CN104426336A - Switching circuit - Google Patents
Switching circuit Download PDFInfo
- Publication number
- CN104426336A CN104426336A CN201410432982.1A CN201410432982A CN104426336A CN 104426336 A CN104426336 A CN 104426336A CN 201410432982 A CN201410432982 A CN 201410432982A CN 104426336 A CN104426336 A CN 104426336A
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- China
- Prior art keywords
- led
- primary side
- optical coupler
- circuit
- output
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- 230000003287 optical effect Effects 0.000 claims abstract description 32
- 230000007704 transition Effects 0.000 claims abstract description 18
- 238000006243 chemical reaction Methods 0.000 claims abstract description 17
- 238000004804 winding Methods 0.000 claims abstract description 17
- 238000001514 detection method Methods 0.000 claims abstract description 9
- 230000001105 regulatory effect Effects 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 6
- 239000003990 capacitor Substances 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 238000012544 monitoring process Methods 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 230000036316 preload Effects 0.000 description 2
- 230000010349 pulsation Effects 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 230000004913 activation Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
Classifications
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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
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33538—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only of the forward type
- H02M3/33546—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only of the forward type with automatic control of the output voltage or current
- H02M3/33553—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only of the forward type with automatic control of the output voltage or current with galvanic isolation between input and output of both the power stage and the feedback loop
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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
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
- H02M1/092—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices the control signals being transmitted optically
-
- 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
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33507—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters
- H02M3/33515—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters with digital control
Abstract
The invention provides a switching conversion circuit, comprising: a transformer has a primary winding, a secondary winding, and an auxiliary winding. The optical coupler device includes an LED. A primary side regulation switch control circuit has a terminal receiving feedback from the optocoupler device to initiate a switching transition when the output voltage is below a target value or when the LED is off. When the output is lower than the target value, the secondary side detection circuit turns on the LED.
Description
Technical field
The present invention relates to a kind of conversion switch.The present invention relates more particularly to a kind of optical coupler feedback control circuit of low standby power.
Background technology
Now is having the demand constantly reduced to the standby power of power supply and charger apparatus.The application of NXP is explained AN11060 and is disclosed the method reduced for the standby power of primary side by-pass cock conversion equipment.U.S. Patent application US2012/01341484A1 discloses a kind of method three-prong device being increased to primary side, and when needing the additional energy changed from primary side, this device is via the secondary winding of transformer and auxiliary winding notice primary side.Preload because this three-prong device itself can be used as low dissipation, thus greatly can improve or even exempt the value of preload resistor, so which improve the standby power of the accuracy of control and the dynamic loading response of secondary voltage and minimizing primary side.No. US2013/0088898A1 U.S. patent applications disclose the use of aforementioned three-prong device and the Switching Two bipolar transistor at primary side place reuse amplify starting current.Therefore, the startup resistor at primary side place can have larger value and makes can reduce relating power upon actuation.
With regard to using the switch power change-over circuit of optical coupler feedback, some technology described in application note of NXP can be applied to primary side.High voltage and current source is used for starting, and can be turned off upon actuation.During off state, this start-up circuit has low leakage current.Another key technology reducing standby power is the use of the trigger mode (burst mode) with the primary switch electric current reduced.Typical structure chart as shown in Figure 1.The LED of optical coupler inside is connected to primary side.Output detection circuit (U2) exports whether reach its target level for judging.When output reaches its desired value, detector circuit exports and controls LED described in conducting.At primary side place, due to the conducting of LED, photistor generation current, LED notifies that primary-side circuitry stops making switching action.When LED disconnects, switching action continues, and this shows to export lower than its desired value.So, whole circuit according to different load-up condition regulation outputs until its desired value.
Although the circuit shown in Fig. 1 is with fabulous dynamic loading responsive operation, the standby power at primary side place is higher.With regard to the dc-dc converter that 5V exports, the LED current for typical optical coupler is 2mA or more.Do not consider output detection circuit, also do not consider the efficiency losses during switch transition, the conducting power being used for LED in standby period is 5V × 2mA, or 10mW.When target output voltage is higher, this loss is in rising.
Disputable, the LED starting switch of the optical coupler under conducting state can be used to change, and use the LED disable switch conversion of the optical coupler under off-state.But, when this device is by cold start-up, this simple logic inversion can not be applied.During cold start-up, secondary-side voltage is zero, thus the enough power do not had for secondary testing circuit is so that driving LED works (LED turns off and means that disable switch is changed, but switch transition should be started at this moment).The conducting of this choice for use LED exactly carrys out inactive power transfer and uses the shutoff of LED to carry out the reason of inactive power transfer.
Fig. 2 illustrates these two selections, and illustrates during cold start-up, Hui Chu Now conflict situation when reverse logic is used for existing selection as shown in Figure 1.
