CN101154881A - Switch power circuit - Google Patents
Switch power circuit Download PDFInfo
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- CN101154881A CN101154881A CNA2006100628957A CN200610062895A CN101154881A CN 101154881 A CN101154881 A CN 101154881A CN A2006100628957 A CNA2006100628957 A CN A2006100628957A CN 200610062895 A CN200610062895 A CN 200610062895A CN 101154881 A CN101154881 A CN 101154881A
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Abstract
The invention relates to a switch power circuit, comprising a power input end, a main power control chip, and a soft start unit. The power input end provides working voltage for the switch power circuit; the soft start unit comprises a first resistance, a second resistance, a capacitor, an optical coupler and a first transistor working in an amplified state. The base electrode of the first transistor is connected with the power input end through the second resistance and the capacitor; the collecting electrode is connected with the power input end through the optical coupler and the first resistance; the emitting electrode is connected to the ground. The main power control chip conducts pulse-width modulation to the output current from the optical coupler so as to get the outputting pulse width voltage of the switch power circuit.
Description
Technical field
The present invention relates to a kind of switching power circuit.
Background technology
Because advantages such as Switching Power Supply possesses gently, approaches, power consumption is little have been widely used in the electronic products such as portable product, aviation and automated production, instrument and meter.Yet in switch transition moment, owing to have reactance component in the circuit, along with the energy of reactance component charges and discharge, power component can be subjected to super-high-current and heat energy impacts, thereby causes component failure, and the switching power circuit reliability reduces.Therefore, for improving the switching power circuit reliability, a slow start unit (Snubber Circuit) need be set so that suppressing overcurrent produces, effectively the protective circuit element.
Fig. 1 is a kind of circuit diagram of prior art switching power circuit.This switching power circuit 10 comprises a first input end 11, one second input 12, a partial pressure unit 13, a voltage regulation unit 14, one slow start unit 15, a main power control chip 16 and a power output end 17.This first input end 11 and this second input 12 be respectively this switching power circuit 10 provide+5V and+operating voltage of 12V.This partial pressure unit 13 outputs one partial pressure value is to this voltage regulation unit 14, and this partial pressure value is the voltage stabilizing reference value of this voltage regulation unit 14.When the electric current of this slow start unit 15 of flowing through too small and when causing the output pulse width voltage of this switching power circuit 10 excessive, this voltage regulation unit 14 is controlled and is adjusted the size of current of this slow start unit 15 of flowing through, thereby makes the output pulse width voltage of this switching power circuit 10 be no more than this voltage stabilizing reference value.Warp should delay start unit 15 buffered+5V operating voltage, transferred to this power output end 17 via this main power control chip 16.The output voltage of this power output end 17 is powered to load (figure does not show) via a transformer (figure does not show).
This partial pressure unit 13 comprises three resistance 131,132,133 and a dividing potential drop node 134.11 inputs of this first input end+the 5V operating voltage is successively via this first resistance 131, this dividing potential drop node 134 and the 3rd resistance 133 ground connection.12 inputs of this second input+the 12V operating voltage is successively via this second resistance 132, this dividing potential drop node 134 and the 3rd resistance 133 ground connection.The output voltage of this dividing potential drop node 134 transfers to this voltage regulation unit 14, and its output voltage values is the voltage stabilizing reference value of this voltage regulation unit 14, can calculate according to Kirchhoff's law (Kirchhoff ' s Law).
Should comprise one the 4th resistance 151, one the 5th resistance 152, a diode 153, an electric capacity 154 and an optical coupler 155 by slow start unit 15.First input end 11 input+the 5V operating voltage has two output channels, the one output channel is successively via the 4th resistance 151, this optical coupler 155, this diode 153 and this electric capacity 154 ground connection, and another output channel is via the 5th resistance 152 and this electric capacity 154 ground connection.This diode 153 is generally IN4148.
