CN210744723U - Overvoltage protection circuit - Google Patents
Overvoltage protection circuit Download PDFInfo
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- CN210744723U CN210744723U CN201921440320.3U CN201921440320U CN210744723U CN 210744723 U CN210744723 U CN 210744723U CN 201921440320 U CN201921440320 U CN 201921440320U CN 210744723 U CN210744723 U CN 210744723U
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- amplitude limiting
- power supply
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- overvoltage protection
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Abstract
Disclosed is an overvoltage protection circuit connected between a power supply and a load, the power supply for providing a supply voltage signal, the overvoltage protection circuit comprising: a voltage selection unit providing a reference voltage signal; the comparison unit is connected with the power supply and the voltage selection unit, receives the power supply voltage signal and the reference voltage signal, and generates a control signal after comparison; the amplitude limiting unit is connected between the comparison unit and the switching tube, carries out amplitude limiting on the control signal and provides an amplitude limiting control signal for the switching tube; and the first path end and the second path end of the switch tube are respectively connected with the power supply and the load, and the control end of the switch tube is connected with the amplitude limiting unit, receives the amplitude limiting control signal and switches on or off the current path according to the amplitude limiting control signal. The overvoltage protection circuit can timely turn off a current path when the power supply voltage is large, and provides overvoltage protection for a rear-stage circuit.
Description
Technical Field
The utility model relates to an electronic power technology, in particular to overvoltage protection circuit.
Background
In electronic product design, for example, new product development, multiple stages of trial-and-error testing are usually performed. Taking the display device as an example, in an Engineering Verification Test (EVT) Test of a middle-sized display device, a power supply is often required to provide an external voltage for testing, and the power supply is connected to a display panel and a large-sized printed circuit board to supply power to the large-sized printed circuit board. Common tests include logic voltage tests (allowable voltage range between 3.3V-3.6V), LED backlight voltage tests (allowable voltage range between 5V-21V), and the like. At present, when the Power supply is used for carrying out voltage coarse adjustment, adjustment is mostly carried out through a knob, input voltage is often overlarge due to the fact that the amplitude of the knob is artificially rotated, damage is caused to an integrated Power chip (Power IC) and an LED driver on a circuit board, and then the display panel is enabled to display abnormity, and the test effect cannot be achieved.
SUMMERY OF THE UTILITY MODEL
In view of this, the utility model aims at providing an overvoltage crowbar can in time cut off the current path when the voltage that power supply provided is great, guarantees that the rear end load is not influenced, plays the effect of protection back stage circuit to solve the problem among the prior art.
According to the utility model provides an overvoltage crowbar connects between power supply and load, power supply is used for providing the supply voltage signal, a serial communication port, overvoltage crowbar includes:
a voltage selection unit providing a reference voltage signal;
the comparison unit is connected with the power supply and the voltage selection unit, receives the power supply voltage signal and the reference voltage signal, and generates a control signal after comparison;
the amplitude limiting unit is connected between the comparison unit and the switching tube, carries out amplitude limiting on the control signal and provides an amplitude limiting control signal for the switching tube; and
and the first path end and the second path end of the switch tube are respectively connected with the power supply and the load, and the control end of the switch tube is connected with the amplitude limiting unit, receives the amplitude limiting control signal and switches on or off the current path according to the amplitude limiting control signal.
Preferably, the voltage selection unit provides the reference voltage signal with adjustable voltage for the comparison unit.
Preferably, the voltage selection unit comprises a BOOST voltage BOOST circuit, and the voltage of the reference voltage signal is adjusted through an internal sliding rheostat.
Preferably, the voltage selection unit includes a plurality of power supplies controlled to be turned on by the selection switch.
Preferably, the comparing unit includes:
the first end of the first resistor is connected to the power supply;
a second resistor, a first end of the second resistor being connected to the voltage selection unit;
and the inverting input end of the single-limit comparator is grounded, the positive input end of the single-limit comparator is respectively connected with the second end of the first resistor and the second end of the second resistor to form a first node, and the output end of the single-limit comparator outputs the control signal.
Preferably, the comparison unit further comprises a third resistor connected between the one-limit comparator and the switching tube.
Preferably, when the positive input end of the single-limit comparator receives a positive voltage, the voltage of the control signal output by the output end of the single-limit comparator is a positive voltage, and the switching tube is controlled to be switched off; when the positive input end of the single-limit comparator receives negative voltage, the voltage of the control signal output by the output end of the single-limit comparator is negative voltage, and the switching tube is controlled to be conducted.
