltage with the clamping voltage and outputting a comparison signal; and the switch circuit is connected between the power supply voltage input end and the power supply voltage output end, is connected with the output end of the comparator, and is used for connecting or disconnecting the power supply from the power supply voltage input end to the power supply voltage output end according to the comparison signal. The utility model discloses a power supply overvoltage protection circuit can turn off mains voltage's power supply when mains voltage is unstable to form the overvoltage through setting up switch circuit to realize overvoltage protection.
Description
Technical Field
The utility model relates to a circuit field especially relates to a power supply overvoltage protection circuit.
Background
Along with the rapid development of the vehicle industry and the continuous improvement of the living standard of people, the requirements of users on the functions of the vehicle machine are increased day by day, and an intelligent vehicle box is provided under the condition that the vehicle machine is not changed. The intelligent car box is communicated with a car machine through a USB interface connected in the car so as to meet the functions of the car machine such as connection with a 4G network, voice control, a car data recorder, live-action navigation, online music, online video and the like.
However, the electronic and electrical systems in the vehicle are very complex, and the output voltage of the power supply in the vehicle fluctuates or jumps along with the problems of ignition, acceleration, generator interference and the like of the vehicle, so that the voltage of the power supply system in the vehicle is very unstable. When powered devices such as intelligent car box directly access in-car USB interface and obtain the power supply, the overvoltage that mains voltage unstability formed in the car can surpass powered devices such as intelligent car box's operating voltage scope for powered devices such as intelligent car box face severe overvoltage environment, can lead to work unusual even by the damage, and need frequent maintenance change. How to design an overvoltage protection circuit for an in-vehicle power supply is a problem to be solved urgently.
SUMMERY OF THE UTILITY MODEL
In view of the above, a power supply overvoltage protection circuit is proposed that overcomes or at least partially solves the above mentioned problems.
An object of the utility model is to provide a power supply overvoltage protection circuit avoids the overvoltage that the power formed in the car to surpass the operating voltage scope of powered device, makes powered device work unusual or damage.
The utility model discloses a further purpose is when supply voltage gets back to normal scope, and the normal work of powered device is guaranteed to the power supply of automatic intercommunication supply voltage input to supply voltage output.
In order to achieve the above object, the present invention provides a power supply overvoltage protection circuit, including:
the clamping circuit is connected with a power supply voltage input end of the power supply and outputs clamping voltage;
the voltage division sampling circuit is connected with the power supply voltage input end and is used for carrying out voltage division sampling on the voltage input by the power supply voltage input end and outputting a sampling voltage;
the two input ends of the comparator are respectively connected with the output end of the clamping circuit and the output end of the partial pressure sampling circuit, and the comparator is used for comparing the sampling voltage with the clamping voltage and outputting a comparison signal; and
and the switch circuit is connected between the power supply voltage input end and the power supply voltage output end of the power supply, connected with the output end of the comparator and used for connecting or disconnecting the power supply from the power supply voltage input end to the power supply voltage output end according to the comparison signal.
Further, the switching circuit includes a first switching element and a second switching element connected; wherein
The first switch element is connected with the output end of the comparator and is configured to be switched on or switched off in response to the comparison signal, and the second switch element is configured to be switched on or switched off in response to the state of the first switch element so as to switch on or switch off the power supply from the power supply voltage input end to the power supply voltage output end.
Further, the second switching element comprises a PMOS tube; wherein
The source electrode of the PMOS tube is connected with the power supply voltage input end, the drain electrode of the PMOS tube is connected with the power supply voltage output end, and the grid electrode of the PMOS tube is connected with the power supply voltage input end through a first resistor.
Further, the first switching element includes an NPN triode; wherein
The emitter of the NPN triode is grounded, the collector of the NPN triode is connected with the grid of the PMOS tube through the second resistor, and the base of the NPN triode is connected with the output end of the comparator.
The comparator comprises an operational amplifier, wherein the non-inverting input end of the operational amplifier is connected with the output end of the clamping circuit to receive clamping voltage, the inverting input end of the operational amplifier is connected with the output end of the voltage division sampling circuit to receive sampling voltage, the output end of the operational amplifier is connected with the base stage of the NPN triode, and the operational amplifier is configured to compare the sampling voltage with the clamping voltage and output a comparison signal; wherein
When the sampling voltage is higher than the clamping voltage, the comparison signal output by the operational amplifier is at a low level, otherwise, the comparison signal is at a high level.
