CN108832667B - Soft start control circuit applied to control of DC output of switching power supply - Google Patents
Soft start control circuit applied to control of DC output of switching power supply Download PDFInfo
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- CN108832667B CN108832667B CN201810416087.9A CN201810416087A CN108832667B CN 108832667 B CN108832667 B CN 108832667B CN 201810416087 A CN201810416087 A CN 201810416087A CN 108832667 B CN108832667 B CN 108832667B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/36—Means for starting or stopping converters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
- H02M1/34—Snubber circuits
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- Continuous-Control Power Sources That Use Transistors (AREA)
Abstract
The invention relates to a soft start control circuit applied to controlling the direct current output of a switching power supply, which comprises a control switching tube module and a linear optocoupler module, wherein the control switching tube module is connected with a power supply; the input end of the control switch tube module is used for being connected with a switch power supply direct current output starting signal, the output end of the control switch tube module is connected with a primary side loop of the linear optocoupler module, and a secondary side loop of the linear optocoupler module is used for being connected with a control circuit of the switch power supply direct current output. When a direct current output starting signal of the switching power supply is received, the switching tube module is controlled to be in a linear amplification state, the voltage of a secondary side loop of the linear optical coupling module slowly changes, and the secondary side of the linear optical coupling module is directly connected to the output control end of the switching power supply, so that the given value of the output voltage of the direct current switching power supply smoothly climbs to the final given value, and the phenomenon of output overshoot caused by slow speed of a closed-loop regulation loop and overhigh voltage of an initial output given control pin is effectively avoided when the direct current switching power supply is started.
Description
Technical Field
The invention relates to a soft start control circuit applied to controlling the direct current output of a switching power supply, and belongs to the technical field of electronic circuits.
Background
When the existing partial direct current switch power supply device is started under load, when an output closed loop regulating circuit is powered before the output of the switch power supply and the closed loop regulating speed is slow, large voltage and current overshoot is easily caused, and certain damage is caused to the direct current switch power supply. Therefore, how to effectively avoid overvoltage or overcurrent when the dc switching power supply device is started in an on-load mode is of great significance to protection of the dc switching power supply device.
Disclosure of Invention
The invention aims to provide a soft start control circuit applied to control of direct current output of a switching power supply, which is used for solving the problem of output overshoot of a direct current switching power supply device during on-load starting.
In order to solve the technical problem, the invention provides a soft start control circuit applied to control the direct current output of a switching power supply, which comprises a control switching tube module and a linear optocoupler module; the input end of the control switch tube module is used for connecting a switch power supply direct current output starting signal, and the output end of the control switch tube module is connected with a primary side loop of the linear optocoupler module and used for: when a switching power supply direct current output starting signal is not received, the switching tube module is controlled to charge, and when the switching power supply direct current output starting signal is received, the switching tube module is controlled to discharge so as to provide gradually reduced current for a primary side loop of the linear optocoupler module; and a secondary side loop of the linear optocoupler module is used for connecting a control circuit of the direct current output of the switching power supply.
The invention has the beneficial effects that: when a switching power supply direct current output starting signal exists, the switching tube module is controlled to be in a linear amplification state, the secondary side loop voltage of the linear optical coupling module slowly changes at the moment, the secondary side of the linear optical coupling module is directly connected to the switching power supply output control end, so that the given value of the direct current switching power supply output voltage slowly climbs to the final given value, the effect that the switching power supply output control end slowly changes is achieved, and the phenomenon that output overshoot is caused by the fact that the speed of a closed-loop regulation loop is slow and the voltage of a given control pin is excessively high during initial output when the direct current switching power supply is started is effectively avoided.
Furthermore, in order to realize the control of the output soft start time of the direct current switch power supply, the control switch tube module is connected with the direct current output start signal of the switch power supply through a timing module and is used for charging the control switch tube module after the direct current output start signal of the switch power supply is received and the time delay is set.
