A high voltage constant voltage circuit based on operational amplifier
By designing a high-voltage constant voltage circuit based on an op amp, including a constant voltage unit circuit and an overcurrent protection unit circuit, the existing high-voltage constant voltage power supply circuit is solved, and the high-voltage constant voltage function with a simple circuit structure and low cost is realized, and the overcurrent protection function is equipped.
Patent Information
- Application Number
- CN202421434818.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-21
- Publication Date
- 2025-04-11
- Estimated Expiration
- 2034-06-21
AI Technical Summary
The existing high-voltage constant voltage power supply circuits are complex and large in size, making it difficult to achieve a simple circuit structure and low cost design.
A high-voltage constant voltage circuit based on an op amp is designed, including a constant voltage unit circuit and an overcurrent protection unit circuit. Constant voltage regulation is realized through error amplification circuit, output voltage division circuit and RC absorption circuit, and overcurrent protection is realized through overcurrent detection circuit, comparator and transistor.
It realizes the high-voltage constant voltage function with a simple circuit structure and low cost, and has an overcurrent protection function to ensure the stable output voltage and effectively prevent overcurrent.
Smart Images
Figure CN222748902U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of electronic circuits, in particular to a high-voltage constant-voltage circuit based on an operational amplifier. Background Art
[0002] In the power supply circuits of many electronic devices, high-voltage constant-voltage power supply is required. Some high-voltage constant-voltage power supplies use switching power supplies, and switching power supplies use magnetic core transformers, which make the circuits complex and large in size. Utility Model Content
[0003] In view of this, it is necessary to provide a high-voltage constant-voltage circuit based on an operational amplifier with a simple circuit structure and low cost.
[0004] A high-voltage constant voltage circuit based on an operational amplifier comprises a constant voltage unit circuit and an overcurrent protection unit circuit, wherein the constant voltage unit circuit comprises an error amplifier circuit, an output voltage divider circuit, and an RC absorption circuit, wherein the output voltage divider circuit is connected to the output end of a voltage-stabilized power supply, and the output end of the output voltage divider circuit is connected to the input end of the error amplifier circuit, wherein the error amplifier circuit amplifies the error signal output by the output voltage divider circuit to realize the constant voltage unit circuit regulating the output voltage of the voltage-stabilized power supply, wherein the output end of the overcurrent protection unit circuit is connected to the control end of the constant voltage unit circuit, wherein the overcurrent protection unit circuit comprises an overcurrent detection circuit, a comparator, and a triode, wherein the overcurrent The detection circuit detects the output current of the voltage-stabilized power supply, the output end of the overcurrent detection circuit is connected to the input end of the comparator, the output end of the comparator is connected to the base of the transistor, the overcurrent protection unit circuit detects the output current of the voltage-stabilized power supply through the overcurrent detection circuit, the output of the overcurrent detection circuit is compared with the overcurrent reference threshold value through the comparator, and when the output current of the voltage-stabilized power supply exceeds the threshold value, the output voltage is shut off by the transistor to realize the protection function, and the RC absorption circuit includes a resistor and capacitor series circuit, one end of the RC absorption circuit is connected to the output end of the voltage-stabilized power supply, and the other end of the RC absorption circuit is connected to the output end of the output voltage divider circuit.