This optical coupler 155 comprises a transistor 156 and a light-emitting diode 157.This transistor 156 comprises a base stage (not indicating), an emitter (not indicating) and a collector electrode (not indicating), thereby its base stage induction makes this transistor 156 conductings from the light particle of these light-emitting diode 157 outgoing, and its collector electrode is connected an operating voltage V via a current-limiting resistance 158
Ss, emitter outputs current to this main power control chip 16.This main power control chip 16 can be carried out pulse-width modulation with the output current and a sawtooth pulse of optical coupler 155, thereby the pulsewidth voltage that obtains being inversely proportional to optical coupler 155 output current sizes is to this power output end 17.
This voltage regulation unit 14 comprises one or three ends shunt regulator able to programme (Three-terminal Shunt Regulator) 141 and has the RC series circuit of filter function (not indicating).This three end shunt regulator 141 able to programme can be TL431, and it comprises that an anode 1411, a negative electrode 1412 and are with reference to the utmost point 1413.This negative electrode 1412 is connected to an end of this RC series circuit, and anode 1411 ground connection are connected to this dividing potential drop node 134 with reference to the utmost point 1413 via the other end of this RC series circuit.When and pulsewidth voltage that cause this power output end 17 export too small when the electric current I of this optical coupler 155 of flowing through is excessive, the cathode terminal of level to the light-emitting diode 157 of this optical coupler 155 adjusted in negative electrode 1412 outputs one of this three end shunt regulator 141 able to programme, thereby regulate the size of this electric current I, make the output pulse width voltage of this switching power circuit 10 be no more than this voltage stabilizing reference value.
When this switching power circuit 10 starts, these diode 153 conductings, first input end 11 input+the 5V operating voltage respectively via the output channel at the output channel at the 4th resistance 151, this optical coupler 155 and this diode 153 places and the 5th resistance 152 places to these electric capacity 154 chargings.Along with the charging voltage of electric capacity 154 raises gradually, the electric current I of light-emitting diode 157 of this optical coupler 155 of causing flowing through reduces gradually, then the light particle of these light-emitting diode 157 emissions reduces gradually, the output current of this transistor 157 is reduced gradually, thereby cause the output pulse width of this main power control chip 16 to increase gradually, then the voltage of this power output end 17 raises gradually, charging voltage rising up to this electric capacity 154 makes this diode 153 oppositely end, and this switching power circuit 10 is finished slow start-up operation.Afterwards, these switching power circuit 10 stable outputs.Simultaneously, this first input end 11 continues 154 chargings of this electric capacity via the 5th resistance 152, up to the charging voltage of this electric capacity 154 reach+5V till.
Because the electric capacity 154 of above-mentioned slow start unit 15 need bear+charging voltage of 5V, and in its charging process, need bear bigger charging current, therefore, this electric capacity 154 only can select to have the electrochemical capacitor of big volumetric properties.Yet the electrochemical capacitor volume is bigger, causes the volume of this slow start unit 15 bigger, thereby causes using the switching power circuit 10 of this slow start unit 15 not to be suitable for miniaturization, microminiaturized electronic device.
Summary of the invention
In order to solve the excessive problem of switching power circuit volume that causes because of the soft-start circuit volume is excessive in the prior art, be necessary to provide a kind of switching power circuit with smaller size smaller.
A kind of switching power circuit, it comprises a power input, a main power control chip and a slow start unit.This power input provides operating voltage for this switching power circuit.Should comprise that one first resistance, one second resistance, an electric capacity, an optical coupler and were operated in the first transistor of magnifying state by slow start unit.The base stage of this first transistor is connected this power input via this second resistance and this electric capacity, and collector electrode is connected this power input, grounded emitter via this optical coupler and this first resistance.This main power control chip is carried out pulse-width modulation with the output current of this optical coupler, thereby obtains the output pulse width voltage of this switching power circuit.
Compared with prior art, the slow start unit of this switching power circuit is to be made of jointly electric capacity, optical coupler, a plurality of resistance and the transistor that is operated in magnifying state.Because this transistor is operated in magnifying state, the current strength of this electric capacity of then flowing through is less, and the charging voltage of electric capacity only need be increased to this transistor is ended till, can not reach the operating voltage that power input provides.Therefore, the capacity of required electric capacity is less, only need use the ceramic disc capacitor of low capacity to get final product.Because it is little that ceramic disc capacitor has a volume than electrochemical capacitor, therefore, the volume of this slow start unit is less, thereby guarantees to use the switching power circuit of this slow start unit to be applicable to miniaturization, microminiaturized electronic device.
