CN220209957U - Over-temperature and over-voltage protection circuit - Google Patents
Over-temperature and over-voltage protection circuit Download PDFInfo
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- CN220209957U CN220209957U CN202321684238.1U CN202321684238U CN220209957U CN 220209957 U CN220209957 U CN 220209957U CN 202321684238 U CN202321684238 U CN 202321684238U CN 220209957 U CN220209957 U CN 220209957U
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Abstract
The embodiment of the utility model discloses an over-temperature and over-voltage protection circuit, which comprises a voltage stabilizing transistor, a negative temperature coefficient thermistor, an input end, an output end, a first resistor, a first transistor and a second transistor, wherein a first electrode of the first transistor is connected with the input end, a third electrode of the first transistor is connected with the output end, the voltage stabilizing transistor is reversely connected between the input end and the ground, the negative temperature coefficient thermistor is connected between the first electrode and the second electrode of the first transistor, the first electrode of the second transistor is connected with the input end, a second electrode of the second transistor is connected with the negative electrode of the voltage stabilizing transistor, a third electrode of the second transistor is connected with the second end of the negative temperature coefficient thermistor, one end of the first resistor is connected with the second end of the negative temperature coefficient thermistor, and the other end of the first resistor is grounded. The utility model can reduce the cost and the processing time delay. Can be widely applied to the field of electronic circuits.
Description
Technical Field
The utility model relates to the field of electronic circuits, in particular to an over-temperature and over-voltage protection circuit.
Background
Currently, in most power supply systems, an overvoltage protection device or a temperature protection device is mostly arranged to reduce damage to the power supply system caused by power supply fluctuation or internal temperature rise of the system, and even cause potential safety hazard.
The general power protection device acquires the input voltage of the system or the internal temperature of the system through software or a chip, and when the input voltage or the temperature exceeds a threshold value, the input is disconnected to protect a rear-end load connected with an output end; but the implementation cost of the software or the chip is high, and the processing time is prolonged.
Disclosure of Invention
Therefore, an objective of the embodiments of the present utility model is to provide an over-temperature and over-voltage protection circuit, which detects an input voltage and a temperature through hardware, thereby reducing cost and processing time delay.
The embodiment of the utility model provides an over-temperature and over-voltage protection circuit which comprises a voltage stabilizing tube, a negative temperature coefficient thermistor, an input end, an output end, a first resistor, a first transistor and a second transistor, wherein the transistor comprises a triode or a field effect tube;
a first electrode of the first transistor is connected with the input end, and a third electrode of the first transistor is connected with the output end;
the negative electrode of the voltage stabilizing tube is connected with the input end, and the positive electrode of the voltage stabilizing tube is grounded;
the first end of the negative temperature coefficient thermistor is connected with the first electrode of the first transistor, and the second end of the negative temperature coefficient thermistor is connected with the second electrode of the first transistor;
the first electrode of the second transistor is connected with the input end, the second electrode of the second transistor is connected with the negative electrode of the voltage stabilizing tube, and the third electrode of the second transistor is connected with the second end of the negative temperature coefficient thermistor;
one end of the first resistor is connected with the second end of the negative temperature coefficient thermistor, and the other end of the first resistor is grounded.
Further, the circuit further comprises a second resistor, one end of the second resistor is connected with the input end, and the other end of the second resistor is connected with the negative electrode of the voltage stabilizing tube.
Further, the circuit further comprises a third resistor, one end of the third resistor is connected with the negative electrode of the voltage stabilizing tube, and the other end of the third resistor is connected with the second electrode of the second transistor.
Further, the circuit further comprises a capacitor, one end of the capacitor is connected with the input end, and the other end of the capacitor is connected with the third electrode of the second transistor.
Further, when the output voltage range of the output end is 2.8V-3.8V, the resistance range of the first resistor is 1.3KΩ -1.7 Kohm, and the stable voltage range of the voltage stabilizing tube is 3.1V-3.5V.
