CN117439593B - Clamping circuit, analog optocoupler circuit and isolation driving circuit - Google Patents
Clamping circuit, analog optocoupler circuit and isolation driving circuit Download PDFInfo
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- CN117439593B CN117439593B CN202311763395.6A CN202311763395A CN117439593B CN 117439593 B CN117439593 B CN 117439593B CN 202311763395 A CN202311763395 A CN 202311763395A CN 117439593 B CN117439593 B CN 117439593B
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K19/00—Logic circuits, i.e. having at least two inputs acting on one output; Inverting circuits
- H03K19/003—Modifications for increasing the reliability for protection
- H03K19/00369—Modifications for compensating variations of temperature, supply voltage or other physical parameters
- H03K19/00384—Modifications for compensating variations of temperature, supply voltage or other physical parameters in field effect transistor circuits
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K19/00—Logic circuits, i.e. having at least two inputs acting on one output; Inverting circuits
- H03K19/0175—Coupling arrangements; Interface arrangements
- H03K19/0185—Coupling arrangements; Interface arrangements using field effect transistors only
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Abstract
The invention relates to the technical field of isolation driving chips, and provides a clamping circuit, an analog optocoupler circuit and an isolation driving circuit. The clamp circuit includes: the low-temperature drift circuit receives an input voltage signal through the low-temperature drift circuit and clamps the input voltage signal to obtain an output voltage signal, the low-temperature drift circuit comprises a positive temperature coefficient branch and a negative temperature coefficient branch which are connected in series, and the output voltage signal of the low-temperature drift circuit is the sum of the voltage signals at two ends of the positive temperature coefficient branch and the voltage signals at two ends of the negative temperature coefficient branch; and the overcharge prevention circuit is coupled with the low-temperature drift circuit, receives the output voltage signal of the low-temperature drift circuit, and performs overcharge prevention treatment on the output voltage signal of the low-temperature drift circuit to obtain a clamping voltage signal. The technical effects include that the low temperature drift circuit clamps the voltage between the anode and the cathode, and the overcharge prevention circuit reduces overshoot when the voltage between the anode and the cathode suddenly changes, so as to output a clamping voltage signal stabilized at the voltage value of the optocoupler.
Description
Technical Field
The invention relates to the technical field of isolation driving chips, in particular to a clamping circuit, an analog optocoupler circuit and an isolation driving circuit.
Background
The clamping circuit is a common electronic circuit and has wide application fields, such as signal amplitude limiting, power supply voltage stabilization, temperature compensation, waveform trimming, voltage detection and the like. Clamping circuits are often used to limit an input voltage signal to a fixed voltage range to ensure a stable operating voltage, which is important for precision measurement instruments and computer systems that require high voltage.
In addition, in some occasions where some optocouplers are replaced, the clamping circuit is also important. In the related art, the optical coupler is adopted for signal transmission, so that the problems of light attenuation, slow transmission rate, high error rate and the like exist. Therefore, there is a need to design an alternative optocoupler, and the core idea of the alternative optocoupler is to form the optocoupler voltage, i.e. to stabilize the output voltage at the forward turn-on voltage from the anode to the cathode of the light emitting diode in the optocoupler circuit.
Disclosure of Invention
The invention aims to provide a clamping circuit, an analog optocoupler circuit and an isolation driving circuit, which are used for solving the problems in the related art.
To achieve the above object, according to a first aspect of the embodiments of the present invention, there is provided a clamp circuit including: the low-temperature drift circuit is provided with a positive input end and a negative input end, receives an input voltage signal through the positive input end and the negative input end of the low-temperature drift circuit, clamps the input voltage signal to obtain an output voltage signal of the low-temperature drift circuit, and comprises a positive temperature coefficient branch and a negative temperature coefficient branch which are connected in series, wherein the output voltage signal of the low-temperature drift circuit is the sum of the voltage signals at two ends of the positive temperature coefficient branch and the voltage signals at two ends of the negative temperature coefficient branch; and the overcharge prevention circuit is coupled with the low-temperature drift circuit, receives the output voltage signal of the low-temperature drift circuit, and performs overcharge prevention treatment on the output voltage signal of the low-temperature drift circuit to obtain a clamping voltage signal.
According to a second aspect of an embodiment of the present invention, there is provided an analog optocoupler circuit including: the clamp circuit of any one of the first aspects, wherein the input voltage signal is a pulse width modulation signal; and the isolation conversion circuit is coupled with the clamping circuit and is used for electrically isolating the clamping voltage signal output by the clamping circuit and outputting a control signal, and the control signal characterizes the clamping voltage signal.