Description of drawings
Fig. 1 is a kind of circuit diagram of prior art switching power circuit.
Fig. 2 is the circuit diagram of switching power circuit one better embodiment of the present invention.
Embodiment
Seeing also Fig. 2, is the circuit diagram of switching power circuit one better embodiment of the present invention.This switching power circuit 20 comprises a first input end 21, one second input 22, a partial pressure unit 23, a voltage regulation unit 24, one slow start unit 25, a main power control chip 26 and a power output end 27.This first input end 21 and this second input 22 be respectively this switching power circuit 20 provide+5V and+operating voltage of 12V.This partial pressure unit 23 outputs one partial pressure value is to this voltage regulation unit 24, and this partial pressure value is the voltage stabilizing reference value of this voltage regulation unit 24.When the electric current of this slow start unit 25 of flowing through too small and when causing the output pulse width voltage of this switching power circuit 20 excessive, this voltage regulation unit 24 is controlled and is adjusted the size of current of this slow start unit 25 of flowing through, thereby makes the output pulse width voltage of this switching power circuit 20 be no more than this voltage stabilizing reference value.Warp should delay start unit 25 buffered+5V operating voltage, transferred to this power output end 27 after handling via this main power control chip 26 again.The output voltage of this power output end 27 is powered to load (figure does not show) via a transformer (figure does not show).
This partial pressure unit 23 comprises three resistance 231,232,233 and a dividing potential drop node 234.21 inputs of this first input end+the 5V operating voltage is successively via this first resistance 231, this dividing potential drop node 234 and the 3rd resistance 233 ground connection.22 inputs of this second input+the 12V operating voltage is successively via this second resistance 232, this dividing potential drop node 234 and the 3rd resistance 233 ground connection.The output voltage of this dividing potential drop node 234 transfers to this voltage regulation unit 24, and its output voltage values is the voltage stabilizing reference value of this voltage regulation unit 24, can calculate according to Kirchhoff's law.
Should comprise one the 4th resistance 251, one the 5th resistance 252, an electric capacity 254, a triode 253 and an optical coupler 255 by slow start unit 25.
This triode 253 comprises a base stage 2531, a collector electrode 2532 and an emitter 2533, its base stage 2531 is connected this first input end 21 via the 5th resistance 252, this electric capacity 254, collector electrode 2532 is connected this first input end 21 via this optical coupler 255 and the 4th resistance 251, emitter 2533 ground connection.This triode 253 is SMD NPN type triode.
This optical coupler 255 comprises a transistor 256 and a light-emitting diode 257.This transistor 256 comprises a base stage (not indicating), an emitter (not indicating) and a collector electrode (not indicating), thereby its base stage induction makes this transistor 256 conductings from the light particle of these light-emitting diode 257 outgoing, and its collector electrode is connected to an operating voltage V via a current-limiting resistance 258
Ss, emitter outputs current to this main power control chip 26.This main power control chip 26 can be carried out pulse-width modulation with the output current and a sawtooth pulse of optical coupler 255, thereby the pulsewidth voltage that obtains being inversely proportional to optical coupler 255 output current sizes is to this power output end 27.
This voltage regulation unit 24 comprises one or three ends shunt regulator 241 able to programme and has the RC series circuit of filter function (not indicating).This three end shunt regulator 241 able to programme can be TL431, and it comprises that an anode 2411, a negative electrode 2412 and are with reference to the utmost point 2413.This negative electrode 2412 is connected to an end of this RC series circuit, and anode 2411 ground connection are connected to this dividing potential drop node 234 with reference to the utmost point 2413 via the other end of this RC series circuit.When and pulsewidth voltage that cause this power output end 27 export too small when the electric current I of this optical coupler 255 of flowing through is excessive, the cathode terminal of level to the light-emitting diode 257 of this optical coupler 255 adjusted in negative electrode 2412 outputs one of this three end shunt regulator 241 able to programme, thereby regulate the size of this electric current I, make the output pulse width voltage of this switching power circuit 20 be no more than this voltage stabilizing reference value.