Further, when the output voltage range of the output end is 4.5V-5.5V, the resistance range of the first resistor is 2.9KΩ -3.3KΩ, and the stable voltage range of the voltage stabilizing tube is 5.4V-5.8V.
Further, when the output voltage value of the output end ranges from 9.5V to 10.5V, the resistance value of the first resistor ranges from 6.5KΩ to 7.5KΩ, and the stable voltage value of the voltage stabilizing tube ranges from 9.8V to 10.2V.
Further, when the output voltage range of the output end is 11.5V-12.5V, the resistance range of the first resistor is 8.5kΩ -9kΩ, and the stable value range of the voltage regulator tube is 11.7V-12.3V.
Further, when the output voltage of the output end ranges from 23.5V to 24.5V, the resistance of the first resistor ranges from 18kΩ to 19kΩ, and the stable value of the voltage stabilizing tube ranges from 23.7V to 24.3V.
Further, when the output voltage of the output end ranges from 27.5V to 28.5V, the resistance of the first resistor ranges from 21KΩ to 22KΩ, and the stable value of the voltage stabilizing tube ranges from 27.7V to 28.3V.
The embodiment of the utility model has the following beneficial effects: the utility model provides an over-temperature and over-voltage protection circuit which comprises a voltage stabilizing tube, a negative temperature coefficient thermistor, an input end, an output end, a first resistor, a first transistor and a second transistor, wherein a first electrode of the first transistor is connected with the input end, and a third electrode of the first transistor is connected with the output end; the negative electrode of the voltage stabilizing tube is connected with the input end, and the positive electrode of the voltage stabilizing tube is grounded; the first end of the negative temperature coefficient thermistor is connected with the first electrode of the first transistor, and the second end of the negative temperature coefficient thermistor is connected with the second electrode of the first transistor; the first electrode of the second transistor is connected with the input end, the second electrode of the second transistor is connected with the negative electrode of the voltage stabilizing tube, and the third electrode of the second transistor is connected with the second end of the negative temperature coefficient thermistor; one end of the first resistor is connected with the second end of the negative temperature coefficient thermistor, and the other end of the first resistor is grounded; when the circuit is in a high temperature environment, the resistance of the negative temperature coefficient thermistor is reduced along with the temperature rise, so that the voltage at the two ends of the negative temperature coefficient thermistor is reduced, the first transistor is in a cut-off state, the connection between the input end and the output end is disconnected, and the over-temperature protection function is realized; when the input voltage of the circuit is high, the voltage stabilizing tube is reversely broken down to generate reverse current, so that the second transistor is in a conducting state, the inter-stage voltage of the first transistor becomes zero, the first transistor is in a cut-off state, the connection between the input end and the output end is disconnected, and an overvoltage protection function is realized; when high temperature and high pressure are simultaneously present, the overvoltage protection function and the overtemperature protection function are simultaneously acted; the embodiment does not use software, but adopts hardware to realize the temperature and voltage detection and protection functions, reduces the realization cost, reduces the processing time delay and has high reliability.
Drawings
FIG. 1 is a schematic circuit diagram provided by an embodiment of the present utility model;
fig. 2 is another schematic circuit diagram provided by an embodiment of the present utility model.
Wherein VIN is an input terminal, VOUT is an output terminal, Q1 is a first transistor, Q2 is a second transistor, RT is a negative temperature coefficient thermistor, R1 is a first resistor, R2 is a second resistor, R3 is a third resistor, D1 is a regulator tube, and C is a capacitor.
Detailed Description
The utility model will now be described in further detail with reference to the drawings and to specific examples.
As shown in fig. 1, an over-temperature and over-voltage protection circuit includes an input terminal VIN, an output terminal VOUT, a voltage regulator D1, a negative temperature coefficient thermistor RT, a first resistor R1, a first transistor Q1, and a second transistor Q2, where the transistors include a triode or a field effect transistor;
specifically, the input end is connected with a power supply to provide working voltage for a system where the circuit is located; the output end is connected with a subsequent load, and the load comprises one or more of a light emitting device and an energy storage element, such as a light emitting diode, an inductance device and the like; the voltage stabilizer works when the input voltage of the input end is high, and the resistance value of the negative temperature coefficient thermistor is reduced along with the rise of temperature; the first resistor has a voltage dividing function, and the resistance value of the first resistor is determined according to the input voltage of the input end and the resistance value of the negative temperature coefficient thermistor; the transistor serves as a switching device that turns on when the voltage exceeds a preset value.