[0005] Furthermore, the constant voltage unit circuit includes a voltage stabilizing source U10, a ninth voltage stabilizing tube Z9, a tenth voltage stabilizing tube Z10, a sixth eighth diode D68, a sliding resistor VR1, a resistor R88, a resistor R44, a resistor R9, a resistor R25, a resistor R29, a resistor R8, a capacitor C77, a capacitor C10, a capacitor C16, and a resistor R132. The voltage stabilizing source U10 is the error amplifier circuit, and the reference pole of the voltage stabilizing source U10 is the input end of the error amplifier circuit. The sliding resistor VR1, the resistor R88, and the resistor R44 are connected in series to form an output voltage divider circuit. The series connection point of the resistor R88 and the resistor R44 is the output end of the output voltage divider circuit. The resistor R 9 is connected in parallel to the output end of the output voltage divider circuit, the output end of the output voltage divider circuit is connected to the reference electrode of the voltage stabilizing source U10, the first end of the resistor R8, and the first end of the capacitor C80, the second end of the resistor R8 is connected to the first end of the capacitor C77, the first end of the capacitor C77 is connected to the second end of the capacitor C80, the negative electrode of the voltage stabilizing source U10, and the positive electrode of the tenth voltage stabilizing tube Z10, the negative electrode of the sixth eight diode D68 is connected to the negative electrode of the ninth voltage stabilizing tube Z9, the positive electrode of the ninth voltage stabilizing tube Z9 is connected to the negative electrode of the tenth voltage stabilizing tube Z10, the positive electrode of the sixth eight diode D68 is connected to the +57V power supply through the resistor R25, the resistor R25 is the current limiting resistor of the voltage stabilizing source U10, and provides a suitable working point for the error amplifier.
[0006] Furthermore, after resistor R8 is connected in series with capacitor C77, it is connected in parallel with capacitor C80 as a resistor-capacitor loop filter, connected in parallel between the negative electrode and the reference electrode of the voltage regulator U10, and connected to the output end of the output voltage divider circuit to eliminate disturbances at the output end of the output voltage divider circuit.
[0007] Furthermore, the RC absorption circuit includes a capacitor C10, a capacitor C16, and a resistor R132 connected in series. The function of the RC absorption circuit is to smooth the peak voltage on the output end of the voltage-stabilized power supply. The peak voltage superimposed on the output end of the voltage-stabilized power supply will cause the output voltage of the output end of the voltage-stabilized power supply to fluctuate unstably. The RC absorption circuit is connected to absorb the peak voltage during startup, so that the output voltage of the output end of the voltage-stabilized power supply can rise smoothly when the power is turned on. The capacitors C10 and C16 are preferably 0.1UF, and the resistor R132 is preferably 11k.
[0008] Furthermore, the overcurrent protection circuit includes an operational amplifier U5-A, an operational amplifier U5-B, a fourth voltage regulator U4, a transistor Q3, a diode D67, an optocoupler diode OT1-B, a sampling resistor R67, a resistor R65, a capacitor C48, a capacitor C32, a capacitor C31, a resistor R26, and a capacitor C42. The sampling resistor R67, the capacitor C31, the capacitor C48, the resistor R26, the capacitor C30, and the operational amplifier U5-A form the differential amplifier. The capacitor C31 is connected in parallel with the negative input and output of the operational amplifier U5-A, and the resistor R26 is connected in parallel with the negative input of the operational amplifier U5-A. The output terminal is connected in parallel with the output terminal, C30 is connected in parallel between the positive input terminal and the negative input terminal of the operational amplifier U5-A, and serves as an input filter capacitor of the differential amplifier to filter out startup interference noise. The overcurrent detection signal is amplified by the differential amplifier and output from the output terminal, and then connected to the positive input terminal of the comparator and the first terminal of the capacitor C42 through the resistor R77. The second terminal of the capacitor C42 is grounded. The capacitor C42 filters the overcurrent detection signal input to the comparator. The comparator includes a resistor R65, a capacitor C32, an operational amplifier U5-B, a capacitor C42, and a reference power supply. The resistor R65 and the capacitor C32 are connected in series and then in parallel. Between the output pin 7 and the negative input terminal of the operational amplifier U5-B, the output control signal of the comparator is sent to a comparison voltage divider composed of resistors R75 and R79 connected in series. The output of the comparison voltage divider is connected to the base of the transistor Q3. The capacitor C44 and the resistor R79 are connected in parallel as the input filter capacitor of the base of the transistor Q3 to filter out the peak interference and clutter of the output control signal of the comparison voltage divider. The emitter of the transistor Q3 is grounded, and the collector of the transistor Q3 is connected to the cathode of the diode D67. The anode of the diode D67 is connected to the cathode of the optocoupler diode OT1-B and the first pin of the resistor R25. The optocoupler 2 The positive electrode of the optocoupler diode OT1-B is connected to the second pin of the resistor R25 and connected to the +57V power supply through the resistor R29. The resistor R29 is the bias resistor of the optocoupler diode OT1-B, and fine-tunes the current flowing through the optocoupler diode OT1-B. The on and off of the transistor Q3 can effectively control the output overcurrent protection. The reference power supply includes a resistor R63, a fourth voltage regulator U4, and a capacitor C43. The first end of the resistor R63 is connected to the VDD power supply, the first end of the resistor R63 is connected to the negative electrode and the reference electrode of the fourth voltage regulator U4, the positive electrode of the fourth voltage regulator U4 is grounded, and the capacitor C43 is connected in parallel with the fourth voltage regulator U4.
