CN111725985A - Soft start control circuit applied to electric power product - Google Patents
Soft start control circuit applied to electric power product Download PDFInfo
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- CN111725985A CN111725985A CN202010665527.1A CN202010665527A CN111725985A CN 111725985 A CN111725985 A CN 111725985A CN 202010665527 A CN202010665527 A CN 202010665527A CN 111725985 A CN111725985 A CN 111725985A
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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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Abstract
The patent discloses a be applied to soft start control circuit of electric power product, including power module, IC chip and soft module of opening, wherein the soft module of opening includes that first soft module, the soft module of opening of second, and first soft module of opening links to each other with IC chip current comparator pin, and the soft module of opening of second links to each other with power module's feedback sampling voltage. Through the cooperation of the peripheral circuit and the internal circuit of the switch power supply IC chip, the output duty ratio of the power supply is slowly expanded when the power supply is just started, and the phenomenon that the switch is turned on due to overlong time and burnout due to overheating caused by the output of PWM (pulse width modulation) pulse with large duty ratio is prevented. Meanwhile, the circuit solves the problem that the parameter setting and the system performance are difficult to balance in the traditional soft start control technology, and the circuit can still keep the soft start function under the extreme condition of quick startup and shutdown, so that the reliability and the stability of the system are greatly improved.
Description
Technical Field
The invention relates to the field of power supplies, in particular to a soft start control circuit applied to an electric power product.
Background
Integrated IC chips have been widely used in switching power supplies in recent years due to their numerous advantages. However, when the power supply is just switched on, the voltage stabilizing circuit does not enter a working state, and a certain time is required for establishing the output voltage of the switching power supply, so that the chip is in an open-loop working state in the period of time, the chip outputs a PWM pulse with a large duty ratio, and the switch is switched on for too long time, so that the switch is easily burnt out due to overheating.
In order to protect the power product from surge impact during startup, soft start control is usually implemented by combining an off-chip circuit and an on-chip circuit. In the existing soft start control technology, parameter setting is difficult, if the charging starting time is too long, intermittent working of the switching power supply is easy to occur, and meanwhile, when the soft start is finished and a normal working mode is entered, the loop response speed is slowed down, so that the overall performance of a product is reduced; if the starting charging time is designed to be too short, the soft starting control is lost, and the surge impact risk still exists. In addition, the power grid environment is complex and changeable, the extreme condition of quick startup and shutdown exists, and the soft start control circuit of the existing power product basically loses the function of soft start at the moment.
Disclosure of Invention
In order to solve the above problems, the present invention provides a soft start control circuit applied to an electric power product, and the technical scheme of the present invention is as follows:
the invention provides a soft start control circuit applied to an electric power product, which comprises a power supply module, an IC chip and a soft start module, wherein the soft start module comprises a first soft start module and a second soft start module, the first soft start module is connected with a pin of a current comparator of the IC chip, and the second soft start module is connected with a feedback sampling voltage of the power supply module.
Further, the first soft start module comprises a first resistor and a first capacitor, a first end of the first resistor is connected with the loop compensation pin of the IC chip, a second end of the first resistor is connected with a first end of the first capacitor, and a second end of the first capacitor is grounded; the second soft start module comprises: the circuit comprises an anti-reflection diode, a PNP type triode, a second resistor, a second capacitor and a third resistor; the emitter e of the P-type triode is connected with the first end of the first resistor, and the base b of the P-type triode is connected with the first end of the second resistor, the first end of the second capacitor, the second end of the third resistor and the anode of the anti-reverse diode; the collector c of the P-type triode is grounded, and the second end of the second resistor and the second end of the second capacitor are grounded; the first end of the third resistor and the cathode of the anti-reverse diode are connected with the feedback sampling voltage of the power supply module.
Further, the first resistor of the first soft start module is used for adjusting an initial reference voltage for soft start charging of the IC chip, wherein the initial reference voltage is a pin voltage connected with the first soft start module when the chip starts to work; the first capacitor and the first resistor jointly adjust the charging time of the first soft start module.
Further, the second capacitor and the third resistor jointly adjust the charging time of the second soft start module after the voltage feedback loop is established; the second capacitor and the second resistor jointly adjust the power-down time of the second soft start module during power-down; the second resistor and the third resistor are set to reasonably divide voltage to prevent the triode from being triggered by mistake; the anti-reverse diode prevents the current from flowing backward.
Further, when the voltage difference between the first soft start module and the second soft start module reaches the starting voltage, the PNP type triode is conducted and shunted, and the charging current of the first soft start module is reduced.
