CN101800481A - Feedback control method of isolating feedback power supply and isolating feedback power supply - Google Patents
Feedback control method of isolating feedback power supply and isolating feedback power supply Download PDFInfo
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Abstract
The invention discloses a feedback control method of an isolating feedback power supply and an isolating feedback power supply. The power supply comprises a sampling circuit, a photoelectric coupled device, a voltage dividing resistor, a mirror current circuit and a regulating circuit, wherein the sampling circuit is used for sampling the voltage of an output end of a transformer and converting the voltage into the primary input current of the photoelectric coupled device; the photoelectric coupled device is used for converting the primary input current into secondary output current; the voltage dividing resistor is connected with one end of the secondary stage of the photoelectric coupled device and the regulating circuit and is used for converting the secondary output current of the photoelectric coupled device into the pin voltage of the regulating circuit; the mirror current circuit is connected with the other end of the photoelectric coupled device and the regulating circuit and is used for maintaining a linear proportional relationship between the primary input current and the secondary output current of the photoelectric coupled device; and the regulating circuit is used for regulating the energy of the transformer transmitted from the input end to the output end according to the pin voltage. The power supply ensures the linear proportional relationship between the pin voltage of the regulating circuit and the sampling voltage by the mirror current circuit, and enhances the bandwidth of a feedback circuit.
Description
Technical Field
The invention relates to the technical field of electronics, in particular to an isolated feedback power supply feedback control method for improving the bandwidth of an isolated feedback power supply and an isolated feedback power supply.
Background
Isolated power supplies are a common type of power supplies in switching power supply technology, and usually include isolated power supplies such as alternating current-direct current (ACDC) or direct current-direct current (DCDC).
Fig. 1 is a schematic circuit diagram of an isolated feedback power supply of one of the topologies. As shown in FIG. 1, the isolated feedback power supply input voltage V1Input terminal and output voltage VoutAnd the output end is isolated by a transformer. The power control chip (IC) controls the amount of energy in the transformer that is transferred from the primary (input) to the secondary (output) by adjusting the on-duty cycle of the switching transistor Q1.
In order to ensure the output voltage of the isolated feedback power supply to be stable, the output voltage V needs to be adjustedoutSampling is carried out, and the data is fed back to the power supply control chip in an isolation type feedback mode. The photocoupler (short for photocoupler) isolated on the electric appliance shown in fig. 1 is provided for realizing the above sampling. The primary (ends a and k) of the optocoupler are light emitting diodes, the secondary (ends c and e) of the optocoupler are phototriodes, and the ends a and k are not electrically connected with the ends c and e and are electrically isolated. At the primary of the optical coupler, to output voltage VoutAfter sampling, the voltage is divided by resistors R3 and R4 and then linearly converted into a current I flowing between two ends of a primary stage a and a primary stage kakI, flowing between the ends of a, kakThe current generates light to the phototriode. After a voltage V2 is applied to the two ends c and e of the phototriode on the secondary side of the optocoupler, a current I is formed between the two ends c and eceCurrent I flowing through the secondary of the optocouplerceThe voltage V of the FB pin of the power supply control chip is formed by a resistor R1 which is groundedFB. And IakAnd IceWhen the optical coupler works in an amplification region, the optical coupler is in linear proportional relation, so that voltage V sampled from an output endoutAnd the voltage V of the FB pin of the power control chipFBAnd the linear proportionality is also realized, so that the isolated feedback from the output end sampling voltage to the pin voltage of the power supply control chip is realized.
Fig. 2 is a schematic diagram of an equivalent principle of sampling an output voltage of a conventional isolated feedback power supply circuit. The method comprises the following steps:
1. the output voltage is sampled.
Obtaining voltage V of sampling pointout。
2. And converting the voltage obtained by sampling into current.
In which the voltage V sampled from the output terminal is measuredoutThe output of the circuit with the same function through LT431 or built-up is the current which flows through the primary of the optical coupler in a linear relation.