Further, the clamping circuit comprises a third resistor and a voltage stabilizing diode; wherein
One end of the third resistor is connected with the power supply voltage input end, the other end of the third resistor is connected with the cathode of the voltage stabilizing diode, the cathode of the voltage stabilizing diode is also connected with the non-inverting input end of the operational amplifier, and the anode of the voltage stabilizing diode is grounded;
and the connection point between the third resistor and the voltage stabilizing diode is the output end of the clamping circuit.
Further, the zener diode is configured to cause the clamping voltage to be less than the normal operating voltage of the power supply.
Further, the voltage division sampling circuit comprises a fourth resistor and a fifth resistor; wherein
One end of the fourth resistor is connected with the power supply voltage input end, the other end of the fourth resistor is connected with the inverting input end of the operational amplifier and is simultaneously connected with one end of the fifth resistor, and the other end of the fifth resistor is grounded;
and the connection point between the fourth resistor and the fifth resistor is the output end of the voltage division sampling circuit.
Further, the utility model discloses a power supply overvoltage protection circuit still includes the low pass filter unit, is connected with the output and two inputs of comparator for filtering high frequency interference and electrostatic interference.
Further, the low-pass filtering unit includes:
one end of the first capacitor is connected with one input end of the comparator, and the other end of the first capacitor is grounded;
one end of the second capacitor is connected with the other input end of the comparator, and the other end of the second capacitor is grounded; and
and one end of the third capacitor is connected with the output end of the comparator, and the other end of the third capacitor is grounded.
The utility model discloses a power supply overvoltage protection circuit has low cost, low-power consumption, the reliable and stable characteristics of operation through setting up switch circuit, can realize in time turn-off mains voltage's power supply when mains voltage is unstable to form the overvoltage, avoids mains voltage output's voltage to surpass the operating voltage scope of powered device to realize overvoltage protection.
Further, the utility model discloses a power supply overvoltage protection circuit can also get back to when normal scope at mains voltage, resumes the power supply of mains voltage input to mains voltage output immediately, guarantees that the current-carrying equipment normally works.
The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments thereof, taken in conjunction with the accompanying drawings.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. The same reference numbers in the drawings identify the same or similar elements or components. In the drawings:
fig. 1 is a schematic diagram of a power supply overvoltage protection circuit according to an embodiment of the present invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be 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 disclosure to those skilled in the art.
At present, power receiving equipment such as a vehicle machine externally arranged in a vehicle is directly supplied with power from a USB interface, and along with the problems of ignition, acceleration, generator interference and the like of the vehicle, the output voltage of a power supply in the vehicle fluctuates or jumps, so that overvoltage exceeding the working voltage range of the power receiving equipment such as the vehicle machine externally arranged in the vehicle is formed by the power supply in the vehicle, and the power receiving equipment such as the vehicle machine externally arranged in the vehicle faces a severe overvoltage environment.
To address the above-mentioned shortcomings, one embodiment of the present invention provides a power supply overvoltage protection circuit 100. As shown in fig. 1, the power supply overvoltage protection circuit 100 may generally include: a clamp circuit 200, a divided voltage sampling circuit 300, a comparator 400, and a switch circuit 500. The clamp circuit 200 is connected to a power supply voltage input terminal VCC IN and outputs a clamp voltage V1; the voltage division sampling circuit 300 is connected to the power supply voltage input terminal VCC IN, and is configured to perform voltage division sampling on the voltage input by the power supply voltage input terminal VCC IN and output a sampling voltage V2; two input ends of the comparator 400 are respectively connected with the output end of the clamping circuit 200 and the output end of the voltage division sampling circuit 300, and the comparator 400 is used for comparing the sampling voltage V2 with the clamping voltage V1 and outputting a comparison signal; the switch circuit 500 is connected between the supply voltage input terminal VCC IN and the supply voltage output terminal VCC OUT and connected to the output terminal of the comparator 400, and is configured to turn on or off the power supply from the supply voltage input terminal VCC IN to the supply voltage output terminal VCC OUT according to the comparison signal. The power supply of this embodiment can be the USB interface IN the vehicle, and the USB interface IN the vehicle is inserted to the mains voltage input terminal VCC IN of this embodiment, obtains the power supply from this USB interface, and external receiving equipment such as car machine IN the connection vehicle again via mains voltage output terminal VCC OUT to the protection to USB supply circuit IN the vehicle is realized.