When this switching power circuit 20 starts, these first input end 21 inputs+the 5V operating voltage is via this electric capacity 254 and the 5th resistance 255 these triodes 253 of control.Start moment, this electric capacity 254 is equivalent to short circuit, then the base current I of this triode 253
bMaximum, thus make this triode 253 conductings.Along with the charging voltage of this electric capacity 254 raises gradually, this base current I then
bReduce gradually, the electric current I of this optical coupler 255 of causing flowing through reduces gradually, then light-emitting diode 257 outgoing of this optical coupler 255 to the photon number of these transistor 256 base stages reduces gradually, the emitter output current of this optical coupler 255 reduces gradually, and the output pulse width voltage of this main power control chip 26 increases gradually.When the charging voltage of this electric capacity 254 makes base current I
bThereby when reducing to make this triode 253 to end, this switching power circuit 20 is finished slow start-up operation.Afterwards, these first input end 21 inputs+the 5V operating voltage continues power supply via 251 pairs of these optical couplers of the 4th resistance 255, and the outputting current steadily of this optical coupler 255, and this main power control chip 26 is stablized output.
Emulation experiment proves that when selecting for use capacity to be the electric capacity 254 of 0.1Mf, the slow start-up course required time of this switching power circuit 20 is 0.4 millisecond.
The slow start unit 25 of this switching power circuit 20 is made of jointly electric capacity 254, optical coupler 255, a plurality of resistance and the triode 253 that is operated in magnifying state.Because this triode 253 is operated in magnifying state, the current strength of this electric capacity 254 of flowing through is less, and the charging voltage of electric capacity 254 only need be increased to this triode 253 is ended till, can not continue to charge to 5V.Therefore, the capacity of required electric capacity 254 is less, only need use the ceramic disc capacitor of low capacity to get final product.Because ceramic disc capacitor has the little characteristics of volume than electrochemical capacitor, and triode 253 also can adopt SMD triode, therefore, the volume of this slow start unit 25 is less, thereby guarantees to use the switching power circuit 20 of this slow start unit 25 to be applicable to miniaturization, microminiaturized electronic device.
In addition, the triode 253 of above-mentioned switching power circuit 20 slow start units 25 also can be the positive-negative-positive triode.
Claims (10)
1. switching power circuit, it comprises one first power input, an one slow start unit and a main power control chip, this first power input provides operating voltage for this switching power circuit, should comprise an optical coupler by slow start unit, this main power control chip is carried out pulse-width modulation with the output current of this optical coupler, thereby export the pulsewidth voltage of this switching power circuit, it is characterized in that: this slow start unit further comprises one first resistance, one second resistance, one electric capacity and one is operated in the first transistor of magnifying state, the base stage of this first transistor is connected this power input via this second resistance and this electric capacity, its collector electrode is connected this first power input, grounded emitter via this optical coupler and this first resistance.
2. switching power circuit as claimed in claim 1 is characterized in that: this electric capacity is ceramic disc capacitor, and this first transistor is SMD transistor.
3. switching power circuit as claimed in claim 2 is characterized in that: this first transistor is NPN type triode or positive-negative-positive triode.
4. switching power circuit as claimed in claim 1 is characterized in that: this optical coupler comprises a light-emitting diode and a transistor seconds, and this light-emitting diode emergent light particle drives this transistor seconds conducting.
5. switching power circuit as claimed in claim 1 is characterized in that: the pulsewidth voltage of this main power control chip output and the output current size of this optical coupler are inversely proportional to.
6. switching power circuit as claimed in claim 1 is characterized in that: this switching power circuit further comprises a second source input, and the magnitude of voltage of this second source input is+12V that the magnitude of voltage of this first power input is+5V.
7. switching power circuit as claimed in claim 6, it is characterized in that: this switching power circuit further comprises a partial pressure unit and a voltage regulation unit, this partial pressure unit is carried out dividing potential drop with the operating voltage that this first power input and this second source input are provided, thereby export a reference value to this voltage regulation unit, the output current size that this voltage regulation unit is adjusted this slow start unit optical coupler is no more than this reference value with the pulsewidth voltage of controlling this main power control chip output.