3. And the current-photocurrent isolation conversion is realized through an optical coupler.
4. And the secondary of the optical coupler obtains output current.
Because the secondary of the optical coupler has larger capacitance, the current output by the secondary is influenced by the capacitance of the optical coupler. Its action on the output current is similar to that of an RC filter circuit, as shown in fig. 2, with a signal frequency higher than that of the RC filter circuit
The gain will be largely filtered by the capacitance C (i.e., the equivalent capacitance C1 of the optocoupler itself).
Due to the inherent capacitance of the photocoupler device, the circuit of the photocoupler part is equivalent to the circuit shown in fig. 3. The capacitance C1 in FIG. 3 is the equivalent capacitance between the two ends C and e of the optical coupler formed by the capacitive property of the optical coupler, when the voltage changes, the current I of the secondary side of the optical couplerceThe capacitors need to be charged and discharged, so that the change of the current between the two ends C and e is completely filtered by the capacitor C1, and the change of the voltage of the FB pin cannot reflect the change of the current between the two sections a and k, so that the change of the voltage of the FB pin cannot be in linear proportion with the change of the sampling voltage, and the bandwidth of the optical coupler is limited by the self-capacitance of the optical coupler.
5. The conversion of the current of the secondary side of the optocoupler into voltage.
The current of the secondary side of the optical coupler is converted into the voltage of the FB pin of the power control chip through a grounding resistor.
It can be seen that, in the above-mentioned existing isolated feedback power supply circuit, because there is an influence similar to the capacitance of the filter circuit in the feedback path, the current between the two ends c and e of the optocoupler secondary needs to charge and discharge its equivalent capacitor, resulting in the current at the two ends c and e being consumed by the equivalent capacitor, so that the change of the voltage output to the FB end cannot reflect the change of the current at the input end between the two sections a and k, thereby limiting the bandwidth of the sampling feedback circuit, and making the dynamic response of the isolated feedback power supply not high. That is to say, the equivalent capacitance of the optocoupler has a very large influence on the feedback path of the isolated feedback power supply, and in order to reduce the influence of the optocoupler capacitance and obtain the rated dynamic response requirement, more capacitors need to be connected in parallel at the output end of the power supply, and meanwhile, a high-speed optocoupler needs to be selected, but the effect is not obvious. And the use cost of the parallel capacitor and the high-speed optocoupler is very high, and the volume of the isolated feedback power supply circuit is very large.
Disclosure of Invention
The invention provides an isolated feedback power supply feedback control method and an isolated feedback power supply, which are used for solving the problem of low dynamic response caused by the fact that the capacitive property of a photoelectric coupling device influences the bandwidth of a feedback path of the isolated feedback power supply in the prior art.
The invention comprises the following contents:
an isolated feedback power supply comprising: transformer, sampling circuit, optoelectronic coupling device, adjusting circuit still include: a mirror current circuit and a voltage dividing resistor;
the sampling circuit is used for sampling the voltage at the output end of the transformer and converting the voltage into primary input current of the photoelectric coupling device;
the photoelectric coupling device is used for converting primary input current into secondary output current;
the voltage dividing resistor is connected with one end of the secondary of the photoelectric coupling device and the adjusting circuit and is used for converting the output current of the secondary of the photoelectric coupling device into the pin voltage of the adjusting circuit;
the mirror current circuit is connected with the other end of the secondary of the photoelectric coupling device and the adjusting circuit and is used for maintaining the linear proportional relation between the input current of the primary of the photoelectric coupling device and the output current of the secondary;
and one end of the adjusting circuit is connected with the mirror current circuit and the divider resistor, and the other end of the adjusting circuit is connected with the input end of the transformer and is used for adjusting the energy transferred from the input end to the output end of the transformer according to the pin voltage.
A method of isolated feedback power supply feedback control, comprising:
the sampling circuit samples the voltage at the output end of the transformer and converts the voltage into primary input current of a photoelectric coupling device;
the primary input current generates secondary output current through the photoelectric coupling device, and the linear proportional relation between the primary input current and the secondary output current of the photoelectric coupling device is maintained through a mirror current circuit connected with the secondary of the photoelectric coupling device;
converting the output current of the secondary to the pin voltage of an adjusting circuit connected with the mirror current circuit through a mirror current circuit and a divider resistor connected with the secondary of the photoelectric coupler;
and the adjusting circuit adjusts the energy transmitted from the input end to the output end of the transformer according to the pin voltage.