The utility model discloses power supply overvoltage protection circuit 100 utilizes clamping circuit 200, partial pressure sampling circuit 300, switch circuit 500 and comparator 400, realized when the voltage of the interior power supply of car when appearing jumps or the unstable problem of mains voltage such as undulant, in time cut off the power supply of interior power supply to external vehicle such as in the vehicle powered device, avoid surpassing the operating voltage scope of powered device because of the overvoltage that the interior power supply of car produced to realize the overvoltage protection to powered device.
In some embodiments, as shown in fig. 1, the power supply overvoltage protection circuit 100 of the present embodiment further includes a low pass filter unit 600. The low pass filter unit 600 is connected to two input terminals and one output terminal of the comparator 400, and is used for filtering out high frequency interference and electrostatic interference. The power supply overvoltage protection circuit 100 of the embodiment filters high-frequency interference and electrostatic interference by arranging the low-pass filtering unit 600, prevents circuit malfunction, and avoids signal comparison errors caused by the high-frequency interference and the electrostatic interference, thereby ensuring stable operation of the power supply overvoltage protection circuit 100.
In some embodiments, the low pass filter unit 600 includes a first capacitor C1, a second capacitor C2, and a third capacitor C3. One end of the first capacitor C1 is connected to one input end of the comparator 400, and the other end of the first capacitor C1 is grounded; one end of the second capacitor C2 is connected to the other input end of the comparator 400, and the other end of the second capacitor C2 is grounded; one end of the third capacitor C3 is connected to the output terminal of the comparator 400, and the other end of the third capacitor C3 is grounded. The power supply overvoltage protection circuit 100 of the embodiment filters high-frequency interference and electrostatic interference by respectively connecting two input ends and one output end of the comparator 400 with a capacitor, so that the response accuracy of the comparator 400 is improved, and the working stability of the power supply overvoltage protection circuit 100 is further improved.
In some embodiments, the clamping circuit 200 includes a third resistor R3 and a zener diode D1; one end of the third resistor R3 is connected to the power supply voltage input terminal VCC IN, the other end of the third resistor R3 is connected to the cathode of the zener diode D1, the cathode of the zener diode D1 is further connected to one input terminal (not called as the first input terminal) of the comparator 400, and the anode of the zener diode D1 is grounded; the junction between the third resistor R3 and the zener diode D1 is the output terminal of the clamp circuit 200, and outputs the clamp voltage V1 to the first input terminal of the comparator 400. In this embodiment, the clamp circuit 200 utilizes the characteristic of the zener diode D1, and the voltage of the first input terminal of the comparator 400 is always clamped at the clamp voltage V1 regardless of whether the USB interface power supply in the vehicle is operating normally or is fluctuating or bouncing. For convenience of description, the ratio of the voltage value of the clamp voltage V1 to the voltage value of the normal operating voltage of the in-vehicle power supply is set to α, that is, the voltage value of the clamp voltage V1 is set to α times the voltage value of the normal operating voltage of the in-vehicle power supply. In some more specific embodiments, 0 < α < 1. Preferably, 0.55 < α < 0.75, for example: α is 0.66.
In some embodiments, the divided voltage sampling circuit 300 includes a fourth resistor R4 and a fifth resistor R5; one end of the fourth resistor R4 is connected to the power supply voltage input terminal VCC IN, the other end of the fourth resistor R4 is connected to the other input terminal (not called as the second input terminal) of the comparator 400, and is also connected to one end of the fifth resistor R5, and the other end of the fifth resistor R5 is grounded. The connection point between the fourth resistor R4 and the fifth resistor R5 is the output terminal of the voltage division sampling circuit 300. In this embodiment, the voltage at the connection point between the fourth resistor R4 and the fifth resistor R5 is the sampling voltage V2 output by the divided voltage sampling circuit 300. Therefore, the present invention provides a voltage-dividing sampling circuit 300 that utilizes the fourth resistor R4 and the fifth resistor R5 to realize the voltage-dividing sampling of the power supply voltage input terminal VCC IN. In application, the voltage at the second input terminal of the comparator 400 can be set by adjusting the magnitude relationship between the resistance value of the fourth resistor R4 and the resistance value of the fifth resistor R5.