According to a third aspect of an embodiment of the present invention, there is provided an isolation driving circuit including: the clamp circuit of any one of the first aspects, wherein the input voltage signal is a pulse width modulation signal; the isolation conversion circuit is coupled with the clamping circuit and is used for electrically isolating the clamping voltage signal output by the clamping circuit and outputting a control signal, and the control signal characterizes the clamping voltage signal; the driving circuit is coupled with the isolation conversion circuit and is used for receiving the control signal and generating a driving signal according to the control signal so as to drive the power switch to be turned on and turned off.
The beneficial effects of the invention are as follows:
through the technical scheme, the clamping circuit comprises the low-temperature drift circuit and the overcharge prevention circuit, the positive input end and the negative input end of the low-temperature drift circuit are used for receiving input voltage signals, clamping processing is carried out on the input voltage signals to obtain output voltage signals of the low-temperature drift circuit, the overcharge prevention circuit is used for receiving the output voltage signals of the low-temperature drift circuit, and the overcharge prevention processing is carried out on the output voltage signals of the low-temperature drift circuit to obtain the clamping voltage signals. The low-temperature drift circuit clamps the voltage between the anode and the cathode, and the overcharge prevention circuit reduces overshoot when the voltage between the anode and the cathode suddenly changes, so that a clamping voltage signal stabilized at an optocoupler voltage value is output.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate the invention and together with the description serve to explain, without limitation, the invention. In the drawings:
fig. 1 is a schematic diagram of a clamp circuit, according to an example embodiment.
Fig. 2 is a schematic diagram of an isolated drive circuit, according to an example embodiment.
Fig. 3 is a schematic diagram of a reverse withstand voltage circuit according to an exemplary embodiment.
Description of the reference numerals
A 10-clamp circuit; a 20-analog optocoupler circuit; 30-isolating the driving circuit; 11-a reverse withstand voltage circuit; 12-a low temperature drift circuit; 121-positive temperature coefficient branch; 122-negative temperature coefficient branch; 123-a feedback branch; 13-an overcharge prevention circuit; a 21-isolation switching circuit; 31-a driving circuit.
Detailed Description
The following describes specific embodiments of the present invention in detail with reference to the drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
In the following description, the words "first," "second," and the like are used merely for distinguishing between the descriptions and not for indicating or implying a relative importance or order.
During signal transmission, an optocoupler can be used for signal transmission, for example, when current flows from the anode to the cathode, the light-emitting diode of the optocoupler can emit light, so that the phototriode at the other side of the optocoupler receives an optical signal, and signal isolation transmission is realized.
The clamping circuit is a common electronic circuit and has wide application fields, such as signal amplitude limiting, power supply voltage stabilization, temperature compensation, waveform trimming, voltage detection and the like. Clamping circuits are often used to limit an input voltage signal to a fixed voltage range to ensure a stable operating voltage, which is important for precision measurement instruments and computer systems that require high voltage.
In addition, in some occasions where some optocouplers are replaced, the clamping circuit is also important. In the related art, the optical coupler is adopted for signal transmission, so that the problems of light attenuation, slow transmission rate, high error rate and the like exist. Therefore, there is a need to design an alternative optocoupler, and the core idea of the alternative optocoupler is to form the optocoupler voltage, i.e. to stabilize the output voltage at the forward turn-on voltage from the anode to the cathode of the light emitting diode in the optocoupler circuit.
In order to solve the above technical problems, the inventor designs a clamping circuit, which clamps the voltage between the anode and the cathode through a low temperature drift circuit, and reduces overshoot when the voltage between the anode and the cathode suddenly changes through an overcharge prevention circuit, so as to output a clamping voltage signal stabilized at an optocoupler voltage value.
Referring to fig. 1 and 2, fig. 1 is a schematic diagram of a clamping circuit according to an exemplary embodiment. Fig. 2 is a schematic diagram of an isolated drive circuit, according to an example embodiment.
The clamp circuit 10 may include a low temperature drift circuit 12 and an overcharge prevention circuit 13, the low temperature drift circuit 12 and the overcharge prevention circuit 13 being coupled. Other circuits in the clamp circuit 10 may be set according to practical situations, and embodiments of the present invention are not limited herein.
The low temperature drift circuit 12 has a positive input end and a negative input end, receives an input voltage signal through the positive input end and the negative input end of the low temperature drift circuit 12, and clamps the input voltage signal to obtain an output voltage signal of the low temperature drift circuit 12, where the low temperature drift circuit 12 may include a positive temperature coefficient branch 121 and a negative temperature coefficient branch 122 connected in series, and the output voltage signal of the low temperature drift circuit 12 is a sum of the voltage signal at two ends of the positive temperature coefficient branch 121 and the voltage signal at two ends of the negative temperature coefficient branch 122.
The low temperature drift circuit 12 may be a circuit with a low temperature drift coefficient, even close to a zero temperature coefficient, and the output voltage signal of the low temperature drift circuit 12 is less affected by temperature because the positive and negative temperature coefficients set by the low temperature drift circuit 12 can cancel each other.