The invention has the following beneficial effects:
the invention provides an isolated feedback power supply feedback control method and an isolated feedback power supply, wherein the power supply comprises a transformer, a sampling circuit, a photoelectric coupling device, an adjusting circuit, a mirror current circuit and a divider resistor; the sampling circuit is used for sampling the voltage at the output end of the transformer and converting the voltage into primary input current of the photoelectric coupling device; the photoelectric coupling device is used for converting primary input current into secondary output current; the voltage dividing resistor is connected with one end of the secondary of the photoelectric coupling device and the adjusting circuit and is used for converting the output current of the secondary of the photoelectric coupling device into the pin voltage of the adjusting circuit; the mirror current circuit is connected with the other end of the secondary of the photoelectric coupling device and the adjusting circuit and is used for maintaining the linear proportional relation between the input current of the primary of the photoelectric coupling device and the output current of the secondary; and one end of the adjusting circuit is connected with the mirror current circuit and the divider resistor, and the other end of the adjusting circuit is connected with the input end of the transformer and is used for adjusting the energy transferred from the input end to the output end of the transformer according to the pin voltage. The linear proportional relation between the primary input current and the secondary output current of the photoelectric coupling device is maintained through the mirror current circuit, so that the linear proportional relation between the pin voltage of the adjusting circuit and the sampling voltage is guaranteed, the bandwidth of the feedback circuit is improved, the mode is low in implementation cost and high in reliability, and the high-frequency gain bandwidth can be effectively improved.
Drawings
FIG. 1 is a schematic diagram of a circuit structure of an isolated feedback power supply in the prior art;
FIG. 2 is a schematic diagram of the isolation feedback of an isolated switching power supply according to the prior art;
FIG. 3 is a schematic diagram of an equivalent circuit of an optocoupler portion of an isolated switching power supply in the prior art;
fig. 4 is a schematic structural diagram of an isolated switching power supply according to an embodiment of the present application;
FIG. 5 is a diagram illustrating an example of an isolated switching power supply according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of the isolation feedback of the isolated switching power supply according to the embodiment of the present application;
fig. 7 is a schematic diagram illustrating an operating principle of the mirror current circuit in the embodiment of the present application.
Detailed Description
To the problem that photoelectric coupling device self-capacitance influences the bandwidth of isolated feedback power supply feedback circuit among the above-mentioned prior art, this application embodiment provides an isolated feedback power supply, connects mirror current circuit and divider resistance between photoelectric coupling device's secondary and regulating circuit's power control chip to avoid photoelectric coupling device self-capacitance to the influence of the voltage of exporting the power control chip pin, improve isolated feedback power supply feedback circuit's bandwidth. The structure of the isolated feedback power supply is shown in fig. 4, and includes: the device comprises a transformer, a sampling circuit, a photoelectric coupler, a mirror current circuit, a divider resistor and an adjusting circuit.
And the sampling circuit is used for sampling the voltage at the output end of the transformer and converting the voltage into primary input current of the photoelectric coupling device.
And the photoelectric coupling device is used for converting the primary input current into the secondary output current.
And the divider resistor is connected with one end of the secondary of the photoelectric coupler and the adjusting circuit and is used for converting the output current of the secondary of the photoelectric coupler into the pin voltage of the adjusting circuit.
And the mirror current circuit is connected with the other end of the secondary of the photoelectric coupling device and the adjusting circuit and is used for maintaining the linear proportional relation between the primary input current and the secondary output current of the photoelectric coupling device.
And one end of the adjusting circuit is connected with the mirror current circuit and the divider resistor, and the other end of the adjusting circuit is connected with the input end of the transformer and is used for adjusting the energy transferred from the input end to the output end of the transformer according to the pin voltage.