Preferably, the clipping unit includes:
the cathode of the first amplitude limiting voltage-regulator tube is connected to a second node between the comparison unit and the switch tube, and the anode of the first amplitude limiting voltage-regulator tube is connected with a second amplitude limiting voltage-regulator tube;
and the anode of the second amplitude limiting voltage-stabilizing tube is connected to the anode of the first amplitude limiting voltage-stabilizing tube, and the cathode of the second amplitude limiting voltage-stabilizing tube is grounded.
Preferably, the clipping unit clips the control signal to generate a clipping control signal, and a voltage of the clipping control signal ranges from-5V to + 5V.
Preferably, the switch tube comprises a PMOS tube.
The utility model provides an overvoltage protection circuit provides a reference voltage signal for the predetermined threshold voltage of sign, with reference voltage signal and the common input comparison unit of the supply voltage signal that power supply provided, comparison unit exports a control signal according to the operation, switches on or cuts off the switch tube according to control signal, reaches the effect of switching on or cutting off the current route; when the power supply signal provided by the power supply exceeds the preset threshold voltage, a control signal for stopping the switching tube is output, so that the effect of protecting the rear-stage circuit is achieved.
The overvoltage protection circuit is provided with a voltage selection module for providing an adjustable reference voltage signal, so that the overvoltage protection circuit can be suitable for the protection of the rear-stage circuit in different voltage ranges.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings.
Fig. 1 shows a schematic block diagram of an overvoltage protection circuit according to an embodiment of the invention.
Fig. 2 shows a schematic circuit diagram of an overvoltage protection circuit according to an embodiment of the invention.
Fig. 3a and 3b show a schematic circuit diagram of an overvoltage protection circuit according to an embodiment of the present invention and a waveform diagram on an oscilloscope, respectively.
Fig. 4a and 4b show a schematic circuit diagram of an overvoltage protection circuit according to another embodiment of the present invention and a waveform diagram on an oscilloscope, respectively.
Detailed Description
The present invention will be described below based on examples, but the present invention is not limited to only these examples. In the following detailed description of the present invention, certain specific details are set forth. It will be apparent to one skilled in the art that the present invention may be practiced without these specific details. Well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present invention.
It will be understood that when an element is referred to as being "coupled" or "connected" to another element, it can be directly coupled or connected to the other element or intervening elements may be present, and the connection between the elements may be physical, logical, or a combination thereof. In contrast, when an element is referred to as being "directly coupled" or "directly connected" to another element, it is intended that there are no intervening elements present. Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is, what is meant is "including, but not limited to". The terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.
Fig. 1 shows a schematic block diagram of an overvoltage protection circuit according to an embodiment of the invention.
As shown in fig. 1, the power supply 110 supplies power to the load 130, performs engineering verification tests, and the like, and in order to implement overvoltage protection of the circuit, an overvoltage protection circuit 120 is disposed between the power supply 110 and the load 130. The overvoltage protection circuit 120 of the present embodiment includes: a voltage selection unit 121, a comparison unit 122, a limiting unit 123 and a switching tube P1.
The power supply 110 is configured to provide a power supply voltage signal Vout, the voltage selection unit 121 is configured to provide a reference voltage signal Vs, and the comparison unit 122 is connected to the power supply 110 and the voltage selection unit 121, respectively, and configured to receive the power supply voltage signal Vout and the reference voltage signal Vs, and generate a control signal Vcon after comparison; the amplitude limiting unit 123 is connected between the comparing unit 122 and the switching tube P1, and is configured to perform amplitude limiting on the control signal Vcon and provide an amplitude limiting control signal Vlim to the switching tube P1; the first path end and the second path end of the switching tube P1 are respectively connected to the power supply 110 and the load 130, and the control end is connected to the amplitude limiting unit 123, and is configured to receive the amplitude limiting control signal Vlim and turn on or off the current path according to the amplitude limiting control signal Vlim.
The reference voltage signal Vs provided by the voltage selection unit 121 is used to represent a preset threshold voltage Vt, and the threshold voltage Vt can be obtained by performing a series of transformations on the reference voltage signal Vs, so that the voltage value of the reference voltage signal Vs is determined by the preset threshold voltage Vt. When the power supply voltage signal Vout provided by the power supply is smaller than the threshold voltage Vt, the comparing unit 122 compares the power supply voltage signal Vout with the reference voltage signal Vs, and outputs a control signal Vcon, such that the switching transistor P1 is turned on, the current path between the power supply 110 and the load 130 is turned on, and the power supply 110 supplies power to the load 130; when the power supply voltage signal Vout provided by the power supply is greater than the threshold voltage Vt, the circuit protection is required, and at this time, the comparing unit 122 compares the power supply voltage signal Vout with the reference voltage signal Vs, and outputs a control signal Vcon, so that the switching tube P1 is turned off, the current path between the power supply 110 and the load 130 is disconnected, the power supply 110 cannot supply power to the load 130, and the load 130 is protected, where the load 130 is, for example, a printed circuit board or a display panel. This is explained in more detail below in connection with the schematic circuit diagram of fig. 2.