The positive input end and the negative input end of the low temperature drift circuit 12 are coupled to a power supply to receive an input voltage signal, the positive input end of the low temperature drift circuit 12 is connected to the positive electrode (anode) of the power supply, and the negative input end of the low temperature drift circuit 12 is connected to the negative electrode (cathode) of the power supply.
The low temperature drift circuit 12 performs clamping processing based on the input voltage signal, and locks the voltage value of the output voltage signal, that is, the clamping voltage value. When the voltage at the positive input terminal of the low temperature drift circuit 12 is greater than the voltage at the negative input terminal of the low temperature drift circuit 12, the voltage value of the output voltage signal of the low temperature drift circuit 12 is the clamping voltage value.
The low temperature drift circuit 12 includes a positive temperature coefficient branch 121 and a negative temperature coefficient branch 122 connected in series, the positive temperature coefficient branch 121 generates a positive temperature coefficient voltage signal, the negative temperature coefficient branch 122 generates a negative temperature coefficient voltage signal, and the output voltage signal of the low temperature drift circuit 12 is the sum of the positive temperature coefficient voltage signal and the negative temperature coefficient voltage signal. The positive temperature coefficient voltage signal generated by the positive temperature coefficient branch 121 increases as the temperature increases, and the negative temperature coefficient voltage signal generated by the negative temperature coefficient branch 122 decreases as the temperature increases.
Thus, by adjusting the parameters in the positive temperature coefficient branch 121 and the negative temperature coefficient branch 122, the low temperature drift circuit 12 can have a lower temperature drift coefficient, even close to a zero temperature coefficient, i.e. less affected by temperature, so that the accuracy of the output voltage signal is improved.
The overcharge prevention circuit 13 is coupled to the low temperature drift circuit 12, receives the output voltage signal of the low temperature drift circuit 12, and performs overcharge prevention processing on the output voltage signal of the low temperature drift circuit 12 to obtain a clamp voltage signal.
When the voltages of the anode and the cathode are suddenly changed, the output voltage signal is clamped, and the clamping voltage signal is obtained.
Through the above technical scheme, the clamping circuit 10 includes the low temperature drift circuit 12 and the overcharge prevention circuit 13, and receives an input voltage signal through the positive input end and the negative input end of the low temperature drift circuit 12, clamps the input voltage signal to obtain an output voltage signal of the low temperature drift circuit 12, and then receives the output voltage signal of the low temperature drift circuit 12 through the overcharge prevention circuit 13, and performs overcharge prevention on the output voltage signal of the low temperature drift circuit 12 to obtain a clamping voltage signal. The low temperature drift circuit 12 clamps the voltage between the anode and the cathode, and the overcharge prevention circuit 13 reduces overshoot when the voltage between the anode and the cathode suddenly changes, thereby outputting a clamp voltage signal stabilized at a preset voltage value. In one embodiment, the predetermined voltage value includes a turn-on voltage drop value of the light emitting diode in the optocoupler circuit.
In one possible implementation, the clamping circuit 10 further includes: reverse withstand voltage circuit 11.
The reverse voltage-resistant circuit 11 is coupled to a power supply, and the reverse voltage-resistant circuit 11 is coupled to the low temperature drift circuit 12, and the reverse voltage-resistant circuit 11 performs reverse bias cut-off processing on an input voltage signal provided by the received power supply and transmits the input voltage signal to the low temperature drift circuit 12. The "reverse bias cutoff" here is: when the input voltage signal is a positive voltage, that is, when the voltage of the positive electrode of the power supply is higher than the voltage of the negative electrode of the power supply, the reverse withstand voltage circuit 11 transmits the input voltage signal to the input terminal of the low temperature drift circuit 12; when the input voltage signal is a negative voltage, that is, the voltage of the positive electrode of the power supply is lower than the voltage of the negative electrode of the power supply, the reverse voltage-withstanding circuit 11 is turned off, and the input voltage signal is not transmitted to the input terminal of the low temperature drift circuit 12.
The low temperature drift circuit 12 is coupled to a power supply through the reverse voltage withstanding circuit 11, and the reverse voltage withstanding circuit 11 is coupled to the power supply to receive an input voltage signal provided by the power supply. Specifically, the reverse withstand voltage circuit 11 is coupled to a power supply positive electrode and a power supply negative electrode to receive an input voltage signal.
The reverse withstand voltage circuit 11 prevents the voltage of the negative electrode of the power supply supplied by the power supply from being higher than the voltage of the positive electrode of the power supply. In one embodiment, the reverse withstand voltage circuit 11 exhibits a reverse bias cut-off characteristic of an analog optocoupler.
In one possible embodiment, the reverse withstand voltage circuit 11 includes: first MOS transistor M1.