Fig. 5 shows a specific circuit configuration example of the isolated feedback power supply shown in fig. 4.
FIG. 5 shows an isolated feedback power supply with a transformer input voltage V1The output voltage of the output end is Vout。
Preferably, an electrolytic capacitor C is connected in parallel between the two output terminals of the transformer output terminal.
One output terminal of the output end of the transformer is grounded, and the other output terminal which is not grounded can be connected with a diode L2 in series for ensuring the unidirectional conduction of the current at the output end.
The sampling circuit of the isolated feedback power supply specifically comprises: a resistor R2, a resistor R3, a resistor R4 and a shunt reference source L1. Wherein,
the resistor R3 is connected with the resistor R4 in series, the resistor R3 is connected with the output end of the transformer, and the resistor R4 is grounded; that is, one end of the resistor R3 is connected to the output terminal of the transformer, the other end of the resistor R3 is connected to the resistor R4, and the resistor R4 is grounded.
The resistor R2 is connected with the shunt reference source L1 in series, the resistor R2 is connected with the output end of the transformer, the anode of the shunt reference source L1 is grounded, and the reference electrode is connected with the resistor R3 and the resistor R4; that is, one end of the resistor R2 is connected to the output terminal of the transformer, the other end of the resistor R2 is connected to the anode (a terminal shown in the figure) of the light emitting diode included in the photocoupler, the anode of the shunt reference source L1 is grounded, the cathode is connected to the cathode (k terminal shown in the figure) of the light emitting diode included in the photocoupler, and the reference electrode is connected to both the resistor R3 and the resistor R4.
The above-mentioned optoelectronic coupling device of isolated feedback power supply includes: a light emitting diode and a light sensing triode.
The positive electrode and the negative electrode of the light emitting diode connected in series in the sampling circuit form the primary of the photoelectric coupling device, for example, the two ends a and k shown in the figure are the primary of the photoelectric coupling device.
The collector and the emitter of the phototriode form the secondary of the photoelectric coupling device, the collector of the phototriode is connected with the divider resistor R1, and the emitter is connected with the mirror current circuit. For example, the two ends c and e shown in the figure are secondary ends of the photoelectric coupling device.
The mirror current circuit of the isolated feedback power supply comprises: the base electrodes of the two NPN triodes are butted, the emitting electrodes of the two NPN triodes are grounded, wherein the collector electrode of one NPN triode is connected with the emitting electrode (shown as end e) of a photosensitive triode included in the photoelectric coupling device, and the collector electrode of the other NPN triode is connected with the adjusting circuit and the divider resistor R1. And a connecting wire is led out from the base electrode connecting wire of the two NPN triodes and is connected with a collector electrode leading-out wire of one of the NPN triodes. In fig. 5, the collector terminal of the NPN transistor connected to the photocoupler is taken as an example, and the collector terminal may be connected to the collector terminal of the NPN transistor connected to the resistor R1 in actual arrangement.
One end of the voltage dividing resistor R1 is connected with the FB pin of the power control chip in the adjusting circuit, the other end is connected with the photoelectric coupler (shown as a c end in the figure), and the end connected with the c end of the photoelectric coupler is applied with a voltage V2.
The above-mentioned regulating circuit of the isolated feedback power supply includes: power control chip and switch tube.
The power control chip is connected with the divider resistor R1 and the mirror current circuit and is used for adjusting the conduction duty ratio of the switching tube according to the pin voltage. Specifically, a feedback input end (FB pin) of the power control chip is connected with a divider resistor R1 and a collector of an NPN triode in the mirror current circuit.
The switch tube is connected with the power supply control chip and used for controlling the energy transferred from the input end to the output end of the transformer by changing the conduction duty ratio of the switch tube. The switch Q1 is shown with its gate connected to the power control chip, source grounded, and drain connected to the transformer input.
The principle of the isolated feedback power supply shown in fig. 4 and 5 for implementing isolated feedback control is shown in fig. 6, and the process of implementing feedback control by the isolated feedback power supply is as follows:
(1) voltage-current conversion
The sampling circuit samples the voltage at the output end of the transformer and converts the voltage into primary input current of the photoelectric coupling device.