The first electrode of the first transistor is connected to the input terminal, and the third electrode of the first transistor is connected to the output terminal.
Specifically, the first transistor is connected between the input end and the output end, and is conducted when the input voltage of the input end is in a normal working voltage range or the circuit temperature is normal temperature, and the input voltage of the input end is output to a load connected with the output end; when the circuit state is abnormal, the first transistor breaks the connection between the input end and the output end, so that a load connected with the output end is protected, for example, when the input voltage of the input end is high or the circuit temperature is too high, the first transistor is in a cut-off state, and the connection between the input end and the output end is broken; in a specific embodiment, the first transistor may be a field effect transistor.
The negative pole of the voltage-stabilizing tube is connected with the input end, and the positive pole of the voltage-stabilizing tube is grounded.
Specifically, the voltage stabilizing tube is reversely connected between the input end and the ground, and the reverse voltage of the voltage stabilizing tube is the input voltage of the input end; under the normal state, the input voltage of the input end is smaller than the voltage stabilizing value of the voltage stabilizing tube; when the input voltage of the input end exceeds the voltage stabilizing value of the voltage stabilizing tube, the voltage stabilizing tube breaks down to generate reverse current, the voltage at two ends of the voltage stabilizing tube is stabilized at the voltage stabilizing value, so that the first transistor is in a cut-off state, the connection between the input end and the output end is disconnected, and the load connected with the output end is protected.
The first end of the negative temperature coefficient thermistor is connected with the first electrode of the first transistor, and the second end of the negative temperature coefficient thermistor is connected with the second electrode of the first transistor.
Specifically, the negative temperature coefficient thermistor is connected between the first electrode and the second electrode of the first transistor, in a specific embodiment, the first electrode adopts a field effect transistor, the negative temperature coefficient thermistor is connected between the source electrode S and the drain electrode D of the field effect transistor, and the voltage at two ends of the negative temperature coefficient thermistor is the voltage between the source electrode S and the drain electrode D of the field effect transistor; when the circuit temperature is at normal temperature, the resistance value of the negative temperature coefficient thermistor is larger, the voltage between the source and the grid of the field effect transistor is larger than the conducting voltage of the field effect transistor, and the field effect transistor is conducted; the temperature of the circuit is gradually increased, the resistance value of the negative temperature coefficient thermistor is gradually reduced, and therefore, the voltage at the two ends of the negative temperature coefficient thermistor is also gradually reduced until the temperature exceeds a preset value, the voltage at the two ends of the negative temperature coefficient thermistor is smaller than the on voltage of the field effect tube, the field effect tube is in a cut-off state, and the connection between the input end and the output end is disconnected.
The first electrode of the second transistor is connected with the input end, the second electrode of the second transistor is connected with the negative electrode of the voltage stabilizing transistor, and the third electrode of the second transistor is connected with the second end of the negative temperature coefficient thermistor.
Specifically, when the control voltage or the control current of the second electrode of the second transistor is smaller than the on value, the second transistor is in an off state; when the control voltage or the control current of the second electrode of the second transistor is larger than the conduction value, the second transistor is conducted, the source electrode and the grid electrode of the first transistor are in short circuit in the circuit, the voltage between the source electrode and the grid electrode becomes zero, the first transistor is in a cut-off state, and the connection between the input end and the output end is disconnected; in a specific embodiment, the second transistor may employ a triode.
One end of the first resistor is connected with the second end of the negative temperature coefficient thermistor, and the other end of the first resistor is grounded.
Specifically, the first resistor is used as a bias resistor of the negative temperature coefficient thermistor and the first transistor, the resistance value of the first resistor is determined according to the negative temperature coefficient thermistor and the on voltage of the first transistor, and a proper bias voltage is provided for the first transistor to normally work so that the first transistor is at a proper working static working point.