The first MOS tube M1 is provided with a first end, a control end and a second end. The first end of the first MOS tube M1 is coupled to the positive electrode of the power supply, the control end of the first MOS tube M1 is coupled to the negative input end of the low temperature drift circuit 12, and the second end of the first MOS tube M1 is coupled to the positive input end of the low temperature drift circuit 12.
For example, the first end of the first MOS transistor M1 is a source, coupled to the positive electrode of the power supply, the control end of the first MOS transistor M1 is a gate, coupled to the negative electrode of the power supply and the negative input end of the low temperature drift circuit 12, and the second end of the first MOS transistor M1 is a drain, coupled to the positive input end of the low temperature drift circuit 12.
The first MOS transistor M1 may be a PMOS transistor. The PMOS transistor is of a low-level conductive characteristic, and when the negative electrode of the power supply is connected to a low level, the first MOS transistor M1 is turned on to transmit the current of the positive electrode of the power supply to the low-temperature drift circuit 12. If the voltage of the negative electrode of the power supply is higher than the voltage of the positive electrode of the power supply, the first MOS tube M1 is turned off, and no current exists in the first MOS tube M1. Therefore, the first MOS tube M1 can simulate the reverse bias cut-off characteristic of the optocoupler.
Fig. 3 is a schematic diagram of a reverse withstand voltage circuit according to an exemplary embodiment. In the embodiment shown in fig. 3, the reverse withstand voltage circuit 11 further includes: and a second MOS transistor M2.
The second MOS transistor M2 has a first end, a control end and a second end. The first end of the second MOS transistor M2 is coupled to the second end of the first MOS transistor M1, and the control end of the second MOS transistor M2 and the second end of the second MOS transistor M2 are both coupled to the negative input end of the low temperature drift circuit 12. The second MOS transistor M2 may be an NMOS transistor, and the second MOS transistor M2 includes an electrostatic discharge (Electro Static discharge, ESD) MOS transistor. When the voltage between the positive electrode and the negative electrode of the power supply suddenly increases to generate electrostatic pulse, the parasitic triode formed by the drain electrode, the body region and the source electrode of the second MOS tube M2 is conducted and has reverse breakdown and secondary breakdown, so that current flows from the positive electrode to the negative electrode of the power supply to discharge static electricity, and electrostatic protection of the clamping circuit 10 is realized. In addition, in the embodiment shown in fig. 3, the parasitic diode DP1 of the first MOS transistor M1 and the parasitic diode DN1 of the second MOS transistor M2 are also illustrated.
When the anode voltage is lower than the cathode voltage, the first MOS transistor M1 is turned off. The parasitic diode DP1 of the first MOS transistor M1 and the parasitic diode DN1 of the second MOS transistor M2 are connected in series, so as to realize high reverse withstand voltage. By adjusting the sizes of the first MOS tube M1 and the second MOS tube M2, the ESD protection capability can be enhanced.
In one possible implementation, the ptc branch 121 includes: a first resistor R1.
The first end of the first resistor R1 is coupled to the positive input end of the low temperature drift circuit 12, and the second end of the first resistor R1 is coupled to the negative temperature coefficient branch 122, wherein the first resistor R1 is a zero temperature coefficient resistor.
The zero temperature coefficient resistor may be a resistor whose resistance value is not affected by temperature.
In one possible implementation, the ptc branch 121 further comprises: an adjustable resistor Rx;
the first resistor R1 and the adjustable resistor Rx are coupled in series between the positive input terminal of the low temperature drift circuit 12 and the negative temperature coefficient branch 122, wherein the adjustable resistor Rx is a positive temperature coefficient resistor.
The positive temperature coefficient resistor may be a resistor having a resistance value that increases as the temperature increases.
Illustratively, a first end of the first resistor R1 is coupled to the positive input end of the low temperature drift circuit 12, and a second end of the first resistor R1 is coupled to the negative temperature coefficient branch 122 through the adjustable resistor Rx. The first end of the adjustable resistor Rx is coupled to the second end of the first resistor R1, and the second end of the adjustable resistor Rx is coupled to the negative temperature coefficient branch 122.
In other embodiments, a first end of the adjustable resistor Rx is coupled to the positive input end of the low temperature drift circuit 12, and a second end of the adjustable resistor Rx is coupled to the negative temperature coefficient branch 122 through the first resistor R1. The first end of the first resistor R1 is coupled to the second end of the adjustable resistor Rx, and the second end of the first resistor R1 is coupled to the negative temperature coefficient branch 122.
By setting the adjustable resistor Rx, the ptc voltage signal generated by the ptc branch 121 can be adjusted, thereby adjusting the output voltage signal.
In one possible implementation, the negative temperature coefficient branch 122 includes: a first transistor Q1, a second transistor Q2, a third transistor Q3, and a second resistor R2.