Furthermore, in order to control the control switch tube module to be in a linear amplification state after a set time delay after receiving a starting signal, the control switch tube module comprises a first triode, a base of the first triode is connected with the timing module, a grounding capacitor is further connected between the timing module and the base of the first triode, a collector of the first triode is connected with a primary side loop of the linear optocoupler module, and an emitter of the first triode is grounded.
Further, in order to control the current of the control switch tube module in the charging and discharging process, resistors are connected in series between the timing module and the base of the first triode and between the base of the first triode and the ground.
Further, in order to realize a timing function, the timing module comprises a second triode and a double-D trigger; the base electrode of the second triode is used for being connected with a direct-current output starting signal of a switching power supply, the collector electrode of the second triode is connected with a first wiring end of a first resistance-capacitance charging and discharging module, a second wiring end of the first resistance-capacitance charging and discharging module is connected with a reset wiring end of the double-D trigger, and the emitter electrode of the second triode is grounded; the base electrode of the second triode is further connected with a first wiring end of a second resistance-capacitance charging and discharging module, and a second wiring end of the second resistance-capacitance charging and discharging module is connected with a set wiring end of the double-D trigger.
Furthermore, in order to realize the control of the timing module, the resistance-capacitance charge-discharge module comprises a first resistor, a second resistor and a charge-discharge capacitor, the first resistor is serially arranged between a first terminal and a second terminal of the resistance-capacitance charge-discharge module, the second resistor is connected with the charge-discharge capacitor in parallel, one parallel point of the second resistor and the charge-discharge capacitor is grounded, and the other parallel point is connected with the second terminal of the resistance-capacitance charge-discharge module.
Drawings
FIG. 1 is a schematic diagram of a soft start control circuit for controlling the DC output of a switching power supply;
fig. 2 is a circuit diagram of a soft start control circuit applied to control the dc output of a switching power supply.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
The invention provides a soft start control circuit for controlling the direct current output of a switching power supply, which has a structural schematic diagram shown in figure 1 and comprises a switch power supply direct current output initial given voltage control pin starting time timing circuit, an output linear circuit formed by an optical coupler and a switch power supply direct current output closed loop regulating circuit. The input end of the switch power supply direct current output initial given voltage control pin starting time timing circuit is used for receiving a switch power supply direct current output starting signal, the output end of the switch power supply direct current output initial given voltage control pin starting time timing circuit is connected with the input end of an output linear circuit formed by an optical coupler, and the output end of the output linear circuit formed by the optical coupler is connected with a switch power supply direct current output control end and a switch power supply direct current output closed-loop regulating circuit.
The switching power supply direct current output starting signal is a switching power supply output enabling signal, and when the switching power supply receives the signal, the output side of the switching power supply starts to output.
As shown in fig. 2, the switching power supply dc output initial given voltage control pin start time timing circuit (timing module) includes a second triode Q1 and a dual-D flip-flop U1A, a base of the second triode Q1 is connected to a switching power supply dc output start signal through a resistor R1, a collector of the second triode Q1 is connected to a first terminal of a first rc charge-discharge module, and a second terminal of the first rc charge-discharge module is connected to a reset terminal R of the dual-D flip-flop. The base electrode of the second triode Q1 is connected with the first terminal of a second resistance-capacitance charge-discharge module through a resistor R1, and the second terminal of the second resistance-capacitance charge-discharge module is connected with the set terminal S of the double-D trigger. And the output end Q of the double-D trigger is used as the output end of the whole timing module and is used for being connected with the input end of an output linear circuit formed by the optocouplers.
For each resistance-capacitance charge-discharge module, each resistance-capacitance charge-discharge module comprises a first resistor, a second resistor, a charge-discharge capacitor, a first wiring terminal and a second wiring terminal, the first resistor is serially arranged between the first wiring terminal and the second wiring terminal of the resistance-capacitance charge-discharge module, the second resistor is connected with the charge-discharge capacitor in parallel, one parallel point of the second resistor and the charge-discharge capacitor is grounded, and the other parallel point of the second resistor and the charge-discharge capacitor is connected with the second wiring terminal of the resistance-capacitance charge-discharge module.