[0009] Furthermore, an output voltage divider circuit composed of a sliding resistor VR1, a resistor R88, and a resistor R44 connected in series detects changes in the output voltage. The output voltage divider circuit divides the output error voltage to the reference electrode of the voltage stabilizing source U10, so that the voltage between the positive and negative electrodes of the voltage stabilizing source U10 changes, thereby adjusting the current flowing through the optocoupler diode OT1-B, and feeding back to the control chip of the voltage stabilizing power supply through the optocoupler transistor OT1-B to adjust the output voltage to keep the output voltage stable. The optocoupler diode OT1-B is connected in series with a resistor R29, which is a bias resistor of the optocoupler diode OT1-B and fine-tunes the current flowing through the optocoupler diode OT1-B. The resistor R65 and the capacitor C32 are connected in series and then connected in parallel between the output pin 7 and the negative input terminal of the operational amplifier U5-B.
[0010] Furthermore, the overcurrent protection circuit also includes a comparator, which is composed of an op amp U5-B, a capacitor C32, a resistor R65, a resistor R78, and a fourth voltage regulator U4. The fourth voltage regulator U4 serves as a reference power supply for the comparator, and the resistor R63 is a current limiting resistor of the fourth voltage regulator U4. The capacitor C43 is connected in parallel with the fourth voltage regulator U4 as a filter for the fourth voltage regulator U4. The fourth voltage regulator U4 serves as a reference power supply for the comparator and is connected to the negative input terminal of the op amp U5-B through the resistor R78. The voltage across the sampling resistor R67 is connected to the positive and negative input terminals of the op amp U5-A through the resistor R59 and the resistor R60. After being amplified by the op amp U5-A, it is connected to the input terminal of the comparator and the positive input terminal of the op amp U5-B through the resistor R77. The output terminal of the op amp U5-B is connected to the second end of the resistor R75.
[0011] Working parameters: The resistance values of the resistors R60, R59, R77 and R78 of the resistor arm are all 1KΩ, the resistance value of the amplifying resistor R26 is 82kΩ, the resistance value of the sampling resistor R67 is 5mΩ, the voltage-dividing resistors R75 and R79 are both 3kΩ, the base of the transistor Q3 is connected to the first end of the resistor R75, the resistor R79 and the capacitor C44, the second ends of the resistor R79 and the capacitor C44 are grounded, the capacitance of the capacitor C44 is 0.1UF, and the function of the capacitor is to filter to prevent the peak voltage from turning on the transistor Q3, the capacitance of the capacitor C31 is 0.33uF, and the capacitance of the capacitor C30 is 0.1UF, which is used to prevent the interference signal generated when the power is turned on, the resistor R65 and the capacitor C32 are the loop of the LM2904 comparator, the resistance value of the resistor R65 is 0Ω, the capacitance value of the capacitor C32 is 1UF, and the capacitance value of the capacitor C48 is 0.47UF.
[0012] The above-mentioned high-voltage constant-voltage circuit based on operational amplifier uses the voltage-stabilizing characteristics of the ninth voltage-stabilizing tube Z9 and the tenth voltage-stabilizing tube Z10 for voltage clamping by setting a constant-voltage unit circuit and an overcurrent protection unit circuit. The circuit is simple and has low power consumption, and realizes the constant-voltage function of the output high voltage. The voltage of the output high voltage can be controlled by adjusting the adjustable resistor, thereby realizing the overcurrent protection function of the output high-voltage constant-voltage circuit. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 It is a schematic diagram of a high voltage constant voltage circuit based on an operational amplifier according to an embodiment of the utility model. DETAILED DESCRIPTION
[0014] The present invention will be described in detail below with reference to specific embodiments and accompanying drawings.