Optionally, the circuit further comprises a second resistor, one end of the second resistor is connected with the input end, and the other end of the second resistor is connected with the negative electrode of the voltage stabilizing tube.
Specifically, the second resistor is used as a series resistor of the voltage stabilizing tube, so that the magnitude of reverse current generated by reverse breakdown of the voltage stabilizing tube is limited, the risk that the reverse current exceeds rated current of the voltage stabilizing tube to cause the voltage stabilizing tube to be burnt out is reduced, and meanwhile, voltage exceeding the voltage stabilizing value of the voltage stabilizing tube is separated, and voltage stabilizing of the voltage stabilizing tube is realized.
Optionally, the circuit further comprises a third resistor, one end of the third resistor is connected with the negative electrode of the voltage stabilizing tube, and the other end of the third resistor is connected with the second electrode of the second transistor.
Specifically, the third resistor is used as a second electrode bias resistor of the second transistor, and provides a small current for the second electrode of the second transistor, namely provides a stable static working point for the second transistor, so that the second transistor can work normally.
Optionally, the circuit further includes a capacitor, one end of the capacitor is connected to the input terminal, and the other end of the capacitor is connected to the third electrode of the second transistor.
Specifically, the capacitor is used for slowing down the reaction speed of the first transistor, when the first transistor is changed from an off state to an on state, the input end is connected with the output end, the input voltage of the input end is directly output to a load connected with the output end, and for the load, the input voltage is added in an instant, so that the load is easy to damage; meanwhile, the capacitor also plays a role in filtering, high-frequency noise in the input signal of the first transistor is isolated, and the risk that the first transistor cannot work normally due to the high-frequency noise is reduced.
Optionally, when the voltage value range of the output end is 2.8V-3.8V, the resistance value range of the first resistor is 1.3kΩ -1.7kΩ, and the stable voltage value range of the voltage stabilizing tube is 3.1-3.5V.
Specifically, in the embodiment, the first resistor and the voltage stabilizing transistor are selected according to the voltage range of the output voltage, when the input voltage range of the input end is 2.8V-3.8V, the first transistor is a P-type field effect transistor with the on voltage of 1.3V, at the normal temperature of 25 ℃, the voltage at two ends of the negative temperature coefficient thermistor exceeds the on voltage of the first transistor, so that the first transistor is fully on, the preset protection temperature is 60 ℃, when the circuit temperature exceeds the preset protection temperature, the source-gate voltage of the first transistor is lower than the on voltage, the first transistor is in the off state, the input end and the output end are disconnected, and protection is realized, therefore, when the circuit temperature exceeds the preset protection temperature, the voltage at two ends of the negative temperature coefficient thermistor is lower than the on voltage of the first transistor, and the resistance value of the negative temperature coefficient thermistor is 1.244kΩ, and the resistance range of the first resistor is ((2.8-1.3) ×1.244K)/1.3=1.3 (((3.8-1.3) =1.3 kΩ)/1.3); the voltage stabilizing tube is selected according to the input voltage of the input end, and in order to ensure the voltage stabilizing effect, the voltage stabilizing value of the voltage stabilizing tube can be 1V-2V higher than the input voltage of the input end, and the voltage stabilizing value range is 3.1-3.5V. In the embodiment of the present utility model, the specific model of each device is not particularly limited.
Optionally, when the voltage value range of the output end is 4.5V-5.5V, the resistance value range of the first resistor is 2.9kΩ -3.3kΩ, and the stable voltage value range of the voltage stabilizing tube is 5.4-5.8V.