In some embodiments, the divided voltage sampling circuit 300 specifically adjusts the magnitude relationship between the resistance of the fourth resistor R4 and the resistance of the fifth resistor R5 according to the setting of the clamping voltage V1 to set the sampling voltage V2. For convenience of description, the ratio of the resistance value of the fourth resistor R4 to the resistance value of the fifth resistor R5 is set to β. On the basis of setting the clamp voltage V1 to α times the normal operating voltage of the in-vehicle power supply, the magnitude relationship between the resistance value of the fourth resistor R4 and the resistance value of the fifth resistor R5 is specifically adjusted so that 1 < α (1+ β). Therefore, when the power supply in the vehicle normally works, the sampling voltage V2 is smaller than the clamping voltage V1; when the power supply in the vehicle fluctuates or jumps, the voltage of the power supply in the vehicle is far higher than the normal working voltage, and the sampling voltage V2 is also far higher than the clamping voltage V1.
In some embodiments, the comparator 400 is an operational amplifier U1, the non-inverting input of the operational amplifier U1 is a first input of the comparator 400, the inverting input of the operational amplifier U1 is a second input of the comparator 400, the output of the operational amplifier U1 is an output of the comparator 400, the non-inverting input of the operational amplifier U1 is connected to the output of the clamp circuit 200 to receive the clamp voltage V1, the inverting input of the operational amplifier U1 is connected to the output of the divided-voltage sampling circuit 300 to receive the sample voltage V2, and the output of the operational amplifier U1 is connected to the switch circuit 500. The operational amplifier U1 is configured to compare the sampled voltage V2 with the clamped voltage V1 and output a comparison signal. When the sampling voltage V2 is higher than the clamp voltage V1, i.e., the voltage at the inverting input terminal of the operational amplifier U1 is higher than the voltage at the non-inverting input terminal of the operational amplifier U1, the comparison signal output by the operational amplifier U1 is at low level, otherwise, the comparison signal is at high level. The power supply overvoltage protection circuit 100 of the present embodiment has a fast response speed by selecting the comparator 400 as the operational amplifier U1, and can quickly complete the comparison between the sampling voltage V2 and the clamping voltage V1 at about 10 μ s.
In some embodiments, the maximum operating voltage of the operational amplifier U1 is higher than the highest possible voltage of the in-vehicle power supply voltage to prevent the operational amplifier U1 from being damaged by the overvoltage generated when the in-vehicle power supply fluctuates or jumps. Specifically, the operational amplifier U1 of the present embodiment may select models of TS321QDBVRQ1, OPA171-Q1, and the like.
In some embodiments, the switching circuit 500 includes a first switching element 510 and a second switching element 520 connected; wherein the first switching element 510 is connected to the output terminal of the comparator 400 and is configured to be turned on or off IN response to the comparison signal, and the second switching element 520 is configured to be turned on or off IN response to the state of the first switching element 510 (i.e., the on or off state of the first switching element 510) to turn on or off the supply of the supply voltage input terminal VCC IN to the supply voltage output terminal VCC OUT. IN some more specific embodiments, when the comparison signal output by the comparator 400 is at a low level, the first switching element 510 is turned off IN response to the low level signal, and the second switching element 520 is turned off IN response to a state IN which the first switching element 510 is turned off, so as to turn off the power supply from the supply voltage input terminal VCC IN to the supply voltage output terminal VCC OUT; when the comparison signal outputted from the comparator 400 is at a high level, the first switching element 510 is turned on IN response to the high level signal, and the second switching element 520 is turned on IN response to the on state of the first switching element 510, so as to connect the power supply from the power supply voltage input terminal VCC IN to the power supply voltage output terminal VCC OUT. The power supply overvoltage protection circuit 100 of this embodiment can accurately control the connection or disconnection of power supply between the power supply voltage input terminal VCC IN and the power supply voltage output terminal VCC OUT by setting the two switching elements of the first switching element 510 and the second switching element 520, thereby controlling the connection or disconnection of power supply between the USB interface IN the vehicle and the power receiving devices such as the IN-vehicle and external devices IN the vehicle, and providing more accurate overvoltage protection for the power receiving devices.
In some more specific embodiments, the first switching element 510 is an NPN transistor Q1, and the second switching element 520 is a PMOS transistor Q2. The base electrode of the NPN triode Q1 is connected with the output end of the operational amplifier U1, the emitter electrode of the NPN triode Q1 is grounded, the collector electrode of the NPN triode Q1 is connected with the grid electrode of the PMOS tube Q2 through the second resistor R2, the connection point of the grid electrode of the PMOS tube Q2 and the second resistor R2 is further connected with a power supply voltage input end VCC IN through the first resistor R1, the source electrode of the PMOS tube Q2 is connected with the power supply voltage input end VCC IN, and the drain electrode of the PMOS tube Q2 is connected with the power supply voltage output end VCC OUT.