Fig. 2 shows a schematic circuit diagram of an overvoltage protection circuit according to an embodiment of the invention.
In this embodiment, for ease of illustration, power supply 110 is represented by power supply V1 and load 130 is represented by resistor R4.
Since different voltage ranges of the power supply voltage are usually used in the test, and accordingly, the threshold voltage Vt needs to be set to different values in different tests, the voltage selecting unit 121 of this embodiment can provide the reference voltage signal Vs with adjustable voltage for the comparing unit 122. The voltage selection unit 121 may be implemented by a BOOST circuit, and a sliding rheostat is connected in series to a feedback resistor inside the BOOST circuit to regulate the sliding rheostat to implement regulation of the reference voltage signal Vs. The voltage selection unit 121 of the present embodiment may further include a plurality of power supplies controlled to be turned on by a selection switch, and as shown in fig. 3a and 4a, different power supplies are switched by the selection switch (for example, a single-pole double-throw switch or a single-pole multi-throw switch) to generate the reference voltage signal Vs with different voltage values.
The comparing unit 122 of the present embodiment includes: the circuit comprises a first resistor R1, a second resistor R2 and a single-limit comparator U1, wherein a first end of the first resistor R1 is connected to a power supply end of a power supply V1, and a second end of the first resistor R1 is connected to a positive input end (pin 4) of the single-limit comparator U1; a first terminal of the second resistor R2 is connected to the output terminal of the voltage selection unit 121, and a second terminal is also connected to the positive input terminal of the one-way comparator U1, as shown in fig. 2, and second terminals of the first resistor R1 and the second resistor R2 are both connected to the first node Q1. The inverting input terminal (pin 5) of the single-limit comparator U1 is grounded, the output terminal (pin 1) outputs a control signal Vcon, and the first power input terminal (pin 2) and the second power input terminal (pin 3) are respectively connected to the system voltage VDD and the system voltage VEE. The comparing unit 122 further includes a third resistor R3 connected between the one-way comparator U1 and the switching tube P1.
The amplitude limiting unit 123 comprises a first amplitude limiting voltage regulator tube D1 and a second amplitude limiting voltage regulator tube D2, the cathode of the first amplitude limiting voltage regulator tube D1 is connected to a second node Q2 between the comparison unit 123 and the switch tube P1, and the anode of the first amplitude limiting voltage regulator tube D2; the anode of the second amplitude limiting regulator tube D2 is connected to the anode of the first amplitude limiting regulator tube D1, and the cathode is grounded. The amplitude limiting unit 123 limits the amplitude of the control signal Vcon to generate an amplitude limiting control signal Vlim, and controls the voltage range of the amplitude limiting control signal Vlim output to the control end of the switching tube P1 to be between-5V and + 5V.
In this embodiment, the switch transistor includes, for example, a PMOS transistor, a gate of which is connected to the resistor R3 for receiving the clipping control signal Vlim, a source of which is connected to the power supply V1, and a drain of which is connected to the load R4.
The one-way comparator U1 uses ground as a reference voltage when the negative input terminal is grounded due to its own characteristics, so when the voltage input from the positive input terminal is greater than zero, the voltage at the output terminal is positive, and when the voltage input from the positive input terminal is less than zero, the voltage output from the output terminal is negative. And due to the conduction characteristic of the PMOS tube, when the voltage received by the grid electrode is negative, the PMOS tube is conducted to connect the current path, and when the voltage received by the grid electrode is positive, the PMOS tube is cut off to disconnect the current path. In the present embodiment, the characteristics of the above elements are fully utilized, so when the positive input terminal 4 of the one-way comparator U1 receives a positive voltage, the voltage of the control signal Vcon output from the output terminal 1 is a positive voltage, and the control switch P1 is turned off; when the positive input end 4 of the one-way comparator receives a negative voltage, the voltage of the control signal Vcon output by the output end 5 is a negative voltage, and the control switch tube P1 is turned on.