In this embodiment, the type of the dual D flip-flop is CD4013, but as another embodiment, in the case that the timing requirement is satisfied, the dual D flip-flop of another type may also be used.
The output linear circuit formed by the optical couplers comprises a control switch tube module and a linear optical coupler module, wherein the input end of the control switch tube module is connected with the output end of the timing module, the output end of the control switch tube module is connected with a primary side loop of the linear optical coupler module, and a secondary side loop of the linear optical coupler module is used for being connected with a control circuit of the direct current output of the switching power supply.
As shown in fig. 2, the control switch module includes a first transistor Q2, a base of the first transistor Q2 is connected to the timing module, a grounded capacitor C3 is further connected between the timing module and the base of the first transistor Q2, a collector of the first transistor Q2 is connected to a primary loop of the linear optocoupler module, and an emitter of the first transistor Q2 is grounded. In order to achieve charge and discharge control of the ground capacitor C3, a resistor R9 is connected in series between the base of the first transistor Q2 and the timing block, and a resistor R10 is connected in series between the base of the first transistor Q2 and ground.
The linear optocoupler module is composed of a linear optocoupler O1, a primary side loop of the linear optocoupler O1 is connected with the output end of the control switch tube module, one wiring terminal in a secondary side loop of the linear optocoupler O1 is grounded, the other wiring terminal is used for being connected with a direct current output control end of the switch power supply and is connected with a direct current closed-loop regulation output end of the switch power supply through a resistor R12, and the direct current closed-loop regulation output end of the switch power supply is connected with a direct current output closed-loop regulation circuit of the switch power supply.
When the switching power supply receives a direct current output starting signal, the direct current closed-loop regulating output end of the switching power supply is pulled down by a linear optical coupler secondary side connected with the output control end of the switching power supply, the direct current output low voltage of the switching power supply is slowly raised until the voltage of the linear optical coupler secondary side is raised to the output closed-loop regulating voltage of the switching power supply after the starting timing time, and the switching process from a soft starting circuit to a closed-loop regulating circuit is completed.
The soft start control circuit applied to control the direct current output of the switching power supply has the following working principle: when the timing module does not receive the starting signal of the direct current output side of the switching power supply, namely the direct current output of the switching power supply is not started, the direct current output starting signal of the switching power supply is at a high level. At this time, a reset terminal R of the dual D flip-flop U1A is connected to a low level, a set terminal S of the dual D flip-flop is connected to a high level, an output terminal Q of a timing module formed by the triode Q1 and the dual D flip-flop U1A is at a high level, and a voltage of a direct current output control terminal of the switching power supply is pulled down by an output linear circuit formed by the opto-couplers.
When the timing module receives a starting signal of the direct current output side of the switching power supply, namely the direct current output of the switching power supply is started, the direct current output starting signal of the switching power supply is at a low level. At this time, the power source VCC charges the capacitor C1 through the resistors R3 and R4, the capacitor C2 discharges through the resistor R7, the low level connected to the reset terminal R of the dual D flip-flop U1A changes to the high level, the high level connected to the set terminal S of the dual D flip-flop changes to the low level, and the output terminal Q of the dual D flip-flop changes from the high level to the low level. By adjusting the parameter values of R3, R4, R5 and C1 and the parameter values of resistor R7 and capacitor C2, the time at which the 1-pin of U1A flips from high to low can be determined. Through setting up this timing module, can set for the back of start time, output required level signal gives the opto-coupler and constitutes output linear circuit to open this output linear circuit.