Based on the power supply overvoltage protection circuit provided by the preferred embodiment, when the power supply in the vehicle fluctuates or jumps, the voltage of the power supply in the vehicle is far higher than the normal working voltage, and the sampling voltage V2 is also far higher than the clamping voltage V1, that is, the voltage value of the inverting input terminal of the operational amplifier U1 is greater than the voltage value of the non-inverting input terminal of the operational amplifier U1, so that the comparison signal output by the operational amplifier U1 is at a low level. At this time, when no current flows through the base of the NPN transistor Q1, the NPN transistor Q1 is turned off. At this time, no current flows through the first resistor R1 and the second resistor R2, the voltage value of the power supply voltage input terminal VCC IN acts on the gate of the PMOS transistor Q2 without voltage division, the voltage of the gate of the PMOS transistor Q2 is pulled up, the PMOS transistor Q2 is turned off, and the power supply from the power supply voltage input terminal VCC IN to the power supply voltage output terminal VCC OUT is turned off, so that the power supply from the IN-vehicle power supply to the power receiving device is turned off, and the power receiving device is protected from overvoltage damage.
Based on the power supply overvoltage protection circuit provided by the preferred embodiment, when the power supply in the vehicle normally operates, the sampling voltage V2 is lower than the clamping voltage V1, that is, the voltage value of the inverting input terminal of the operational amplifier U1 is smaller than the voltage value of the non-inverting input terminal of the operational amplifier U1, so that the comparison signal output by the operational amplifier U1 is at a high level. At this time, the voltage at the base of NPN transistor Q1 is sufficient to turn on, and NPN transistor Q1 turns on. At this time, current flows through the first resistor R1 and the second resistor R2, the voltage value of the power supply voltage input terminal VCC IN is partially divided by the first resistor R1 and then acts on the gate of the PMOS transistor Q2, the voltage of the gate of the PMOS transistor Q2 is pulled down, the PMOS transistor Q2 is turned on, and the power supply from the power supply voltage input terminal VCC IN to the power supply voltage output terminal VCC OUT is connected, so that the power supply from the IN-vehicle power supply to the power receiving device is connected, and the circuit returns to normal operation.
In some more specific embodiments, the non-inverting input of the operational amplifier U1 is connected to one end of the first capacitor C1, and the other end of the first capacitor C1 is connected to ground; the inverting input end of the operational amplifier U1 is connected with one end of a second capacitor C2, and the other end of the second capacitor C2 is grounded; the output end of the operational amplifier U1 is connected to one end of the third capacitor C3, and the other end of the third capacitor C3 is grounded. In the power supply overvoltage protection circuit 100 of the embodiment, the non-inverting input terminal, the inverting input terminal and the output terminal of the operational amplifier U1 are respectively connected with a capacitor to filter out high-frequency interference and electrostatic interference, so that the response accuracy of the operational amplifier U1 is improved, and the working stability of the power supply overvoltage protection circuit 100 is further improved.
Based on the scheme provided by the embodiment of the utility model, the circuit can be turned off in time when the power supply in the vehicle generates overvoltage along with the problems of vehicle ignition, acceleration or generator interference, so as to protect the power receiving equipment; and the power supply can be automatically recovered after the overvoltage of the power supply in the vehicle disappears, so that the normal power supply to the power receiving equipment is immediately recovered.
IN some embodiments, when the USB interface power supply IN the vehicle normally operates, the output voltage of the USB interface power supply is 5V, and at this time, the voltage of the power supply voltage input terminal VCC IN is 5V; when the ignition, acceleration, generator interference and other problems occur in the vehicle, various power supplies in the vehicle, including the USB interface power supply, will cause power supply fluctuation or jump, and the voltage value of the formed overvoltage may be much larger than 5V.