[0015] See also Figure 1 , showing a high-voltage constant voltage circuit based on an operational amplifier provided by an embodiment of the utility model, including a constant voltage unit circuit and an overcurrent protection unit circuit. The constant voltage unit circuit adjusts and controls the output voltage of the voltage-stabilized power supply. The output end of the overcurrent protection unit circuit is connected to the control end of the constant voltage unit circuit. The overcurrent protection unit circuit detects the output current size and shuts off the output voltage when the output current exceeds the threshold to achieve a protection function.
[0016] Furthermore, the constant voltage unit circuit includes a voltage stabilizing source U10, a ninth voltage stabilizing tube Z9, a tenth voltage stabilizing tube Z10, a sixth eighth diode D68, a sliding resistor VR1, a resistor R88, a resistor R44, a resistor R9, a resistor R25, a resistor R29, a resistor R8, a capacitor C77, a capacitor C10, a capacitor C16, and a resistor R132. The sliding resistor VR1, the resistor R88, and the resistor R44 are connected in series to form an output voltage divider circuit. The series connection point of the resistor R88 and the resistor R44 is the output end of the output voltage divider circuit. The resistor R9 is connected in parallel to the output end of the output voltage divider circuit. The output voltage divider circuit The output end is connected to the reference electrode of the voltage-stabilizing source U10, the first end of the resistor R8, and the first end of the capacitor C80. The second end of the resistor R8 is connected to the first end of the capacitor C77. The first end of the capacitor C77 is connected to the second end of the capacitor C80, the negative electrode of the voltage-stabilizing source U10, and the positive electrode of the tenth voltage-stabilizing tube Z10. The negative electrode of the sixth-eighth diode D68 is connected to the negative electrode of the ninth voltage-stabilizing tube Z9, and the positive electrode of the ninth voltage-stabilizing tube Z9 is connected to the negative electrode of the tenth voltage-stabilizing source Z10. The positive electrode of the sixth-eighth diode D68 is connected to the +57V power supply through the resistor R25. The resistor R25 is the current-limiting resistor of the voltage-stabilizing source U10, and provides a suitable operating point for the error amplifier.
[0017] Furthermore, after resistor R8 is connected in series with capacitor C77, it is connected in parallel with capacitor C80 as a resistor-capacitor loop filter, and is connected in parallel between the negative electrode and the reference electrode of the voltage regulator U10, and is also connected to the output end of the output voltage divider circuit to eliminate disturbances at the output end of the output voltage divider circuit. The model of the voltage regulator U10 is AZ431AN.
[0018] Furthermore, capacitor C10, capacitor C16, and resistor R132 are connected in series to form an RC absorption circuit. Capacitor C10 and capacitor C16 are 0.1UF, and resistor R132 is 11k. The function of the RC absorption circuit is to smooth the output voltage overshoot voltage, which causes abnormal fluctuations in the output voltage. The RC absorption circuit is connected to absorb the peak voltage during startup to make the output voltage rise smoothly.
[0019] The adjustable resistance range of the sliding resistor VR1 is 0-10K, the resistor R88 is 39K, the resistor R44 is 2.2K, when the sliding resistor VR1 is 0Ω, the output voltage Vout is 46V; when the sliding resistor VR1 is 10k, the output voltage Vout is 57V. The function of this loop is to control the output voltage Vout by adjusting the resistance of the sliding resistor VR1, and the adjustable range is 46V-57V. The resistor R25 is 1.8K, which is a voltage divider resistor to control the voltage through the optocoupler. The resistor R29 is the bias resistor of the optocoupler OT1-B, and the selected resistance value is 4.7KΩ. The current flowing through the optocoupler OT1-B can be fine-tuned through this resistor R29. The resistor R8, capacitor C77, and capacitor C80 are loop resistors and capacitors, which are used to adjust the speed of change of the voltage loop of the voltage regulator U10. The resistance value of resistor R8 is 1K, the capacitance value of capacitor C77 is 1UF, and the capacitance value of capacitor C80 is 220pF.