Since the first resistor R1 and the second resistor R2 are actually connected in parallel to the positive input terminal of the one-way comparator U1, the two input voltages are actually combined and compared with the ground reference voltage. Moreover, the reference voltage signal Vs provided by the voltage selection unit 121 is a negative polarity voltage, and the voltage output by the power supply V1 is a positive voltage, so it can be considered as comparing the absolute value of the voltage value of the supply voltage signal Vout with the absolute value of the voltage value of the reference voltage signal Vs, when the absolute value of the voltage value of the supply voltage signal Vout is greater than the absolute value of the voltage value of the reference voltage signal Vs, the one-way comparator U1 outputs a positive voltage signal, so that the switching tube P1 is turned off, and the current path is opened, i.e. when the voltage provided by the power supply V1 is too large, the circuit overvoltage protection is required.
In this embodiment, the first resistor R1 to the fourth resistor R4 may have the same resistance, for example, 1.0k Ω, the system voltage VDD is 5V, and the system voltage VEE is-5V. The switching tube P1 employs an IRF9130 element.
The reference voltage signal Vs is used to characterize the threshold voltage Vt, and the relationship can be expressed by a formula, for example
This is again depicted in fig. 3a and 3 b. The description of the parameters and formulas in this embodiment is only an example, and is not intended to limit the present invention.
Fig. 3a and 3b show a schematic circuit diagram of an overvoltage protection circuit according to an embodiment of the present invention and a waveform diagram on an oscilloscope, respectively.
As shown in fig. 3a, the voltage selecting unit 121 includes two power supplies (a power supply V2 and a power supply V3) respectively connected to the single-pole double-throw switch S1, wherein the power supply V2 is-12.55V, and the power supply V3 is-3.55V. In this embodiment, the voltage of the power supply voltage signal Vout provided by the power supply V1 is 3.3V, so the switch S1 is connected to the power supply V3, and the reference voltage signal Vs is-3.55V, so the power supply voltage signal Vout and the reference voltage signal Vs are respectively input to the same input terminal 4 of the one-limit comparator U1 through the first resistor R1 and the second resistor R2, the power supply voltage signal Vout is smaller than the threshold voltage Vt, and the voltage received by the same-direction input terminal is a negative voltage, so the switch P1 is turned on.
The voltage detection is carried out by an oscilloscope, the channel A is respectively connected with the grid of the switch tube P1, the channel B is respectively connected with the ground and the drain of the switch tube P1, therefore, the channels A and B respectively detect the grid voltage and the drain voltage of the switch tube P1 and judge whether the switch tube P1 is conducted or not.
Referring to fig. 3B, the data and waveform shown on the oscilloscope show that the voltage detected by the channel a is-5.912V, and the voltage detected by the channel B is 3.299V, so that the switch P1 is turned on, and the voltages of the two pass terminals (source and drain) of the switch P1 are almost the same, which conforms to the circuit design.
The clipping unit 123 can control the voltage value of the clipping control signal Vlim between-5V and +5V, but since the switch tube P1 itself has a conduction voltage drop, the absolute value of the voltage detected by the channel a of the oscilloscope is greater than 5V.
Fig. 4a and 4b show a schematic circuit diagram of an overvoltage protection circuit according to another embodiment of the present invention and a waveform diagram on an oscilloscope, respectively.
Fig. 4a is the same as the circuit connection of fig. 3a, and is not repeated, except that the voltage value of the power supply voltage signal Vout is changed to 3.6V, the voltage of the reference voltage signal Vs is still-3.55V, the power supply voltage signal Vout and the reference voltage signal Vs are respectively input to the same input terminal 4 of the one-way comparator U1 through the first resistor R1 and the second resistor R2, the power supply voltage signal Vout is greater than the threshold voltage Vt, and the voltage received by the same-direction input terminal is a positive voltage, so the switch tube P1 is turned off, and the current path is turned off.
The voltage detection is carried out by an oscilloscope, the channel A is respectively connected with the grid of the switch tube P1, the channel B is respectively connected with the ground and the drain of the switch tube P1, therefore, the channels A and B respectively detect the grid voltage and the drain voltage of the switch tube P1 and judge whether the switch tube P1 is conducted or not.
Referring to fig. 4B, data and a waveform diagram displayed on the oscilloscope show that the voltage detected by the channel a is 5.838V, the clipping control signal Vlim output by the clipping unit 123 is a positive voltage, and the voltage detected by the channel B is 3.596mV, which is almost zero, so that the switching tube P1 is turned off, and the voltage difference between the two pass terminals (source and drain) of the switching tube P1 is large, so as to protect the rear-stage circuit, and meet the circuit design.