In this embodiment, the clamping circuit 200 utilizes the characteristic of the zener diode D1 to clamp the voltage at the non-inverting input terminal of the operational amplifier U1 within a range smaller than the power supply voltage of the in-vehicle USB interface. For example, the clamp circuit 200 utilizes the characteristic of the zener diode D1 to clamp the voltage at the non-inverting input terminal of the operational amplifier U1 to 0V to 5V, and more preferably to 2V to 4.5V, such as 3.3V. That is, the voltage of the non-inverting input terminal of the operational amplifier U1 is always controlled to the clamp voltage V1 and set by the clamp circuit 200 regardless of whether the USB interface power supply in the vehicle is operating normally or fluctuating or jumping.
In this embodiment, the divided voltage sampling circuit 300 uses the fourth resistor R4 and the fifth resistor R5 to sample the divided voltage of the USB interface power supply in the vehicle, and by adjusting the magnitude relationship between the resistance value of the fourth resistor R4 and the resistance value of the fifth resistor R5, the voltage value of the inverting input terminal of the operational amplifier U1 during the normal operation of the USB interface power supply in the vehicle can be set. In some more specific embodiments, the divided voltage sampling circuit 300 specifically adjusts the magnitude relationship between the resistance of the fourth resistor R4 and the resistance of the fifth resistor R5 according to the setting of the clamped voltage V1 to set the sampled voltage V2. Preferably, the fourth resistor R4 and the fifth resistor R5 are set such that the resistance of the fourth resistor R4 is 0.52 to 0.63 times the resistance of the fifth resistor R5. More preferably, the fourth resistor R4 and the fifth resistor R5 are set such that the resistance of the fourth resistor R4 is 0.55 to 0.6 times the resistance of the fifth resistor R5. For example: the fourth resistor R4 and the fifth resistor R5 are set to have the resistance value of the fourth resistor R4 0.575 times that of the fifth resistor R5, when the in-vehicle USB interface power supply normally works and the output voltage is 5V, the voltage value of the inverting input terminal of the operational amplifier U1 is 5V ÷ (1+0.575) ≈ 3.175V < 3.3V, that is, the voltage value of the inverting input terminal of the operational amplifier U1 is smaller than the voltage value of the non-inverting input terminal of the operational amplifier U1, and at this time, the operational amplifier outputs a high level; when the USB interface power supply in the vehicle fluctuates or jumps, the voltage value of the USB interface power supply voltage is far greater than 5V, so that the voltage value of the inverting input end of the operational amplifier U1 is far greater than 3.3V, the voltage value of the inverting input end of the operational amplifier U1 is far greater than the voltage value of the non-inverting input end of the operational amplifier U1, and the operational amplifier outputs a low level.
Based on the scheme provided by the embodiment of the utility model, the circuit can be turned off in time when the power supply in the vehicle fluctuates or jumps, thereby protecting the powered device; and can also recover by itself after the overvoltage of the power supply in the vehicle disappears, thereby recovering the normal power supply to the powered device immediately. The utility model provides a detection circuitry still has low cost, low-power consumption, protection fast and can automatic recovery's characteristics, is particularly useful for the overvoltage protection of the interior external powered equipment such as car machine of vehicle in the car, generally establishes ties in the car between external powered equipment such as car machine in power output end and the vehicle. And system pressure test verifies, the embodiment of the utility model provides a detection circuitry operation reliable and stable.
In the description provided herein, numerous specific details are set forth. It is understood, however, that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, the disclosed method should not be interpreted as reflecting an intention that: rather, the invention as claimed requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.
Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the claims, any of the claimed embodiments may be used in any combination.
It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The usage of the words first, second and third, etcetera do not indicate any ordering. These words may be interpreted as names.
Thus, it should be appreciated by those skilled in the art that while a number of exemplary embodiments of the invention have been shown and described in detail herein, many other variations and modifications can be made, consistent with the principles of the invention, which are directly determined or derived from the disclosure herein, without departing from the spirit and scope of the invention. Accordingly, the scope of the present invention should be understood and interpreted to cover all such other variations or modifications.
Claims (9)
1. A power supply overvoltage protection circuit, comprising:
the clamping circuit is connected with a power supply voltage input end of the power supply and outputs clamping voltage;
the voltage division sampling circuit is connected with a power supply voltage input end of the power supply, and is used for carrying out voltage division sampling on the voltage input by the power supply voltage input end and outputting a sampling voltage;
the two input ends of the comparator are respectively connected with the output end of the clamping circuit and the output end of the voltage division sampling circuit, and the comparator is used for comparing the sampling voltage with the clamping voltage and outputting a comparison signal; and
the switch circuit is connected between a power supply voltage input end and a power supply voltage output end of the power supply, connected with the output end of the comparator and used for connecting or disconnecting the power supply from the power supply voltage input end to the power supply voltage output end of the power supply according to the comparison signal; wherein
The switching circuit comprises a first switching element and a second switching element which are connected; wherein
The first switch element is connected with the output end of the comparator and is configured to be switched on or switched off in response to the comparison signal, and the second switch element is configured to be switched on or switched off in response to the state of the first switch element so as to switch on or off the power supply from the power supply voltage input end to the power supply voltage output end.