[0020] Furthermore, the overcurrent protection circuit includes an op amp U5A, an op amp U5B, a voltage regulator U4, a transistor Q3, a diode D67, an optocoupler diode OT1-B, a sampling resistor R67, a resistor R65, a capacitor C32, a capacitor C31, a capacitor C30, a resistor R26, a resistor R29, a resistor R25, a sampling resistor R67, a capacitor C31, a resistor R26, a capacitor C30, and an op amp U5-A to form a differential amplifier, the capacitor C31 is connected in parallel with the negative input and output of the op amp U5-A, the resistor R26 is connected in parallel with the negative input of the op amp U5-A, and the resistor R26 is connected in parallel with the negative input of the op amp U5-A. The output terminal is connected in parallel with the output terminal, and the capacitor C30 is connected in parallel between the input positive and negative terminals of the operational amplifier U5-A, as an input filter capacitor of the differential amplifier to filter out the interference noise when starting up. The overcurrent detection signal is amplified by the differential amplifier and output from the output terminal, and then connected to the positive input terminal of the comparator and the first terminal of the capacitor C42 through the resistor R77. The second terminal of the capacitor C42 is grounded. The capacitor C42 filters the overcurrent detection signal input to the comparator. The comparator includes a resistor R65, a capacitor C32, an operational amplifier U5-B, and a reference power supply. The resistor R65 and the capacitor C32 are connected in series and then connected in parallel. Between the output pin 7 and the negative input terminal of the operational amplifier U5-B, the output control signal of the comparator is sent to a comparison voltage divider composed of resistors R75 and R79 connected in series. The output of the comparison voltage divider is connected to the base of the transistor Q3. The capacitor C44 and the resistor R79 are connected in parallel as the input filter capacitor of the base of the transistor Q3 to filter out the spike interference clutter of the output control signal of the voltage divider. The emitter of the transistor Q3 is grounded, and the collector of the transistor Q3 is connected to the cathode of the diode D67. The anode of the diode D67 is connected to the cathode of the optocoupler diode OT1-B and the first pin of the resistor R25. The positive electrode of the optocoupler diode OT1-B is connected to the second pin of the resistor R25 and connected to the +57V power supply through the resistor R29. The resistor R29 is the bias resistor of the optocoupler diode OT1-B, and fine-tunes the current flowing through the optocoupler diode OT1-B. The on and off of the transistor Q3 can effectively control the output overcurrent protection. The reference power supply includes a resistor R63, a Zener diode U4, and a capacitor C43. The first end of the resistor R63 is connected to the VDD power supply, the first end of the resistor R63 is connected to the negative electrode and the reference electrode of the Zener diode U4, the positive electrode of the Zener diode U4 is grounded, and the capacitor C43 is connected in parallel with the Zener diode U4.