Specifically, in a specific embodiment, when the input voltage of the input end is in the range of 4.5V-5.5V, the first transistor is a P-type field effect transistor with a conducting voltage of 1.3V, at normal temperature of 25 ℃, the voltage at two ends of the negative temperature coefficient thermistor exceeds the conducting voltage of the first transistor, so that the first transistor is fully conducted, the preset protection temperature is set to 60 ℃, when the circuit temperature exceeds the preset protection temperature, the voltage between the source and the grid of the first transistor is lower than the conducting voltage, the first transistor is in an off state, and the input end and the output end are disconnected, so that protection is realized, therefore, when the circuit temperature exceeds the preset protection temperature, the voltage at two ends of the negative temperature coefficient thermistor is lower than the conducting voltage of the first transistor, and the resistance value of the negative temperature coefficient thermistor is 1.244kΩ, and the resistance value range of the first resistor is ((4.5-1.3) ×1.244K)/1.3=2.9 kΩ, and ((5.5-1.3) ×1.244=3.3) =3; the voltage stabilizing tube is selected according to the input voltage of the input end, and in order to ensure the voltage stabilizing effect, the voltage stabilizing value of the voltage stabilizing tube can be 1V-2V higher than the input voltage of the input end, and the voltage stabilizing value range is 5.4-5.8V. In the embodiment of the present utility model, the specific model of each device is not particularly limited.
Optionally, when the voltage value of the output end ranges from 9.5V to 10.5V, the resistance value of the first resistor ranges from 6.5kΩ to 7.5kΩ, and the stable voltage value of the voltage stabilizing tube ranges from 9.8V to 10.2V.
Specifically, in a specific embodiment, when the input voltage of the input end is in the range of 9.5V-10.5V, the first transistor is a P-type field effect transistor with a conducting voltage of 1.3V, at normal temperature of 25 ℃, the voltage at two ends of the negative temperature coefficient thermistor exceeds the conducting voltage of the first transistor, so that the first transistor is fully conducted, the preset protection temperature is set to 60 ℃, when the circuit temperature exceeds the preset protection temperature, the voltage between the source and the grid of the first transistor is lower than the conducting voltage, the first transistor is in an off state, and the input end and the output end are disconnected, so that protection is realized, therefore, when the circuit temperature exceeds the preset protection temperature, the voltage at two ends of the negative temperature coefficient thermistor is lower than the conducting voltage of the first transistor, and the resistance of the negative temperature coefficient thermistor is reduced to 1.244kΩ, and then the resistance range of the first resistor is ((9.5-1.3) ×1.244K)/1.3=6.5 kΩ, and ((10.5-1.3) ×1.244) =1.7.5 kΩ; the voltage stabilizing tube is selected according to the input voltage of the input end, and in order to ensure the voltage stabilizing effect, the voltage stabilizing value of the voltage stabilizing tube can be 1V-2V higher than the input voltage of the input end, and the voltage stabilizing value range of the selected voltage stabilizer is 9.8-10.2V. In the embodiment of the present utility model, the specific model of each device is not particularly limited.
Optionally, when the voltage value of the output end ranges from 11.5V to 12.5V, the resistance value of the first resistor is 8.5kΩ to 9kΩ, and the stable voltage value of the voltage stabilizing tube ranges from 11.7V to 12.3V.
Specifically, in a specific embodiment, when the input voltage of the input end is in the range of 11.5V-12.5V, the first transistor is a P-type field effect transistor with a conducting voltage of 1.3V, at normal temperature of 25 ℃, the voltage at two ends of the negative temperature coefficient thermistor exceeds the conducting voltage of the first transistor, so that the first transistor is fully conducted, the preset protection temperature is set to 60 ℃, when the circuit temperature exceeds the preset protection temperature, the voltage between the source and the grid of the first transistor is lower than the conducting voltage, the first transistor is in an off state, and the input end and the output end are disconnected, so that protection is realized, therefore, when the circuit temperature exceeds the preset protection temperature, the voltage at two ends of the negative temperature coefficient thermistor is lower than the conducting voltage of the first transistor, and at the same time, the resistance of the negative temperature coefficient thermistor is reduced to 1.244kΩ, and then the resistance range of the first resistor is ((11.5-1.3) ×1.244K)/1.3=11.7kΩ, and ((12.5-1.3) ×1.244=1.3 kΩ; the voltage stabilizing tube is selected according to the input voltage of the input end, and in order to ensure the voltage stabilizing effect, the voltage stabilizing value of the voltage stabilizing tube can be 1V-2V higher than the input voltage of the input end, and the voltage stabilizing value range of the selected voltage stabilizer is 11.7-12.3V. In the embodiment of the present utility model, the specific model of each device is not particularly limited.