The base of the first transistor Q1 is connected to the base of the second transistor Q2, the base of the first transistor Q1 is connected to the collector of the first transistor Q1, the emitter of the first transistor Q1 is coupled to the emitter of the second transistor Q2, the emitter of the first transistor Q1 and the emitter of the second transistor Q2 are both coupled to the negative input terminal of the low temperature drift circuit 12, and the collector of the first transistor Q1 is coupled to the positive temperature coefficient branch 121.
The base of the third transistor Q3 is coupled to the collector of the first transistor Q1, the emitter of the third transistor Q3 is coupled to the first end of the second resistor R2, and the second end of the second resistor R2 is coupled to the emitter of the second transistor Q2.
Since the voltage between the base and emitter of the transistor decreases with increasing temperature, the transistor is a negative temperature coefficient device. In this embodiment, the voltage between the base and the emitter of the first transistor Q1 is a negative temperature coefficient, the voltage between the base and the emitter of the second transistor Q2 is a negative temperature coefficient, and the voltage between the base and the emitter of the third transistor Q3 is a negative temperature coefficient. Since the base of the first transistor Q1, the base of the second transistor Q2, and the base of the third transistor Q3 are connected, the voltages of the base of the first transistor Q1, the base of the second transistor Q2, and the base of the third transistor Q3 are equal.
Specifically, the output voltage signal of the low temperature drift circuit is the sum of the positive temperature coefficient voltage signal and the negative temperature coefficient voltage signal, and the calculation formula of the output voltage signal of the low temperature drift circuit is:
wherein,an output voltage signal representing a low temperature drift circuit, < >>Characterizing a positive temperature coefficient voltage signal, ">The negative temperature coefficient voltage signal is characterized.
The positive temperature coefficient branch 121 includes a first resistor R1 and an adjustable resistor Rx, and the positive temperature coefficient voltage signal has the following formula:
wherein,characterizing the voltage across the first resistor R1, < >>The voltage across the adjustable resistor Rx is characterized.
Since the base and collector of the first transistor Q1 are connected, the base voltage of the first transistor Q1 is the collector voltage of the first transistor Q1, and the voltage between the base and emitter of the first transistor Q1 is equal to the voltage between the collector and emitter of the first transistor Q1.
The negative temperature coefficient voltage signal generated by the negative temperature coefficient branch 122 has the following expression:
wherein,the voltage between the base and emitter of the first transistor Q1 is characterized.
The sum of the voltage between the base and the emitter of the third transistor Q3 and the voltage across the second resistor R2 is equal to the voltage across the base and the emitter of the second transistor Q2, and then the voltage across the second resistor R2 is calculated as:
wherein,characterizing the voltage across the second resistor R2, < >>Characterizing the voltage between the base and emitter of the second transistor Q2,/v>The voltage between the base and emitter of the third transistor Q3 is characterized.
The voltage between the base and emitter of the second transistor Q2 is a negative temperature coefficient, and the voltage between the base and emitter of the third transistor Q3 is a negative temperature coefficient, by providing the second transistor Q2 and the third transistor Q3 to be different in size, the voltage difference between the bases and emitters of the two transistorsIs a positive temperature coefficient and is positively correlated with temperature.
Since the second resistor R2 and the third transistor Q3 are connected in series, the current flowing through the second resistor R2 is equal to the current flowing through the third transistor Q3, and is also equal to the current flowing through the second transistor Q2 and the current flowing through the first transistor Q1, and the expression of the current flowing through the second resistor R2 is:
wherein,characterizing the current through the second resistor R2, < >>Characterizing the resistance of the second resistor R2, < >>Characterizing the current through the third transistor Q3,/v>Characterizing the current through the second transistor Q2,/v>The current through the first transistor Q1 is characterized.
The current flowing through the first resistor R1 is split into the first transistor Q1, the second transistor Q2 and the third transistor Q3, and the current flowing through the first resistor R1 has the following formula:
wherein,the current through the first resistor R1 is characterized and β characterizes the transistor amplification.
In summary, the positive temperature coefficient voltage signal has the following formula:
from positive temperature coefficient voltage signalsAs can be seen from the expression of (1), the current flowing through the first transistor Q1 +.>Current through the second transistor Q2 +.>And current +.>All have positive temperature coefficient, positive temperature coefficient voltage signal +.>Also has positive temperature coefficient, and can also be controlled by adjusting adjustable resistance R X Is to adjust the positive temperature coefficient voltage signal +.>So that the positive temperature coefficient voltage signal +.>Positive temperature coefficient and negative temperature coefficient voltage signal +.>The negative temperature coefficient of the output voltage signal is realized, even zero temperature coefficient. In one embodiment, the output voltage signal generated by the clamping circuit 10 can solve the problem that the optocoupler varies greatly with temperature.
In one possible implementation, the low temperature drift circuit 12 has a positive output and a negative output, the low temperature drift circuit 12 further includes a feedback branch 123, the feedback branch 123 including: the third MOS tube M3, the fourth MOS tube M4, the fifth MOS tube M5 and the first capacitor C1.