The method specifically comprises the following steps: the voltage obtained by sampling the output end of the transformer is converted into the primary input current of the photoelectric coupling device by serially connecting the light emitting diode included in the photoelectric coupling device between the resistor R2 included in the sampling circuit and the shunt reference source L1.
(2) Current-photocurrent isolated conversion
Input current I of primary stageakGenerating a secondary output current I by a photoelectric couplerce。
Primary input current I of photoelectric coupling deviceakThe light emitted by the LED is sensed by the phototriode to generate an output current Ice。
(3) Mirror current circuit regulation
Maintaining input current I of primary side of photoelectric coupling device by mirror current circuit connected with secondary side of photoelectric coupling deviceakOutput current I to secondaryceAnd is linearly proportional.
Specifically, the linear proportional relation between the primary input current and the secondary output current of the photoelectric coupling device is maintained through the NPN triodes with two bases butted with each other.
Fig. 7 is a schematic diagram of the operating principle of the mirror current circuit, wherein T0 and T1 are NPN transistors with identical characteristics, and Ic and I are both obtained due to the symmetrical arrangement of the two NPN transistorsRTend to be equal, Ic and IRJust like aMirror and therefore become a mirror current circuit.
IakThe light generated by the light emitting diode is sensed by the phototriode to generate output current.
According to the principle, the current I flowing through the photoelectric coupling deviceceWith the current I flowing through the voltage-dividing resistorRThe voltages at the two ends of the photoelectric coupling devices c and e are constant and the current is variable due to the voltage V2 added at the other end of the voltage dividing resistor. Because the voltage is constant, the charging and discharging of the equivalent capacitance of the photoelectric coupling device are not needed. The current change on the photoelectric coupler is also fed back to the voltage-dividing resistor in a linear proportional relationship, so that the voltage input to the FB pin of the power supply control chip is also changed.
The improved isolated feedback power supply circuit can eliminate the difference of photoelectric coupling devices, so that the effect of the self-capacitance of the photoelectric coupling devices in a feedback loop is eliminated. Because the capacitance is the largest capacitive load in the feedback loop, the feedback bandwidth can be greatly improved after the capacitance is eliminated.
(4) Current-to-voltage conversion
And the output current of the secondary is converted into the pin voltage of the adjusting circuit connected with the mirror current circuit through the mirror current circuit and the divider resistor connected with the secondary of the photoelectric coupler.
(5) The voltage is output to a power supply control chip
The adjusting circuit adjusts the energy transmitted from the input end to the output end of the transformer according to the pin voltage. The method specifically comprises the following steps:
the adjusting circuit adjusts the conduction duty ratio of the switching tube according to the pin voltage.
And the switch tube controls the energy transferred from the input end to the output end of the transformer according to the adjusted conduction duty ratio.
According to the feedback control method of the isolated feedback power supply and the isolated feedback power supply provided by the embodiment of the invention, the secondary of the photoelectric coupling device is connected with the mirror current circuit, so that the voltages at the two ends of the photoelectric coupling devices c and e are approximately constant, the primary input current and the secondary output current of the photoelectric coupling device are in a linear proportional relationship, and the pin voltage of the adjusting circuit and the sampling voltage are in a linear proportional relationship. The isolated feedback power supply eliminates the influence of self-capacitance of a photoelectric coupling device on the bandwidth of the feedback circuit through the mirror current circuit, avoids the occurrence of a high-frequency filtering phenomenon, and improves the high-frequency gain of a feedback path. Therefore, the bandwidth of the feedback circuit is improved, the implementation cost is low, the reliability is high, and the high-frequency gain bandwidth can be effectively improved. Meanwhile, the purpose of improving the dynamic response of the feedback circuit is realized at lower cost, the requirement of the high-power switching power supply on the harsh load dynamic response can be met, and the high-power switching power supply which is used in special occasions and has higher load response requirement is manufactured.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (10)
1. An isolated feedback power supply comprising: transformer, sampling circuit, optoelectronic coupling device, adjusting circuit, its characterized in that still includes: a mirror current circuit and a voltage dividing resistor;
the sampling circuit is used for sampling the voltage at the output end of the transformer and converting the voltage into primary input current of the photoelectric coupling device;
the photoelectric coupling device is used for converting primary input current into secondary output current;
the voltage dividing resistor is connected with one end of the secondary of the photoelectric coupling device and the adjusting circuit and is used for converting the output current of the secondary of the photoelectric coupling device into the pin voltage of the adjusting circuit;
the mirror current circuit is connected with the other end of the secondary of the photoelectric coupling device and the adjusting circuit and is used for maintaining the linear proportional relation between the input current of the primary of the photoelectric coupling device and the output current of the secondary;
and one end of the adjusting circuit is connected with the mirror current circuit and the divider resistor, and the other end of the adjusting circuit is connected with the input end of the transformer and is used for adjusting the energy transferred from the input end to the output end of the transformer according to the pin voltage.