The soft start module charges a power pin of the IC chip through the startup charging circuit when the power supply is just switched on; when the charging voltage of a power supply pin reaches the working voltage of the chip, the chip starts to work, the establishment of the output voltage of the system needs a certain time, if no soft start circuit exists, the lower output voltage enables the voltage of the input end of the error comparator added in the IC chip to be very high, and the chip outputs PWM pulse with a very large duty ratio in the time; due to the existence of the soft start module, when the computer is just started, the voltage of the first capacitor is 0, so that the voltage applied to the < - > input end is also 0, and the chip outputs a low level; as the first soft start module continues to charge, the voltage applied to the "-" input gradually increases and the chip sends out PWM pulses with a smaller duty cycle.
Further, when the charging voltage of the first soft start module is greater than the voltage of the second capacitor, namely the PNP type triode be reaches a starting voltage, the triode is conducted and shunted, at the moment, the charging current of the first soft start module is very small, the charging voltage is slowly increased, and the duty ratio is continuously and slowly expanded until the power supply enters a stable working state.
Further, after the power supply system establishes a stable working state, the stable voltage of the feedback circuit is sampled to charge the second capacitor, when the voltage of the feedback circuit is higher than the voltage of the first soft start module, namely the triode is cut off, the first soft start module and the second soft start module are mutually disconnected, at the moment, the circuit enters a normal working mode, and the soft start is finished.
Preferably, the second soft start module limits the charging current of the first soft start module, and the second soft start module automatically breaks away during normal operation, so that the overall loop compensation of the system is not affected, and the parameter setting of the first soft start module is mainly based on the high performance of the circuit during normal operation.
Further, when the power supply is powered off, the second capacitor is rapidly discharged to zero through the second resistor, and the first soft start module mainly with high performance is discharged more rapidly, so that the soft start module can be rapidly discharged to zero. When the power is turned on or off rapidly, the soft start module can still work normally, and the traditional soft start circuit cannot discharge to zero rapidly due to power failure, so that the soft start function is lost when the power is turned on or off rapidly.
The invention has the beneficial effects that: the utility model provides a neotype soft start control circuit, can overcome traditional soft start circuit parameter setting comparatively difficult, be difficult to the problem of reasonable control start-up charge time, overcome soft start simultaneously and ended entering normal during operation, loop response speed slows down, leads to the problem that the product wholeness can descend to, under the extreme condition of quick switch machine, still can keep the effect of soft start, improved the security and the reliability of system.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the technical solutions in the prior art will be briefly described below, and it is obvious that the drawings are an embodiment of the present invention, and those skilled in the art can also obtain other drawings according to the principle of the drawings without creative efforts.
FIG. 1 is a functional block diagram of the present invention;
FIG. 2 is a schematic diagram of a soft start circuit according to an embodiment of the present invention;
description of reference numerals: r1 is a first resistor; r2 is a second resistor; r3 is a third resistor; d1 is an anti-reverse diode; PGND is transformer primary ground; DGND is transformer secondary ground; c1 is a first capacitor; c2 is a second capacitor; VT1 is P-type triode; TL is the sampling voltage of the feedback circuit; VDAC is the input DC voltage of the power supply system; OUT is a chip PWM output pin; CS is a current detection pin; FB is a voltage feedback pin; COM is a loop compensation pin; VCC is a chip power supply pin; and the RT/CT sets pins for the working frequency of the chip.
Detailed Description
In order to explain technical contents, achieved objects, and effects of the present invention in detail, the following description is made with reference to the accompanying drawings in combination with the embodiments.
As shown in fig. 1, a soft start control circuit applied to an electric power product includes a power module, an IC chip, and a soft start module.
As shown in fig. 2, in a soft start control circuit applied to an electric power product, a power supply module is a typical primary feedback flyback DC-DC converter, an IC chip is a mainstream switching power supply chip in the market, and a soft start module includes a first soft start module and a second soft start module; the first soft start module is connected with a pin of the IC chip current comparator, and the second soft start module is connected with the feedback sampling voltage of the power supply module. Obviously, this is an embodiment of the present invention, and the power topology can be adjusted according to its actual requirements, and the parameters can be adjusted according to the principle of the attached drawings to meet different designs and requirements.
The power module described in this embodiment is a primary-side feedback flyback DC-DC converter, and the auxiliary power supply winding is configured to provide a continuous and stable power supply for the IC chip when the auxiliary power supply winding normally works, and simultaneously sample the voltage of the winding and feed back the voltage to the FB pin of the chip, thereby adjusting and controlling the duty ratio of PWM, and after the start-up is completed to establish a stable working state, the power module provides a charging power supply for the second soft start-up module, disconnects the two-stage soft start-up modules, and ensures that the second soft start-up module does not affect the loop performance of the entire system.