[0021] This circuit also has an output overcurrent function, and uses the op amp U5-A to achieve the overcurrent protection function. Its working principle is to sample the voltage across the resistor R67, and after differential amplification by the op amp U5-A, use the reference voltage 2.5V of the voltage regulator U4 as a reference, and short-circuit the 1st and 3rd pins of the voltage regulator U4 to obtain a stable voltage of 2.5V. The voltage after differential amplification by the op amp U5-A and the reference voltage are compared after being compared by the op amp U5-B. Since the transistor Q3 is an NPN transistor, its characteristic is that the transistor is turned on when the base input is high, and it is cut off when the base input is low. The overcurrent point of the output current can be controlled by controlling the conduction and shutdown of the transistor Q3, and the diode D67 controls the current direction. When the overcurrent signal detected by the sampling resistor R67 is less than the reference voltage 2.5V after differential amplification by the operational amplifier U5-A, the operational amplifier U5-B compares the overcurrent signal voltage with the reference voltage, and the 7th pin of the operational amplifier U5-B outputs a low level. The base of the transistor Q3 is cut off and does not conduct due to the input low level, the collector of the transistor Q3 is high, the diode D67 is cut off, and the current flows through the diode D68 to the direction of the voltage regulator Z9, the voltage regulator Z10, and the voltage regulator U10, without triggering the current overcurrent point; when the sampling resistor R67 detects When the voltage of the overcurrent signal after differential amplification by the operational amplifier U5-A is greater than the reference voltage of 2.5V, the operational amplifier U5-B compares the overcurrent signal voltage with the reference voltage, and the 7th pin of the operational amplifier U5-B outputs a high level. The base of the transistor Q3 is turned on due to the input high level, and the collector of the transistor Q3 is grounded through the emitter of the transistor Q3. The current of the diode D67 will flow through the collector of the transistor Q3 to the emitter of the transistor Q3 to the ground. The voltage regulator U10 cannot work normally because no current flows through it. At this time, the current overcurrent point is triggered, and the output voltage Vout, that is, the 57V output voltage is restarted until the operational amplifier U5-A stops working.
[0022] Specifically, the models of the operational amplifiers U5-A and U5-B are LM2904. Since the maximum rated voltage of the LM2904 power supply voltage VDD is 36V, the power supply voltage for LM2904 must be lower than 36V. As a result, when the voltage of the overcurrent signal detected by the sampling resistor R67 after differential amplification is greater than the reference voltage 2.5V, after comparison, the operational amplifier U5-B outputs a high level at pin 7 of the operational amplifier U5-B. At this time, the high level voltage is 36V, and then the transistor Q3 is equivalent to a control switch, and the high level output of pin 7 of the operational amplifier U5-B is divided and output to the base of the transistor Q3 through the voltage divider resistors R75 and R79, which provides a driving voltage and current for the opening of the transistor Q3.
[0023] In this embodiment, its main function is to achieve constant voltage and output overcurrent protection when outputting high voltage. Figure 1The right side is the output constant voltage circuit. When it works normally, the reference 2.5V voltage of the voltage regulator U10 is used as the reference standard voltage. The voltage across the sliding resistor VR1 is adjusted to control the current flowing through the optocoupler diode OT1-B. The current is fed back to the FB pin of the IC through the optocoupler transistor OT1-A to control the output voltage and achieve stable output of the output voltage. Since the working voltage VKAmax of the voltage regulator U10 is 36V, if the VKA added to the voltage regulator U10 is greater than 36V, the reference 2.5V voltage of the voltage regulator U10 will be in an unstable state, and the reference voltage is prone to oscillation, resulting in excessive output voltage deviation and unstable output voltage.
[0024] In this embodiment, the circuit is applied to an output voltage Vout of 48V-57V, and the voltage regulation value of the Zener diodes Z9 and Z10 is 18V. After the clamping diodes of the two 18V Zener diodes Z9 and Z10 are connected in series to clamp and divide the voltage, the VKA voltage applied to the voltage regulator U10 is less than 36V. When outputting a high voltage, it is ensured that the VKA voltage applied to the voltage regulator U10 can operate within the normal working voltage range, so that the reference voltage 2.5V of the comparator is in a normal state.
[0025] In this embodiment, the resistance values of resistors R60, R59, R77 and R78 are all 1KΩ, the amplifying resistor R26 is 82kΩ, the sampling resistor R67 is 5mΩ, the voltage-dividing resistors R75 and R79 are 3kΩ, the capacitance of capacitor C44 is 0.1UF, which is used to filter the output of the comparator to prevent the peak voltage from turning on the transistor Q3, the capacitance of capacitor C31 is 0.33uF, which filters out the peak interference after sampling and amplification, the capacitor C30 is 0.1UF to prevent the interference signal generated when the power is turned on, the resistor R65 and the capacitor C32 are the loop of the comparator composed of the operational amplifier U5-B, the resistance of resistor R65 is 0Ω, the capacitance of capacitor C32 is 1UF, and the capacitance of capacitor C48 is 0.47UF.