Optionally, when the voltage value of the output end ranges from 23.5V to 24.5V, the resistance value of the first resistor ranges from 18kΩ to 19kΩ, and the stable voltage value of the voltage stabilizing tube ranges from 23.7V to 24.3V.
Specifically, in a specific embodiment, when the input voltage of the input end is 23.5V-24.5V, the first transistor is a P-type field effect transistor with a conducting voltage of 1.3V, at normal temperature of 25 ℃, the voltage across the negative temperature coefficient thermistor exceeds the conducting voltage of the first transistor, so that the first transistor is fully conducted, the preset protection temperature is set to 60 ℃, when the circuit temperature exceeds the preset protection temperature, the source-gate voltage of the first transistor is lower than the conducting voltage, the first transistor is in an off state, and the input end and the output end are disconnected, so that protection is achieved, therefore, when the circuit temperature exceeds the preset protection temperature, the voltage across the negative temperature coefficient thermistor is lower than the conducting voltage of the first transistor, and at the same time, the resistance of the negative temperature coefficient thermistor is reduced to 1.244kΩ, and then the resistance range of the first resistor is ((23.5-1.3) ×1.244K)/1.3=18kΩ, and ((24.5-1.3) ×1.244=1kΩ)/1.3=19; the voltage stabilizing tube is selected according to the input voltage of the input end, and in order to ensure the voltage stabilizing effect, the voltage stabilizing value of the voltage stabilizing tube can be 1V-2V higher than the input voltage of the input end, and the voltage stabilizing value range of the selected voltage stabilizer is 23.7-24.3V. In the embodiment of the present utility model, the specific model of each device is not particularly limited.
Optionally, when the voltage value of the output end ranges from 27.5V to 28.5V, the resistance value of the first resistor ranges from 21kΩ to 22kΩ, and the stable voltage value of the voltage stabilizing tube ranges from 27.7V to 28.3V.
Specifically, in a specific embodiment, when the input voltage of the input end is in the range of 27.5V-28.5V, the first transistor is a P-type field effect transistor with a conducting voltage of 1.3V, at normal temperature of 25 ℃, the voltage at two ends of the negative temperature coefficient thermistor exceeds the conducting voltage of the first transistor, so that the first transistor is fully conducted, the preset protection temperature is set to 60 ℃, when the circuit temperature exceeds the preset protection temperature, the source-gate voltage of the first transistor is lower than the conducting voltage, the first transistor is in an off state, and the input end and the output end are disconnected, so that protection is realized, therefore, when the circuit temperature exceeds the preset protection temperature, the voltage at two ends of the negative temperature coefficient thermistor is lower than the conducting voltage of the first transistor, and at the same time, the resistance value of the negative temperature coefficient thermistor is reduced to 1.244kΩ, and the resistance value range of the first resistor is ((27.5-1.3) ×1.244K)/1.3=21kΩ, and ((28.5-1.3) ×1.244=12Ω). The voltage stabilizing tube is selected according to the input voltage of the input end, the voltage stabilizing value range of the selected voltage stabilizer is 27.7-28.3V, and in order to ensure the voltage stabilizing effect, the voltage stabilizing value of the voltage stabilizing tube can be 1V-2V higher than the input voltage of the input end. In the embodiment of the present utility model, the specific model of each device is not particularly limited.