After the output end Q of the timing module is changed into a low level, the collector current of the triode Q2 in an amplifying state is gradually reduced in the continuous discharging process of the capacitor C3, the primary side current of the optical coupler is adjusted, and the secondary side voltage of the optical coupler is changed slowly. Because R8, R9, R10, R11, R12, Q2 and O1 constitute an output linear circuit, the ideal level value can be output by the O1 secondary side of the optical coupler by adjusting the parameter values of C3, R9, R11 and R12, and therefore the purpose of gentle conversion of the O1 secondary side level is achieved when the level is switched between R8 and U1A. Because the secondary side of the optical coupler O1 is directly connected to the output control end of the switching power supply and is connected with the direct-current closed-loop regulating output end of the switching power supply through the resistor R12, when the clamping level of the secondary side of the O1 is higher than the output signal of the output closed-loop regulating circuit of the switching power supply, the signal of the direct-current output control end of the switching power supply is switched to the output level signal of the output closed-loop regulating circuit of the switching power supply, and the control voltage of the direct-current output control end of the switching power supply slowly rises exponentially until the. The switch power supply direct current output closed loop regulating circuit outputs the output detection signal and the output given signal to the voltage required by the control end of the switch power supply through a PID (proportional integral derivative) circuit, so that the output signal is output to the given value, and finally the switch power supply direct current output soft start is finished. Since the specific structure of the dc output closed-loop regulating circuit of the switching power supply belongs to the prior art, it is not described herein again.
The soft start control circuit applied to control the direct current output of the switching power supply sets the soft start time of the output of the direct current switching power supply, the initial set value size of the output control pin of the switching power supply and the climbing rate of the initial set value of the output control pin through the output start signal of the direct current switching power supply, enables the set value of the output voltage to slowly climb to the final set value of the direct current switching power supply, avoids output overshoot caused by low closed loop regulation loop speed and overhigh voltage of the initial output set control pin when the direct current switching power supply is started, effectively solves the problem of output load overshoot when the power supply is initially electrified, and avoids damage to the direct current switching power supply caused by the output overshoot.
In addition, it should be noted that the soft start control circuit of the present invention may also be configured without a timing module, and directly access the start signal of the dc output side of the switching power supply to the optical coupler composed of the control switch tube module and the linear optical coupler module to form an output linear circuit.
The above description is only for assisting understanding of the method and core idea of the present invention, and various modifications and parameter modifications designed by the person skilled in the art according to the teaching of the present invention still fall within the protection scope of the present invention.
Claims (4)
1. A soft start control circuit applied to control the direct current output of a switching power supply is characterized by comprising a control switching tube module and a linear optocoupler module; the input end of the control switch tube module is used for connecting a switch power supply direct current output starting signal, and the output end of the control switch tube module is connected with a primary side loop of the linear optocoupler module and used for: when a switching power supply direct current output starting signal is not received, the switching tube module is controlled to charge, and when the switching power supply direct current output starting signal is received, the switching tube module is controlled to discharge so as to provide gradually reduced current for a primary side loop of the linear optocoupler module; one wiring terminal of a secondary side loop of the linear optocoupler module is used for being simultaneously connected with the output end of the switching power supply direct current output closed-loop regulating circuit and the output end of the switching power supply direct current output control end;
when the secondary side clamping level of the linear optocoupler module is higher than the output level of the switching power supply direct current output closed-loop regulating circuit, the level signal of the switching power supply direct current output control end is switched to the output level signal of the switching power supply direct current output closed-loop regulating circuit, so that the control voltage of the switching power supply direct current output control end slowly rises exponentially until the given voltage is regulated in a closed loop; the switch power supply direct current output closed loop regulating circuit outputs the voltage required by the control end of the switch power supply through the PID circuit by outputting the output detection signal and the output given signal;
the control switch tube module is connected with a switch power supply direct current output starting signal through a timing module and is used for charging the control switch tube module after a set time delay after receiving the switch power supply direct current output starting signal;
the timing module comprises a second triode and a double-D trigger; the base electrode of the second triode is used for being connected with a direct-current output starting signal of a switching power supply, the collector electrode of the second triode is connected with a first wiring end of a first resistance-capacitance charging and discharging module, a second wiring end of the first resistance-capacitance charging and discharging module is connected with a reset wiring end of the double-D trigger, and the emitter electrode of the second triode is grounded; the base electrode of the second triode is further connected with a first wiring end of a second resistance-capacitance charging and discharging module, and a second wiring end of the second resistance-capacitance charging and discharging module is connected with a set wiring end of the double-D trigger.