The first end of the third MOS transistor M3 is coupled to the positive temperature coefficient branch 121, the first end of the third MOS transistor M3 is coupled to the first end of the fourth MOS transistor M4, the control end of the third MOS transistor M3 is connected to the control end of the fourth MOS transistor M4, the second end of the third MOS transistor M3 is connected to the control end of the third MOS transistor M3, the second end of the third MOS transistor M3 is coupled to the collector of the second transistor Q2, and the second end of the fourth MOS transistor M4 is coupled to the collector of the third transistor Q3.
Illustratively, the first end of the third MOS transistor M3 is coupled to the first end of the first resistor R1.
The first end of the first capacitor C1 is coupled to the first end of the fourth MOS transistor M4, and the second end of the first capacitor C1 is coupled to the control end of the fifth MOS transistor M5.
The control end of the fifth MOS transistor M5 is coupled to the second end of the fourth MOS transistor M4, the first end of the fifth MOS transistor M5 is coupled to the first end of the first capacitor C1, the first end of the fifth MOS transistor M5 is coupled to the positive output end of the low temperature drift circuit 12, the second end of the fifth MOS transistor M5 is coupled to the second end of the second resistor R2, and the second end of the fifth MOS transistor M5 is coupled to the negative output end of the low temperature drift circuit 12.
The voltage value of the collector of the second transistor Q2 and the voltage value of the collector of the third transistor Q3 are regulated by the feedback branch 123.
In other embodiments, the second end of the third MOS transistor M3 may be coupled to the collector of the second transistor Q2 through a resistor, and the second end of the fourth MOS transistor M4 may be coupled to the collector of the third transistor Q3 through another resistor.
In one possible embodiment, the overcharge prevention circuit 13 has a positive output terminal and a negative output terminal, and the clamp voltage signal is outputted through the positive output terminal and the negative output terminal of the overcharge prevention circuit 13.
The overcharge prevention circuit 13 may include: the MOS transistor comprises a sixth MOS transistor M6, a seventh MOS transistor M7, an eighth MOS transistor M8, a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a second capacitor C2.
The first end of the third resistor R3 is coupled to the first end of the fifth MOS transistor M5, the second end of the third resistor R3 is coupled to the first end of the sixth MOS transistor M6, the second end of the sixth MOS transistor M6 is coupled to the second end of the fifth MOS transistor M5, and the control end of the sixth MOS transistor M6 is coupled to the second end of the first capacitor C1.
The first end of the seventh MOS transistor M7 is coupled to the first end of the third resistor R3, and the control end of the seventh MOS transistor M7 is coupled to the second end of the third resistor R3.
The first end of the eighth MOS transistor M8 is coupled to the first end of the seventh MOS transistor M7, the second end of the eighth MOS transistor M8 is coupled to the first end of the fourth resistor R4, the second end of the fourth resistor R4 is coupled to the control end of the sixth MOS transistor M6, the second end of the fourth resistor R4 is coupled to the control end of the fifth MOS transistor M5, and the control end of the eighth MOS transistor M8 is coupled to the second end of the seventh MOS transistor M7.
The first end of the fifth resistor R5 is coupled to the first end of the eighth MOS transistor M8, the first end of the fifth resistor R5 is coupled to the positive output end of the overcharge protection circuit 13, the second end of the fifth resistor R5 is coupled to the first end of the second capacitor C2, the second end of the fifth resistor R5 is coupled to the control end of the eighth MOS transistor M8, the second end of the second capacitor C2 is coupled to the second end of the sixth MOS transistor M6, and the second end of the second capacitor C2 is coupled to the negative output end of the overcharge protection circuit 13.
The specific working procedure of the overcharge prevention circuit 13 is as follows:
when the voltage between the anode and the cathode suddenly changes, the voltage drop will be generated at the two ends of the fifth resistor R5, so that the eighth MOS transistor M8 is turned on, and the control end of the fifth MOS transistor M5 is charged through the fourth resistor R4, and when the voltage of the control end of the fifth MOS transistor M5 is raised to be on, the voltage between the anode and the cathode is clamped, so as to reduce the overshoot.
And when the voltage of the control end of the sixth MOS transistor M6 increases to be on, the sixth MOS transistor M6 flows through current, and the third resistor R3 generates voltage drop, so that the seventh MOS transistor M7 is on, the fifth resistor R5 is short-circuited, and the eighth MOS transistor M8 is turned off, so that the normal operation of the low-temperature drift circuit 12 is not affected.
The third resistor R3 and the sixth MOS transistor M6 are current detection circuits of the fifth MOS transistor M5.