8. switching power circuit as claimed in claim 7, it is characterized in that: this voltage regulation unit comprises that one or three ends shunt regulator able to programme and has the RC series circuit of filter function, this three end shunt regulator able to programme comprises that a negative electrode, an anode and are with reference to the utmost point, this negative electrode is connected an end of this RC series circuit, this plus earth, this is connected this bleeder circuit output reference value place with reference to the utmost point via the other end of this RC series circuit.
9. as claim 8 a described switching power circuit, it is characterized in that: this partial pressure unit comprises one the 3rd resistance, one the 4th resistance and one the 5th resistance, the operating voltage of this first power input input is successively via the 3rd resistance and the 5th grounding through resistance, and the operating voltage of this second input input is successively via the 4th resistance and the 5th grounding through resistance.
10. switching power circuit as claimed in claim 8 is characterized in that: this three end shunt regulator able to programme is TL431.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006100628957A CN100530914C (en) | 2006-09-29 | 2006-09-29 | Switch power circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006100628957A CN100530914C (en) | 2006-09-29 | 2006-09-29 | Switch power circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101154881A true CN101154881A (en) | 2008-04-02 |
| CN100530914C CN100530914C (en) | 2009-08-19 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2006100628957A Expired - Fee Related CN100530914C (en) | 2006-09-29 | 2006-09-29 | Switch power circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN100530914C (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101577493B (en) * | 2008-05-07 | 2011-06-15 | 群康科技(深圳)有限公司 | Power supply circuit |
| CN101714813B (en) * | 2009-12-15 | 2012-06-06 | 天水华天微电子股份有限公司 | Soft start circuit of switch power supply |
| CN102751698A (en) * | 2012-07-20 | 2012-10-24 | 冠捷显示科技（厦门）有限公司 | Overvoltage protection circuit, power module and overvoltage protection method |
| CN101673956B (en) * | 2008-09-12 | 2013-01-30 | 力博特公司 | UPS soft start circuit and method |
| CN108832667A (en) * | 2018-05-03 | 2018-11-16 | 许继电源有限公司 | A kind of SS (soft start) control circuit applied to control switch power supply direct current output |
| CN110113845A (en) * | 2019-06-06 | 2019-08-09 | 湖南凯上电子科技有限公司 | A kind of LED illumination power supply eyeshield SS (soft start) control circuit |
-
2006
- 2006-09-29 CN CNB2006100628957A patent/CN100530914C/en not_active Expired - Fee Related
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101577493B (en) * | 2008-05-07 | 2011-06-15 | 群康科技(深圳)有限公司 | Power supply circuit |
| CN101673956B (en) * | 2008-09-12 | 2013-01-30 | 力博特公司 | UPS soft start circuit and method |
| CN101714813B (en) * | 2009-12-15 | 2012-06-06 | 天水华天微电子股份有限公司 | Soft start circuit of switch power supply |
| CN102751698A (en) * | 2012-07-20 | 2012-10-24 | 冠捷显示科技（厦门）有限公司 | Overvoltage protection circuit, power module and overvoltage protection method |
| CN102751698B (en) * | 2012-07-20 | 2015-09-30 | 冠捷显示科技（厦门）有限公司 | Excess voltage protection, power module and over-voltage protection method |
| CN108832667A (en) * | 2018-05-03 | 2018-11-16 | 许继电源有限公司 | A kind of SS (soft start) control circuit applied to control switch power supply direct current output |
| CN108832667B (en) * | 2018-05-03 | 2020-09-25 | 许继电源有限公司 | Soft start control circuit applied to control of DC output of switching power supply |
| CN110113845A (en) * | 2019-06-06 | 2019-08-09 | 湖南凯上电子科技有限公司 | A kind of LED illumination power supply eyeshield SS (soft start) control circuit |
| CN110113845B (en) * | 2019-06-06 | 2024-03-22 | 湖南凯上电子科技有限公司 | Eye protection soft start control circuit of LED illumination power supply |
Also Published As
| Publication number | Publication date |
|---|---|
| CN100530914C (en) | 2009-08-19 |
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Granted publication date: 20090819 Termination date: 20170929 |