2. The power supply overvoltage protection circuit of claim 1,
the second switching element comprises a PMOS tube; wherein
The source electrode of the PMOS tube is connected with the power supply voltage input end, the drain electrode of the PMOS tube is connected with the power supply voltage output end, and the grid electrode of the PMOS tube is connected with the power supply voltage input end through a first resistor.
3. The power supply overvoltage protection circuit of claim 2,
the first switching element comprises an NPN triode; wherein
The emitter of the NPN triode is grounded, the collector of the NPN triode is connected with the grid of the PMOS tube through a second resistor, and the base of the NPN triode is connected with the output end of the comparator.
4. The power supply overvoltage protection circuit of claim 3,
the comparator comprises an operational amplifier, wherein the non-inverting input end of the operational amplifier is connected with the output end of the clamping circuit to receive the clamping voltage, the inverting input end of the operational amplifier is connected with the output end of the partial voltage sampling circuit to receive the sampling voltage, the output end of the operational amplifier is connected with the base stage of the NPN triode, and the operational amplifier is configured to compare the sampling voltage with the clamping voltage and output the comparison signal; wherein
When the sampling voltage is higher than the clamping voltage, the comparison signal output by the operational amplifier is at a low level, otherwise, the comparison signal is at a high level.
5. The power supply overvoltage protection circuit of claim 4,
the clamping circuit comprises a third resistor and a voltage stabilizing diode; wherein
One end of the third resistor is connected with the power supply voltage input end, the other end of the third resistor is connected with the cathode of the voltage stabilizing diode, the cathode of the voltage stabilizing diode is also connected with the non-inverting input end of the operational amplifier, and the anode of the voltage stabilizing diode is grounded;
and the connection point between the third resistor and the voltage stabilizing diode is the output end of the clamping circuit.
6. The power supply overvoltage protection circuit of claim 5,
the zener diode is configured to cause the clamping voltage to be less than a normal operating voltage of the power supply.
7. The power supply overvoltage protection circuit of claim 4,
the voltage division sampling circuit comprises a fourth resistor and a fifth resistor; wherein
One end of the fourth resistor is connected with the power supply voltage input end, the other end of the fourth resistor is connected with the inverting input end of the operational amplifier and is also connected with one end of the fifth resistor, and the other end of the fifth resistor is grounded;
and a connection point between the fourth resistor and the fifth resistor is an output end of the voltage division sampling circuit.
8. The power supply overvoltage protection circuit of claim 1, further comprising:
and the low-pass filtering unit is connected with the output end and the two input ends of the comparator and is used for filtering high-frequency interference and electrostatic interference.
9. The power supply overvoltage protection circuit of claim 8,
the low-pass filtering unit includes:
one end of the first capacitor is connected with one input end of the comparator, and the other end of the first capacitor is grounded;
one end of the second capacitor is connected with the other input end of the comparator, and the other end of the second capacitor is grounded; and
and one end of the third capacitor is connected with the output end of the comparator, and the other end of the third capacitor is grounded.
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| CN202120859798.0U CN215009573U (en) | 2021-04-25 | 2021-04-25 | Power supply overvoltage protection circuit |
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| CN202120859798.0U CN215009573U (en) | 2021-04-25 | 2021-04-25 | Power supply overvoltage protection circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115268558A (en) * | 2022-08-22 | 2022-11-01 | 苏州智而卓数字科技有限公司 | Voltage and current universal output interface circuit |
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2021
- 2021-04-25 CN CN202120859798.0U patent/CN215009573U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115268558A (en) * | 2022-08-22 | 2022-11-01 | 苏州智而卓数字科技有限公司 | Voltage and current universal output interface circuit |
| CN115268558B (en) * | 2022-08-22 | 2024-03-22 | 苏州智而卓数字科技有限公司 | Universal output interface circuit for voltage and current |
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