In fig. 1 and fig. 3, the control end of the MOS transistor refers to the gate of the MOS transistor, and the first end and the second end refer to the source or the drain of the MOS transistor, and specific types and parameters of the MOS transistor, and corresponding conditions of each electrode may be set according to actual use conditions, which is not limited in the embodiments of the present invention.
Further, on the basis of the above embodiment, the embodiment of the present invention further provides an analog optocoupler circuit 20, where the analog optocoupler circuit 20 includes a clamp circuit 10 and an isolation conversion circuit 21.
The clamping circuit 10 inputs a pulse width modulation signal. The pulse width modulation signal comprises a high and low logic level signal, which can be modulated by a duty cycle. The pulse width modulation signal may be 0V and 5V, or positive 10V and negative 10V, for example. In one embodiment, the negative input of the low temperature drift circuit 12 may also be grounded.
The isolation conversion circuit 21, the isolation conversion circuit 21 is coupled with the clamp circuit 10, and the isolation conversion circuit 21 is used for electrically isolating the clamp voltage signal output by the clamp circuit 10 and outputting a control signal, wherein the control signal characterizes the clamp voltage signal.
The isolation switch 21 may be composed of an oscillator and an isolation capacitor, and provides a stable ac signal source through the oscillator to generate an output signal with continuous oscillation. The isolation capacitor provides electrical isolation to avoid direct transfer of current and interfering signals.
Further, on the basis of the above embodiment, the embodiment of the present invention further provides an isolation driving circuit 30, where the isolation driving circuit 30 includes the clamp circuit 10, the isolation conversion circuit 21, and the driving circuit 31.
The clamping circuit 10 inputs a pulse width modulation signal.
The isolation conversion circuit 21, the isolation conversion circuit 21 is coupled with the clamp circuit 10, and the isolation conversion circuit 21 is used for electrically isolating the clamp voltage signal output by the clamp circuit 10 and outputting a control signal, wherein the control signal characterizes the clamp voltage signal.
The driving circuit 31 is coupled to the isolation converting circuit 21, and the driving circuit 31 is configured to receive the control signal and generate a driving signal according to the control signal to drive the power switch to be turned on or off.
The power switch may be, but is not limited to, a metal semiconductor field effect transistor (Metal Oxide Semiconductor Field Effect Transistor, MOSFET), an insulated gate bipolar transistor (Insulated Gate Bipolar Transistor, IGBT), a bipolar junction transistor (bipolar junction transistor, BJT), etc.
Claims (10)
1. A clamping circuit, the clamping circuit comprising:
the low-temperature drift circuit is provided with a positive input end and a negative input end, receives an input voltage signal through the positive input end and the negative input end of the low-temperature drift circuit, clamps the input voltage signal to obtain an output voltage signal of the low-temperature drift circuit, and comprises a positive temperature coefficient branch and a negative temperature coefficient branch which are connected in series, wherein the output voltage signal of the low-temperature drift circuit is the sum of the voltage signals at two ends of the positive temperature coefficient branch and the voltage signals at two ends of the negative temperature coefficient branch;
and the overcharge prevention circuit is coupled with the low-temperature drift circuit, receives the output voltage signal of the low-temperature drift circuit, and performs overcharge prevention treatment on the output voltage signal of the low-temperature drift circuit to obtain a clamping voltage signal.
2. The clamp circuit of claim 1, wherein the positive temperature coefficient branch comprises: a first resistor;
the first end of the first resistor is coupled with the positive input end of the low temperature drift circuit, and the second end of the first resistor is coupled with the negative temperature coefficient branch circuit, wherein the first resistor is a zero temperature coefficient resistor.
3. The clamping circuit of claim 2, wherein the positive temperature coefficient branch further comprises: an adjustable resistor;
the first resistor and the adjustable resistor are coupled in series between the positive input end of the low temperature drift circuit and the negative temperature coefficient branch, wherein the adjustable resistor is a positive temperature coefficient resistor.
4. The clamp circuit of claim 1, wherein the negative temperature coefficient branch comprises: a first transistor, a second transistor, a third transistor, and a second resistor;
the base electrode of the first transistor is connected with the base electrode of the second transistor, the base electrode of the first transistor is connected with the collector electrode of the first transistor, the emitter electrode of the first transistor is coupled with the emitter electrode of the second transistor, the emitter electrodes of the first transistor and the second transistor are both coupled with the negative input end of the low-temperature drift circuit, and the collector electrode of the first transistor is coupled with the positive temperature coefficient branch circuit;
the base of the third transistor is coupled to the collector of the first transistor, the emitter of the third transistor is coupled to the first end of the second resistor, and the second end of the second resistor is coupled to the emitter of the second transistor.