[0026] The above-mentioned high-voltage constant voltage circuit based on operational amplifier can realize the output high-voltage constant voltage function, and can control the output voltage and realize the output over-current protection function by adjusting the adjustable resistor. The on and off of transistor Q3 can effectively control the output over-current protection. The voltage regulator U10 and the voltage regulator U4 are of the model AZ431AN, which effectively provides an accurate 2.5V reference voltage, so that this circuit can control the output voltage more accurately.
[0027] It should be noted that the present invention is not limited to the above-mentioned embodiments. According to the creative spirit of the present invention, those skilled in the art may also make other changes. These changes made according to the creative spirit of the present invention should be included in the scope of protection required by the present invention.
Claims
1. A high voltage constant voltage circuit based on an operational amplifier, characterized in that: The invention comprises a constant voltage unit circuit and an overcurrent protection unit circuit, wherein the constant voltage unit circuit comprises an error amplifier circuit, an output voltage divider circuit, and an RC absorption circuit, wherein the output voltage divider circuit is connected to the output end of the voltage-stabilized power supply, and the output end of the output voltage divider circuit is connected to the input end of the error amplifier circuit, wherein the error amplifier circuit amplifies the error signal output by the output voltage divider circuit so that the constant voltage unit circuit can regulate the output voltage of the voltage-stabilized power supply, wherein the output end of the overcurrent protection unit circuit is connected to the control end of the constant voltage unit circuit, wherein the overcurrent protection unit circuit comprises an overcurrent detection circuit, a comparator, and a triode, wherein the overcurrent detection circuit detects The output current of the voltage-stabilized power supply is measured, the output end of the overcurrent detection circuit is connected to the input end of the comparator, the output end of the comparator is connected to the base of the transistor, the overcurrent protection unit circuit detects the output current of the voltage-stabilized power supply through the overcurrent detection circuit, the output of the overcurrent detection circuit is compared with the overcurrent reference threshold value through the comparator, and when the output current of the voltage-stabilized power supply exceeds the threshold value, the output voltage is shut off to realize the protection function, the RC absorption circuit includes a resistor and capacitor series circuit, one end of the RC absorption circuit is connected to the output end of the voltage-stabilized power supply, and the other end of the RC absorption circuit is connected to the output end of the output voltage divider circuit.
2. The high voltage constant voltage circuit based on operational amplifier according to claim 1, characterized in that: The constant voltage unit circuit includes a voltage stabilizing source U10, a ninth voltage stabilizing tube Z9, a tenth voltage stabilizing tube Z10, a sixth eighth diode D68, a sliding resistor VR1, a resistor R88, a resistor R44, a resistor R9, a resistor R25, a resistor R29, a capacitor C10, a capacitor C16, and a resistor R132. The voltage stabilizing source U10 is the error amplifier circuit, and the reference pole of the voltage stabilizing source U10 is the input end of the error amplifier circuit. The sliding resistor VR1, the resistor R88, and the resistor R44 are connected in series to form an output voltage divider circuit. The series connection point of the resistor R88 and the resistor R44 is the output end of the output voltage divider circuit. Resistor R9 is connected in parallel to the output end of the output voltage divider circuit, and the output end of the output voltage divider circuit is connected to the reference electrode of the voltage stabilizing source U10, the first end of the resistor R8, and the first end of the capacitor C80. The second end of the resistor R8 is connected to the first end of the capacitor C77, the first end of the capacitor C77 is connected to the second end of the capacitor C80, the negative electrode of the voltage stabilizing source U10, and the positive electrode of the tenth voltage stabilizing tube Z10. The negative electrode of the sixth-eighth diode D68 is connected to the negative electrode of the ninth voltage stabilizing tube Z9, and the positive electrode of the ninth voltage stabilizing tube Z9 is connected to the negative electrode of the tenth voltage stabilizing tube Z10. The positive electrode of the sixth-eighth diode D68 is connected to the +57V power supply through the resistor R25, and the resistor R25 is the current limiting resistor of the voltage stabilizing source U10.