2. The soft-start control circuit for controlling a dc output of a switching power supply as claimed in claim 1, wherein the control switch module comprises a first transistor, a base of the first transistor is connected to the timing module, a ground capacitor is connected between the timing module and the base of the first transistor, a collector of the first transistor is connected to the primary side loop of the linear optocoupler module, and an emitter of the first transistor is grounded.
3. The soft-start control circuit for controlling the dc output of a switching power supply as claimed in claim 2, wherein a resistor is connected in series between the timing module and the base of the first transistor and between the base of the first transistor and ground.
4. The soft-start control circuit applied to control of the direct-current output of the switching power supply of claim 1, wherein the resistance-capacitance charging and discharging module comprises a first resistor, a second resistor and a charging and discharging capacitor, the first resistor is serially arranged between a first terminal and a second terminal of the resistance-capacitance charging and discharging module, the second resistor is connected with the charging and discharging capacitor in parallel, one parallel point of the second resistor and the charging and discharging capacitor is grounded, and the other parallel point is connected with the second terminal of the resistance-capacitance charging and discharging module.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810416087.9A CN108832667B (en) | 2018-05-03 | 2018-05-03 | Soft start control circuit applied to control of DC output of switching power supply |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810416087.9A CN108832667B (en) | 2018-05-03 | 2018-05-03 | Soft start control circuit applied to control of DC output of switching power supply |
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| Publication Number | Publication Date |
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| CN108832667A CN108832667A (en) | 2018-11-16 |
| CN108832667B true CN108832667B (en) | 2020-09-25 |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101154881A (en) * | 2006-09-29 | 2008-04-02 | 群康科技(深圳)有限公司 | Switch power circuit |
| CN103427618A (en) * | 2013-06-24 | 2013-12-04 | 深圳市英威腾电气股份有限公司 | Soft start control circuit |
| CN204598412U (en) * | 2015-05-13 | 2015-08-26 | 深圳市垅运照明电器有限公司 | A kind of LED drive power soft starting circuit |
| CN105262326A (en) * | 2015-11-16 | 2016-01-20 | 中国电子科技集团公司第四十三研究所 | Starting control circuit for output linear voltage of switching power supply |
| CN106487210A (en) * | 2015-08-26 | 2017-03-08 | 山东华网智能科技股份有限公司 | A kind of soft start/soft pass closed circuit being applied to DC/DC Switching Power Supply |
-
2018
- 2018-05-03 CN CN201810416087.9A patent/CN108832667B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101154881A (en) * | 2006-09-29 | 2008-04-02 | 群康科技(深圳)有限公司 | Switch power circuit |
| CN103427618A (en) * | 2013-06-24 | 2013-12-04 | 深圳市英威腾电气股份有限公司 | Soft start control circuit |
| CN204598412U (en) * | 2015-05-13 | 2015-08-26 | 深圳市垅运照明电器有限公司 | A kind of LED drive power soft starting circuit |
| CN106487210A (en) * | 2015-08-26 | 2017-03-08 | 山东华网智能科技股份有限公司 | A kind of soft start/soft pass closed circuit being applied to DC/DC Switching Power Supply |
| CN105262326A (en) * | 2015-11-16 | 2016-01-20 | 中国电子科技集团公司第四十三研究所 | Starting control circuit for output linear voltage of switching power supply |
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