In a specific embodiment, as shown in fig. 2, the input voltage of the input end is 5V, a first transistor in the circuit is a P-type field effect transistor, a second transistor is a triode, a zener voltage regulator with a voltage regulator value of 5.6V is selected as the voltage regulator, and a resistance value of the first resistor is 3.5kΩ; at normal temperature of 25 ℃, the resistance value of the negative temperature coefficient thermistor is 5KΩ, the voltage at the two ends of the negative temperature coefficient thermistor is about 2.95V, the voltage between the source and the grid electrode of the P-type field effect transistor is larger than 1.3V of the conducting voltage, the source and the drain of the P-type field effect transistor are conducted, and the input voltage of the input end is output to a load connected with the output end; when the ambient temperature rises to above the preset protection temperature of 60 ℃, for example, when the ambient temperature is 66 ℃, the resistance of the negative temperature coefficient thermistor is reduced to below 1.244KΩ and is 1KΩ, and the voltage at the two ends of the negative temperature coefficient thermistor is 1.1V, namely, the voltage between the source and the grid of the P-type field effect transistor is smaller than 1.3V of the conducting voltage, the source and the drain of the P-type field effect transistor are cut off, and the input voltage at the input end stops outputting to the load at the output end, so that over-temperature protection is realized; and the negative temperature coefficient thermistor is recovered to normal resistance until the ambient temperature is recovered to normal temperature and maintained for a long time, the source-gate voltage of the P-type field effect transistor is larger than the conducting voltage, the source-drain electrode of the P-type field effect transistor is conducted, and the input voltage is output to a load.
When the input voltage is 5V, the input voltage of the base electrode of the triode is smaller than the conduction voltage of the triode due to the voltage division of the second resistor and the third resistor, so that the triode is in a cut-off state during normal operation, the source-gate voltage of the P-type field effect tube is larger than the conduction voltage, and the source-drain electrode of the P-type field effect tube is conducted; when the input voltage is high, if the input voltage is 10V, the input voltage is 5.6V higher than the voltage stabilizing value of the voltage stabilizing tube, the voltage stabilizing tube is reversely broken down, the voltage stabilizing tube generates larger reverse current, meanwhile, the voltage at two ends is kept to be 5.6V of the voltage stabilizing value, the reverse circuit inputs the base electrode of the triode, so that the voltage between the emitter and the base electrode of the triode is increased until the voltage exceeds the conducting voltage of the triode, the collector and the emitter of the triode are conducted, the source electrode and the grid electrode of the P-type field effect tube are in short circuit, the voltage between the source electrode and the grid electrode is changed into 0 and is smaller than the conducting voltage of the P-type field effect tube, the source electrode and the drain electrode of the P-type field effect tube are cut off, and the input voltage stops outputting the load at the output end, so that an overvoltage protection effect is achieved.
The embodiment of the utility model has the following beneficial effects: the embodiment of the utility model comprises a voltage stabilizing tube, a negative temperature coefficient thermistor, an input end, an output end, a first resistor, a first transistor and a second transistor, wherein the transistor comprises a triode or a field effect tube; a first electrode of the first transistor is connected with the input end, and a third electrode of the first transistor is connected with the output end; the negative electrode of the voltage stabilizing tube is connected with the input end, and the positive electrode of the voltage stabilizing tube is grounded; the first end of the negative temperature coefficient thermistor is connected with the first electrode of the first transistor, and the second end of the negative temperature coefficient thermistor is connected with the second electrode of the first transistor; the first electrode of the second transistor is connected with the input end, the second electrode of the second transistor is connected with the negative electrode of the voltage stabilizing transistor, and the third electrode of the second transistor is connected with the second end of the negative temperature coefficient thermistor; one end of the first resistor is connected with the second end of the negative temperature coefficient thermistor, and the other end of the first resistor is grounded; the over-temperature and over-pressure protection is realized by adopting a hardware element, the control and the processing are not performed by adopting software, the realization cost is low, and the processing time delay is reduced; meanwhile, the structure is simple, and parameters can be adjusted by replacing devices.
While the preferred embodiment of the present utility model has been described in detail, the utility model is not limited to the embodiment, and various equivalent modifications and substitutions can be made by those skilled in the art without departing from the spirit of the utility model, and these modifications and substitutions are intended to be included in the scope of the present utility model as defined in the appended claims.