The IC chip is a mainstream switching power supply chip in the current market, and the soft start function is jointly completed by building a peripheral circuit to be matched with the IC chip;
the first end of the first resistor R1 and the emitter e of the P-type triode VT1 are connected with a COM pin of the chip, the I-input end of an error comparator in the IC chip is connected through the internal structure of the chip, the second end of the first resistor R1 is connected with the first end of a first capacitor C1, and the second end of the first capacitor C1 is grounded; the base electrode b of the P-type triode VT1 is connected with the first end of the second resistor R2, the first end of the second capacitor C2, the second end of the third resistor R3 and the anode of the anti-reflection diode D1; the collector C of the P-type triode VT1 is grounded, the second end of the second resistor R2 and the second end of the second capacitor C2 are grounded; the first end of the third resistor R3 and the cathode of the anti-reverse diode are connected to the sampled voltage of the feedback circuit.
When a power supply is just switched on, the VCC is charged through a starting charging circuit, when the VCC reaches a chip starting voltage, the chip starts to work, at the moment, the output voltage of a system is not established, the FB pin is 0, the error amplifier outputs the maximum value, and the chip outputs PWM pulses with large duty ratio at the time; however, due to the presence of the first soft-start block, upon start-up, the voltage of the first capacitor C1 is 0, and then the charging of C1 through the first resistor R1 is started, the voltage applied to the "-" input of the error comparator gradually increases, and the chip sends out PWM pulses with a smaller duty cycle.
Further, the first resistor R1 is used for adjusting the initial reference voltage for the soft start charging of the IC chip, and the first capacitor C1 and the first resistor R1 together adjust the charging time of the first soft start module.
Further, as the voltage of the first capacitor C1 increases, when the voltage difference between the first capacitor C1 and the second soft start module reaches the turn-on voltage, i.e. the P-type triode VT1 is turned on, most of the current is shunted by the VT1, the charging current of the first soft start module decreases, the COM pin voltage continues to rise slowly, and the PWM duty cycle is spread slowly until a voltage feedback loop is established.
Further, after the system voltage feedback loop is established, the sampling feedback voltage charges a second capacitor C2 through a third resistor R3, then the second capacitor C2 gradually rises, when the voltage is higher than the COM voltage, namely the base voltage of a P-type triode VT1 is larger than the emitter voltage, the triode is cut off, the soft start is finished, the system enters a normal working mode, and the second soft start module and the system loop feedback are disconnected, so that the working performance of the system is not influenced.
In a further embodiment, the charging time of the second soft start module is regulated by the second capacitor C2 in conjunction with the third resistor R3.
When the power supply is powered off, the second capacitor C2 discharges quickly to zero through the second resistor R2 while the first soft start high performance module discharges more quickly, and thus the soft start module can discharge quickly to zero. When the power is turned on or off rapidly, the soft start module can still work normally, and the traditional soft start circuit cannot discharge to zero rapidly due to power failure, so that the soft start function is lost when the power is turned on or off rapidly.
Further, after the P-type transistor VT1 is turned off, the voltage divided by the second resistor R2 should be greater than the COM pin voltage, so as to prevent the transistor from being triggered by mistake.
Preferably, the second soft start module limits the charging current of the first soft start module, and the second soft start module automatically breaks away during normal operation, so that the overall loop compensation of the system is not affected, and the parameter setting of the first soft start module is mainly based on the high performance of the circuit during normal operation.
The invention provides a soft start control circuit applied to an electric power product, which enables the parameter setting to be simpler and more convenient, can still ensure the high performance of the system during normal work, and still keeps the soft start function under the extreme condition of quick startup and shutdown.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent changes made by using the contents of the present specification and the drawings, or applied directly or indirectly to the related technical fields, are included in the scope of the present invention.
Claims (4)
1. The utility model provides a be applied to soft start control circuit of electric power product which characterized in that, includes power module, IC chip and soft module of opening, and wherein the soft module of opening includes first soft module of opening, the soft module of opening of second, and first soft module of opening links to each other with IC chip current comparator pin, and the soft module of opening of second links to each other with power module's feedback sampling voltage.
2. The soft-start control circuit applied to the power product as claimed in claim 1, wherein the first soft-start module comprises a first resistor and a first capacitor, a first end of the first resistor is connected to the loop compensation pin of the IC chip, a second end of the first resistor is connected to a first end of the first capacitor, and a second end of the first capacitor is grounded; the second soft start module comprises: the circuit comprises an anti-reflection diode, a PNP type triode, a second resistor, a second capacitor and a third resistor; the emitter e of the P-type triode is connected with the first end of the first resistor, and the base b of the P-type triode is connected with the first end of the second resistor, the first end of the second capacitor, the second end of the third resistor and the anode of the anti-reverse diode; the collector c of the P-type triode is grounded, and the second end of the second resistor and the second end of the second capacitor are grounded; the first end of the third resistor and the cathode of the anti-reverse diode are connected with the feedback sampling voltage of the power supply module.