The utility model provides an overvoltage protection circuit provides a reference voltage signal for the predetermined threshold voltage of sign, with reference voltage signal and the common input comparison unit of the supply voltage signal that power supply provided, comparison unit exports a control signal according to the operation, switches on or cuts off the switch tube according to control signal, reaches the effect of switching on or cutting off the current route; when the power supply signal provided by the power supply exceeds the preset threshold voltage, a control signal for stopping the switching tube is output, so that the effect of protecting the rear-stage circuit is achieved. And the overvoltage protection circuit is provided with a voltage selection module for providing an adjustable reference voltage signal, so that the overvoltage protection circuit can be suitable for the protection of the rear-stage circuit in different voltage ranges.
As can be known from experiments, when the power supply voltage Vout provided by the power supply 110 is too large, for example, exceeds the predetermined threshold voltage Vt, the overvoltage protection circuit of the embodiment outputs a limiting control signal Vlim, so that the switching tube P1 is turned off, and the current path between the power supply 110 and the load 130 is turned off, thereby protecting the subsequent circuit.
Finally, it should be noted that: in accordance with the embodiments of the present invention as set forth above, these embodiments are not exhaustive and do not limit the invention to the precise embodiments described. Obviously, many modifications and variations are possible in light of the above teaching. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included within the protection scope of the present invention. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and its practical application in conjunction with the modifications made to the invention. The present invention is limited only by the claims and their full scope and equivalents.
Claims (10)
1. An overvoltage protection circuit connected between a power supply and a load, the power supply for providing a supply voltage signal, the overvoltage protection circuit comprising:
a voltage selection unit providing a reference voltage signal;
the comparison unit is connected with the power supply and the voltage selection unit, receives the power supply voltage signal and the reference voltage signal, and generates a control signal after comparison;
the amplitude limiting unit is connected between the comparison unit and the switching tube, carries out amplitude limiting on the control signal and provides an amplitude limiting control signal for the switching tube; and
and the first path end and the second path end of the switch tube are respectively connected with the power supply and the load, and the control end of the switch tube is connected with the amplitude limiting unit, receives the amplitude limiting control signal and switches on or off the current path according to the amplitude limiting control signal.
2. The overvoltage protection circuit of claim 1, wherein the voltage selection unit provides the reference voltage signal with an adjustable voltage to the comparison unit.
3. The overvoltage protection circuit of claim 2, wherein the voltage selection unit comprises a BOOST circuit, the voltage of the reference voltage signal being regulated by an internal sliding varistor.
4. The overvoltage protection circuit of claim 2, wherein the voltage selection unit comprises a plurality of power supplies that are gated by a selection switch control.
5. The overvoltage protection circuit of claim 1, wherein the comparison unit comprises:
the first end of the first resistor is connected to the power supply;
a second resistor, a first end of the second resistor being connected to the voltage selection unit;
and the inverting input end of the single-limit comparator is grounded, the positive input end of the single-limit comparator is respectively connected with the second end of the first resistor and the second end of the second resistor to form a first node, and the output end of the single-limit comparator outputs the control signal.
6. The overvoltage protection circuit of claim 5, wherein the comparison unit further comprises a third resistor connected between the one-way comparator and the switching tube.
7. The overvoltage protection circuit according to claim 5, wherein when the positive input terminal of the one-way comparator receives a positive voltage, the voltage of the control signal output by the output terminal is a positive voltage, and the switching tube is controlled to be turned off; when the positive input end of the single-limit comparator receives negative voltage, the voltage of the control signal output by the output end of the single-limit comparator is negative voltage, and the switching tube is controlled to be conducted.
8. The overvoltage protection circuit of claim 1, wherein the clipping unit comprises:
the cathode of the first amplitude limiting voltage-regulator tube is connected to a second node between the comparison unit and the switch tube, and the anode of the first amplitude limiting voltage-regulator tube is connected with a second amplitude limiting voltage-regulator tube;
and the anode of the second amplitude limiting voltage-stabilizing tube is connected to the anode of the first amplitude limiting voltage-stabilizing tube, and the cathode of the second amplitude limiting voltage-stabilizing tube is grounded.
9. The overvoltage protection circuit of claim 1, wherein the clipping unit clips the control signal to generate a clipping control signal having a voltage range of-5V to + 5V.
10. The overvoltage protection circuit of claim 1, wherein the switch tube comprises a PMOS tube.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921440320.3U CN210744723U (en) | 2019-09-02 | 2019-09-02 | Overvoltage protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921440320.3U CN210744723U (en) | 2019-09-02 | 2019-09-02 | Overvoltage protection circuit |
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| Publication Number | Publication Date |
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| CN210744723U true CN210744723U (en) | 2020-06-12 |
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| CN201921440320.3U Active CN210744723U (en) | 2019-09-02 | 2019-09-02 | Overvoltage protection circuit |
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| CN (1) | CN210744723U (en) |
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