Claims (10)
1. The over-temperature and over-voltage protection circuit is characterized by comprising a voltage stabilizing tube, a negative temperature coefficient thermistor, an input end, an output end, a first resistor, a first transistor and a second transistor, wherein the transistors comprise triodes or field effect transistors;
a first electrode of the first transistor is connected with the input end, and a third electrode of the first transistor is connected with the output end;
the negative electrode of the voltage stabilizing tube is connected with the input end, and the positive electrode of the voltage stabilizing tube is grounded;
the first end of the negative temperature coefficient thermistor is connected with the first electrode of the first transistor, and the second end of the negative temperature coefficient thermistor is connected with the second electrode of the first transistor;
the first electrode of the second transistor is connected with the input end, the second electrode of the second transistor is connected with the negative electrode of the voltage stabilizing tube, and the third electrode of the second transistor is connected with the second end of the negative temperature coefficient thermistor;
one end of the first resistor is connected with the second end of the negative temperature coefficient thermistor, and the other end of the first resistor is grounded.
2. The over-temperature and over-voltage protection circuit according to claim 1, further comprising a second resistor, wherein one end of the second resistor is connected with the input end, and the other end of the second resistor is connected with the negative electrode of the voltage stabilizing tube.
3. The over-temperature and over-voltage protection circuit according to claim 2, further comprising a third resistor, wherein one end of the third resistor is connected to the negative electrode of the regulator tube, and the other end of the third resistor is connected to the second electrode of the second transistor.
4. The over-temperature and over-voltage protection circuit according to claim 1, further comprising a capacitor, one end of the capacitor being connected to the input terminal, the other end of the capacitor being connected to a third electrode of the second transistor.
5. The over-temperature and over-voltage protection circuit according to claim 1, wherein when the output voltage of the output terminal ranges from 2.8V to 3.8V, the resistance of the first resistor ranges from 1.3kΩ to 1.7kΩ, and the stable voltage of the voltage stabilizing tube ranges from 3.1V to 3.5V.
6. The over-temperature and over-voltage protection circuit according to claim 1, wherein when the output voltage of the output terminal ranges from 4.5V to 5.5V, the resistance of the first resistor ranges from 2.9kΩ to 3.3kΩ, and the stable voltage of the voltage stabilizing tube ranges from 5.4V to 5.8V.
7. The over-temperature and over-voltage protection circuit according to claim 1, wherein when the output voltage of the output terminal ranges from 9.5V to 10.5V, the resistance of the first resistor ranges from 6.5kΩ to 7.5kΩ, and the stable voltage of the voltage stabilizing tube ranges from 9.8V to 10.2V.
8. The over-temperature and over-voltage protection circuit according to claim 1, wherein when the output voltage of the output terminal ranges from 11.5V to 12.5V, the resistance of the first resistor ranges from 8.5kΩ to 9kΩ, and the stable value of the voltage stabilizing tube ranges from 11.7V to 12.3V.
9. The over-temperature and over-voltage protection circuit according to claim 1, wherein when the output voltage of the output terminal ranges from 23.5V to 24.5V, the resistance of the first resistor ranges from 18kΩ to 19kΩ, and the stable value of the voltage stabilizing tube ranges from 23.7V to 24.3V.
10. The over-temperature and over-voltage protection circuit according to claim 1, wherein when the output voltage of the output terminal ranges from 27.5V to 28.5V, the resistance of the first resistor ranges from 21kΩ to 22kΩ, and the stable value of the voltage stabilizing tube ranges from 27.7V to 28.3V.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321684238.1U CN220209957U (en) | 2023-06-28 | 2023-06-28 | Over-temperature and over-voltage protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321684238.1U CN220209957U (en) | 2023-06-28 | 2023-06-28 | Over-temperature and over-voltage protection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN220209957U true CN220209957U (en) | 2023-12-19 |
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|---|---|---|---|
| CN202321684238.1U Active CN220209957U (en) | 2023-06-28 | 2023-06-28 | Over-temperature and over-voltage protection circuit |
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| Country | Link |
|---|---|
| CN (1) | CN220209957U (en) |
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2023
- 2023-06-28 CN CN202321684238.1U patent/CN220209957U/en active Active
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