5. The clamp circuit of claim 4, wherein the low temperature drift circuit has a positive output and a negative output, the low temperature drift circuit further comprising a feedback leg comprising: the third MOS transistor, the fourth MOS transistor, the fifth MOS transistor and the first capacitor;
the first end of the third MOS tube is coupled with the positive temperature coefficient branch, the first end of the third MOS tube is coupled with the first end of the fourth MOS tube, the control end of the third MOS tube is connected with the control end of the fourth MOS tube, the second end of the third MOS tube is connected with the control end of the third MOS tube, the second end of the third MOS tube is coupled with the collector electrode of the second transistor, and the second end of the fourth MOS tube is coupled with the collector electrode of the third transistor;
the first end of the first capacitor is coupled with the first end of the fourth MOS tube, and the second end of the first capacitor is coupled with the control end of the fifth MOS tube;
the control end of the fifth MOS tube is coupled with the second end of the fourth MOS tube, the first end of the fifth MOS tube is coupled with the first end of the first capacitor, the first end of the fifth MOS tube is coupled with the positive output end of the low-temperature drift circuit, the second end of the fifth MOS tube is coupled with the second end of the second resistor, and the second end of the fifth MOS tube is coupled with the negative output end of the low-temperature drift circuit.
6. The clamp circuit of claim 5, wherein the anti-overcharge circuit has a positive output terminal and a negative output terminal through which the clamp voltage signal is output;
the overcharge prevention circuit includes: the third MOS transistor, the fourth MOS transistor, the fifth MOS transistor and the third resistor are connected with the first capacitor;
the first end of the third resistor is coupled with the first end of the fifth MOS tube, the second end of the third resistor is coupled with the first end of the sixth MOS tube, the second end of the sixth MOS tube is coupled with the second end of the fifth MOS tube, and the control end of the sixth MOS tube is coupled with the second end of the first capacitor;
the first end of the seventh MOS tube is coupled with the first end of the third resistor, and the control end of the seventh MOS tube is coupled with the second end of the third resistor;
the first end of the eighth MOS tube is coupled with the first end of the seventh MOS tube, the second end of the eighth MOS tube is coupled with the first end of the fourth resistor, the second end of the fourth resistor is coupled with the control end of the sixth MOS tube, the second end of the fourth resistor is coupled with the control end of the fifth MOS tube, and the control end of the eighth MOS tube is coupled with the second end of the seventh MOS tube;
the first end of the fifth resistor is coupled to the first end of the eighth MOS tube, the first end of the fifth resistor is coupled to the positive output end of the overcharge-preventing circuit, the second end of the fifth resistor is coupled to the first end of the second capacitor, the second end of the fifth resistor is coupled to the control end of the eighth MOS tube, the second end of the second capacitor is coupled to the second end of the sixth MOS tube, and the second end of the second capacitor is coupled to the negative output end of the overcharge-preventing circuit.
7. The clamp circuit of claim 1, wherein the clamp circuit further comprises: a reverse withstand voltage circuit;
the reverse voltage-resistant circuit is coupled with a power supply, is coupled with the low-temperature drift circuit, and performs reverse bias cut-off processing on an input voltage signal provided by the received power supply and transmits the input voltage signal to the low-temperature drift circuit.
8. The clamp circuit of claim 7, wherein the reverse withstand voltage circuit comprises: the first MOS tube and the second MOS tube;
the first end of the first MOS tube is coupled with the positive electrode of the power supply, the control end of the first MOS tube is coupled with the negative input end of the low-temperature drift circuit, and the second end of the first MOS tube is coupled with the positive input end of the low-temperature drift circuit;
the first end of the second MOS tube is coupled with the second end of the first MOS tube, and the control end of the second MOS tube and the second end of the second MOS tube are coupled with the negative input end of the low-temperature drift circuit.
9. An analog optocoupler circuit, the analog optocoupler circuit comprising:
the clamping circuit of any one of claims 1-8, wherein the input voltage signal is a pulse width modulation signal;
and the isolation conversion circuit is coupled with the clamping circuit and is used for electrically isolating the clamping voltage signal output by the clamping circuit and outputting a control signal, and the control signal characterizes the clamping voltage signal.
10. An isolated drive circuit, the isolated drive circuit comprising:
the clamping circuit of any one of claims 1-8, wherein the input voltage signal is a pulse width modulation signal;
the isolation conversion circuit is coupled with the clamping circuit and is used for electrically isolating the clamping voltage signal output by the clamping circuit and outputting a control signal, and the control signal characterizes the clamping voltage signal;
the driving circuit is coupled with the isolation conversion circuit and is used for receiving the control signal and generating a driving signal according to the control signal so as to drive the power switch to be turned on and turned off.
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| CN202311763395.6A CN117439593B (en) | 2023-12-21 | 2023-12-21 | Clamping circuit, analog optocoupler circuit and isolation driving circuit |
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| CN202311763395.6A CN117439593B (en) | 2023-12-21 | 2023-12-21 | Clamping circuit, analog optocoupler circuit and isolation driving circuit |
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| CN117439593A (en) | 2024-01-23 |
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