3. The soft-start control circuit applied to the electric power product as claimed in claim 2, wherein the first soft-start module first resistor is used for adjusting an initial reference voltage for soft-start charging of the IC chip, and the initial reference voltage is a pin voltage connected with the first soft-start module when the chip starts to operate; the first capacitor and the first resistor jointly adjust the charging time of the first soft start module.
4. The soft-start control circuit applied to the electric power product of claim 2, wherein the second capacitor and the third resistor together regulate the charging time of the second soft-start module after the voltage feedback loop is established; the second capacitor and the second resistor jointly adjust the power-down time of the second soft start module during power-down; the second resistor and the third resistor are set to reasonably divide voltage to prevent the triode from being triggered by mistake; the anti-reverse diode prevents the current from flowing backward.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010665527.1A CN111725985A (en) | 2020-07-11 | 2020-07-11 | Soft start control circuit applied to electric power product |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010665527.1A CN111725985A (en) | 2020-07-11 | 2020-07-11 | Soft start control circuit applied to electric power product |
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| Publication Number | Publication Date |
|---|---|
| CN111725985A true CN111725985A (en) | 2020-09-29 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010665527.1A Withdrawn CN111725985A (en) | 2020-07-11 | 2020-07-11 | Soft start control circuit applied to electric power product |
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| CN (1) | CN111725985A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114336887A (en) * | 2022-01-10 | 2022-04-12 | 苏州贝克微电子股份有限公司 | Power supply circuit with low cost and high reliability |
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|---|---|---|---|---|
| CN202309506U (en) * | 2011-10-12 | 2012-07-04 | 深圳麦格米特电气股份有限公司 | Chip-soft-start control circuit |
| US20140098452A1 (en) * | 2012-10-09 | 2014-04-10 | Fsp Technology Inc. | Power supply apparatus relating to dc-dc voltage conversion and having short protection function |
| US20140320483A1 (en) * | 2013-04-24 | 2014-10-30 | Shenzhen China Star Optoelectronics Technology Co., Ltd. | Start control circuit, display panel driving circuit and display device |
| CN104135146A (en) * | 2014-07-29 | 2014-11-05 | 广州金升阳科技有限公司 | Soft starting method and circuit |
| CN104917366A (en) * | 2015-06-23 | 2015-09-16 | 杭州中恒派威电源有限公司 | Quasi-resonant Boost soft start circuit |
| CN206922645U (en) * | 2016-12-30 | 2018-01-23 | 惠州市康冠科技有限公司 | A kind of soft starting circuit of power switch |
| CN109412400A (en) * | 2018-11-26 | 2019-03-01 | 珠海格力电器股份有限公司 | Inverse-excitation type switch power-supply and its under-voltage protecting circuit |
| CN209435105U (en) * | 2019-02-20 | 2019-09-24 | 广州视源电子科技股份有限公司 | A kind of soft starting circuit and electronic equipment |
-
2020
- 2020-07-11 CN CN202010665527.1A patent/CN111725985A/en not_active Withdrawn
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202309506U (en) * | 2011-10-12 | 2012-07-04 | 深圳麦格米特电气股份有限公司 | Chip-soft-start control circuit |
| US20140098452A1 (en) * | 2012-10-09 | 2014-04-10 | Fsp Technology Inc. | Power supply apparatus relating to dc-dc voltage conversion and having short protection function |
| US20140320483A1 (en) * | 2013-04-24 | 2014-10-30 | Shenzhen China Star Optoelectronics Technology Co., Ltd. | Start control circuit, display panel driving circuit and display device |
| CN104135146A (en) * | 2014-07-29 | 2014-11-05 | 广州金升阳科技有限公司 | Soft starting method and circuit |
| WO2016015566A1 (en) * | 2014-07-29 | 2016-02-04 | 广州金升阳科技有限公司 | Soft start method and circuit |
| CN104917366A (en) * | 2015-06-23 | 2015-09-16 | 杭州中恒派威电源有限公司 | Quasi-resonant Boost soft start circuit |
| CN206922645U (en) * | 2016-12-30 | 2018-01-23 | 惠州市康冠科技有限公司 | A kind of soft starting circuit of power switch |
| CN109412400A (en) * | 2018-11-26 | 2019-03-01 | 珠海格力电器股份有限公司 | Inverse-excitation type switch power-supply and its under-voltage protecting circuit |
| CN209435105U (en) * | 2019-02-20 | 2019-09-24 | 广州视源电子科技股份有限公司 | A kind of soft starting circuit and electronic equipment |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114336887A (en) * | 2022-01-10 | 2022-04-12 | 苏州贝克微电子股份有限公司 | Power supply circuit with low cost and high reliability |
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Application publication date: 20200929 |