2. The isolated feedback power supply of claim 1, wherein said optocoupler includes: a light emitting diode and a light sensing triode;
the primary of the photoelectric coupling device comprises the anode and the cathode of a light emitting diode, and the light emitting diode is connected in series in the sampling circuit;
the secondary of the photoelectric coupler comprises a collector and an emitter of the phototriode; and the collector electrode of the photosensitive triode is connected with the divider resistor, and the emitter electrode of the photosensitive triode is connected with the mirror current circuit.
3. The isolated feedback power supply of claim 1 wherein said mirror current circuit comprises: two NPN triodes with butt-jointed bases;
the emitting electrodes of the two NPN triodes are grounded, wherein the collecting electrode of one NPN triode is connected with the emitting electrode of the photosensitive triode included in the photoelectric coupling device, and the collecting electrode of the other NPN triode is connected with the adjusting circuit and the divider resistor.
4. The isolated feedback power supply of claim 3, wherein the sampling circuit specifically comprises: a resistor (R2), a resistor (R3), a resistor (R4), and a shunt reference source;
one end of the resistor (R2) and one end of the resistor (R3) are connected with the output end of the transformer, the other end of the resistor (R2) is connected with the anode of a light-emitting diode included in the photoelectric coupling device, the other end of the resistor (R3) is connected with the resistor (R4), and the resistor (R4) is grounded;
the anode of the shunt reference source is grounded, the cathode of the shunt reference source is connected with the cathode of a light emitting diode included in the photoelectric coupling device, and the reference electrode of the shunt reference source is connected with the resistor (R3) and the resistor (R4).
5. An isolated feedback power supply as claimed in any of claims 1 to 4 wherein said regulation circuit comprises: a power supply control chip and a switching tube;
the power supply control chip is connected with the divider resistor and the mirror current circuit and is used for adjusting the conduction duty ratio of the switching tube according to the pin voltage;
the switch tube is connected with the power control chip and used for controlling the energy transferred from the input end to the output end of the transformer by changing the conduction duty ratio of the switch tube.
6. A method for feedback control of an isolated feedback power supply, comprising:
the sampling circuit samples the voltage at the output end of the transformer and converts the voltage into primary input current of a photoelectric coupling device;
the primary input current generates secondary output current through the photoelectric coupling device, and the linear proportional relation between the primary input current and the secondary output current of the photoelectric coupling device is maintained through a mirror current circuit connected with the secondary of the photoelectric coupling device;
converting the output current of the secondary to the pin voltage of an adjusting circuit connected with the mirror current circuit through a mirror current circuit and a divider resistor connected with the secondary of the photoelectric coupler;
and the adjusting circuit adjusts the energy transmitted from the input end to the output end of the transformer according to the pin voltage.