3. The high voltage constant voltage circuit based on operational amplifier according to claim 2, characterized in that: The constant voltage unit circuit also includes a resistor R8, capacitors C77 and C80. The resistor R8 is connected in series with the capacitor C77 and then connected in parallel with the capacitor C80, and is connected in parallel between the negative electrode and the reference electrode of the voltage stabilizing source U10 as a resistor-capacitor loop filter. The connection point of the capacitor C80 and the resistor R8 is simultaneously connected to the reference electrode connected to the voltage stabilizing source U10 and the output end of the output voltage divider circuit to eliminate clutter disturbance at the output end of the output voltage divider circuit.
4. The high voltage constant voltage circuit based on operational amplifier according to claim 2, characterized in that: The constant voltage unit circuit also includes a capacitor C10, a capacitor C16, and a resistor R132. The capacitor C10, the capacitor C16, and the resistor R132 are connected in series to form the RC absorption circuit to absorb the peak voltage on the output end when the voltage-stabilized power supply is turned on.
5. The high voltage constant voltage circuit based on operational amplifier according to claim 2, characterized in that: The overcurrent protection circuit includes an operational amplifier U5-A, an operational amplifier U5-B, a fourth voltage regulator U4, a transistor Q3, a diode D67, an optocoupler diode OT1-B, a sampling resistor R67, a resistor R65, a capacitor C32, a capacitor C31, a resistor R26, a resistor R77, a capacitor C42, and a sampling resistor R67, a capacitor C31, a resistor R26, a capacitor C30, and an operational amplifier U5-A to form a differential amplifier. The capacitor C31 is connected in parallel with the negative input and output ends of the operational amplifier U5-A, and the resistor R26 is connected in parallel with the negative input and output ends of the operational amplifier U5-A. The negative input terminal and the output terminal are connected in parallel, and the capacitor C30 is connected in parallel between the positive input terminal and the negative input terminal of the operational amplifier U5-A, as the input filter capacitor of the differential amplifier to filter out the startup interference clutter. The overcurrent detection signal is amplified by the differential amplifier and output from the output terminal and then connected to the positive input terminal of the comparator and the first end of the capacitor C42 through the resistor R77. The second end of the capacitor C42 is grounded. The capacitor C42 filters the overcurrent detection signal input to the comparator. The comparator includes a resistor R65, a capacitor C32, and an operational amplifier U5-B. , reference power supply, resistor R65 and capacitor C32 are connected in series and then connected in parallel between output pin 7 and negative input terminal of operational amplifier U5-B, the output control signal of the comparator is sent to a comparison voltage divider composed of resistor R75 and resistor R79 connected in series, the output of the comparison voltage divider is connected to the base of transistor Q3, capacitor C44 and resistor R79 are connected in parallel as input filter capacitors of the base of transistor Q3, and the peak interference clutter of the output control signal of the comparison voltage divider is filtered out, the emitter of transistor Q3 is grounded, and the collector of transistor Q3 is connected to diode D The cathode of diode D67 is connected to the cathode of optocoupler diode OT1-B and the first pin of resistor R25. The anode of optocoupler diode OT1-B is connected to the second pin of resistor R25 through resistor R29 and connected to the +57V power supply. Resistor R29 is the bias resistor of optocoupler diode OT1-B, which can fine-tune the current flowing through optocoupler diode OT1-B. The current of diode D67 will flow to the emitter of transistor Q3 to ground through the collector of transistor Q3. The on and off of transistor Q3 is used to control the output overcurrent protection.
6. The high voltage constant voltage circuit based on operational amplifier as claimed in claim 5, characterized in that: The reference power supply includes a resistor R63, a fourth voltage regulator U4, a capacitor C43, and a resistor R78. The first end of the resistor R63 is connected to the VDD power supply, the first end of the resistor R63 is connected to the negative electrode and the reference electrode of the fourth voltage regulator U4, the positive electrode of the fourth voltage regulator U4 is grounded, the capacitor C43 is connected in parallel with the fourth voltage regulator U4, and the regulated output of the fourth voltage regulator U4 is connected to the negative input terminal of the operational amplifier U5-B.