7. The method of claim 6, wherein said optocoupler includes: the light-emitting diode and the photosensitive triode are connected in series in the sampling circuit; wherein,
the primary of the photoelectric coupling device comprises the anode and the cathode of a light emitting diode; the secondary of the photoelectric coupler comprises a collector and an emitter of a phototriode, the collector of the phototriode is connected with the divider resistor, and the emitter is connected with the mirror current circuit;
the primary input current generates secondary output current through a photoelectric coupling device, and the method specifically comprises the following steps:
the input current generates light through the light emitting diode, and the light sensing triode senses the light generated by the light emitting diode to generate the output current.
8. The method of claim 7, wherein the mirror current circuit comprises: two NPN triodes with butt-jointed bases; the emitting electrodes of the two NPN triodes are grounded, wherein the collector electrode of one NPN triode is connected with the emitting electrode of the photosensitive triode included in the photoelectric coupler, and the collector electrode of the other NPN triode is connected with the adjusting circuit and the divider resistor;
and maintaining the linear proportional relation between the primary input current and the secondary output current of the photoelectric coupling device through the two NPN triodes.
9. The method of claim 7, wherein the sampling circuit specifically comprises: a resistor (R2), a resistor (R3), a resistor (R4), and a shunt reference source; the resistor (R3) is connected with the resistor (R4) in series, the resistor (R3) is connected with the output end of the transformer, and the resistor (R4) is grounded; the resistor (R2) is connected with a shunt reference source in series, the resistor (R2) is connected with the output end of the transformer, the anode of the shunt reference source is grounded, and a reference pole is connected with the resistor (R3) and the resistor (R4);
sampling circuit samples the voltage of transformer output to convert the elementary input current of photoelectric coupling device, specifically include:
the voltage obtained by sampling the output end of the transformer is converted into the primary input current of the photoelectric coupling device by connecting a light emitting diode included in the photoelectric coupling device between a resistor (R2) included in the sampling circuit and a shunt reference source in series; the anode of the light emitting diode is connected with the resistor (R2), and the cathode of the light emitting diode is connected with the cathode of the shunt reference source.
10. The method according to any of claims 6-9, wherein the adjusting circuit specifically comprises: a power supply control chip and a switching tube; the power supply control chip is connected with the divider resistor and the mirror current circuit, and the switching tube is connected with the power supply control chip;
the adjusting circuit adjusts the magnitude of energy transferred from the input end to the output end of the transformer according to the pin voltage, and specifically comprises:
the adjusting circuit adjusts the conduction duty ratio of the switching tube according to the pin voltage;
and the switch tube controls the energy transferred from the input end to the output end of the transformer according to the adjusted conduction duty ratio.
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| CN109167534A (en) * | 2018-09-26 | 2019-01-08 | 上海雷诺尔科技股份有限公司 | A kind of mesohigh solid state motor soft starter high-frequency isolation power supply circuit |
| CN110824221A (en) * | 2019-11-15 | 2020-02-21 | 天宝电子（惠州）有限公司 | A DC Voltage Isolated Sampling Circuit |
| CN113799604A (en) * | 2021-10-21 | 2021-12-17 | 浙江致威电子科技有限公司 | Sampling power supply system |
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| CN2613940Y (en) * | 2003-02-25 | 2004-04-28 | 武汉精伦电子股份有限公司 | Power source module for user's circuit of U interface of ISDN |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104242698A (en) * | 2014-10-18 | 2014-12-24 | 许昌学院 | Dual output switching power supply for helium-neon laser |
| CN106559066A (en) * | 2016-09-13 | 2017-04-05 | 北京博纳电气股份有限公司 | The circuit of optocoupler response speed is lifted based on mirror current source |
| CN109167534A (en) * | 2018-09-26 | 2019-01-08 | 上海雷诺尔科技股份有限公司 | A kind of mesohigh solid state motor soft starter high-frequency isolation power supply circuit |
| CN110824221A (en) * | 2019-11-15 | 2020-02-21 | 天宝电子（惠州）有限公司 | A DC Voltage Isolated Sampling Circuit |
| CN113799604A (en) * | 2021-10-21 | 2021-12-17 | 浙江致威电子科技有限公司 | Sampling power supply system |
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Application publication date: 20100811 |