Summary of the invention
The object of the invention is to overcome or specifically upper improve above-mentioned defect and/or more mainly improve in primary side energy-conservation.
Disclose a kind of conversion switch at this, comprising:
There is the transformer of armature winding, secondary winding and auxiliary winding;
There is the optical coupler apparatus of LED and photistor;
Primary side by-pass cock control circuit, it uses auxiliary winding monitor the output voltage of primary side during the switch transition cycle, and has and receive the terminal of feedback from optically coupled device thus change lower than starting switch during desired value or when LED turns off at output voltage.
Primary side testing circuit, it is at the LED of output lower than optical coupler described in conducting during desired value.
As preferably, primary side by-pass cock control circuit is integrated into single integrated circuit (IC) with the feedback control circuit associated with optical coupler at primary side place.
As preferably, the voltage detecting circuit of primary side and be integrated into single three terminal integrated circuits (IC) for the LED drive circuit of the LED of optical coupler.
As preferably, the voltage and current testing circuit of primary side and be integrated into single four terminal integrated circuits (IC) for the LED drive circuit of the LED of optical coupler.
The method of Xie Decision logic conflict during cold start-up, be will when the operation level of secondary-side voltage lower than the LED of secondary side detector circuit and optical coupler, switch transition will still be started.
With regard to cold start-up, when the VDD at primary side place reaches initiation voltage level, switch transition starts.During each switch periods, in fact with the identical regulative mode of primary side, the output voltage of primary side can be obtained from the auxiliary winding of transformer.The target operation level selecting a triggering level value less than or equal to the VDD level of normal work (it corresponds to the output voltage less than or equal to target output voltage) to regulate as primary side, just can maintain switch transition.The voltage that this level need guarantee outlet side higher than the minimum of the LED of primary side testing circuit and optical coupler, thus suitably plays a role.Therefore an overlapping region is had, namely all can the region of starting switch conversion both primary side regulable control and optical coupler feedback.This overlap is guaranteed can not stop lower than switch transition during target output voltage at output-voltage levels.
Accompanying drawing explanation
Fig. 1 is the schematic diagram of the switched power change-over circuit of prior art;
Fig. 2 describes a pair voltage diagram having the start-up situation of conflict in the conversion switch of prior art;
Fig. 3 illustrates the signal logic diagram solving the logic conflict shown in Fig. 2 (b);
Fig. 4 is the possible design embodiments based on principle as discussed above; And
Fig. 5 is the schematic block diagram of another embodiment together with transformer secondary circuit.
Embodiment
Now preferred form of the present invention is described Fig. 3 and Fig. 5 by example reference accompanying drawing.
With reference to Fig. 3 and Fig. 4, illustrate that optical coupler FEEDBACK CONTROL is increased to primary side by-pass cock converter circuit as follows, wherein in figure 3, first side regulates target Vo to be equal to or greater than target Vo.
The conducting of optical coupler LED can starting switch operation.In other words, can regard as and primary side regulable control is increased to the switching converter circuit with optical coupler feedback, make to operate by starting switch during the LED conducting of optical coupler.In either case, switch transition operation is that probable logic starts.
In the diagram, T1 is for using PSW as the transformer needed for the switch transition of device for power switching.Diode D1, D2, D3 and D4 form bridge rectifier AC input being converted to pulsation DC, and described pulsation DC is filtered into high voltage DC by capacitor C1, and described high voltage DC is used as the power supply input of the armature winding of transformer T1.
Between the starting period, Closing Switch SW1 and starting current source Isu charge to VDD decoupling capacitor C2 the level that switch transition starts.Then SW1 be turned off and switching manipulation will proceed until primary side place output voltage first time reach target level.Then will start according to secondary output voltage or disable switch conversion thus maintain secondary voltage at desired value place.
The activation member of primary side controls to start order, and switch control device (IC) processes switch transition operation.
When switch transition is started, switch control device (IC) produces the output signal SWC with correct duty ratio, and described output signal SWC is used as the input of the driver (DRV) of main switching device PSW.Primary side switch current is measured by utilizing the voltage at CS monitoring nodes resistor R3 place.When PSW conducting, the primary inductance storage power of transformer T1.When PSW turns off, the energy transferring of this storage is to the primary side of transformer T1 and secondary side.In primary side, diode D7 carries out rectification to the signal of the secondary winding from transformer T1.Capacitor C4 is output filter.Output detector circuit U 2 monitors output voltage Vo.When Vo is lower than desired value, the LED of comparator A1 conducting optical coupler U1 is to indicate the more power of primary circuit transmission.When Vo is higher than desired value, comparator A1 will turn off the LED of optical coupler U1 to notify primary circuit shutdown switch conversion operations.By this way, output voltage is adjusted to its desired value.During each switch transition cycle, the auxiliary winding of transformer T1 also provides energy to charge to VDD decoupling capacitor C2 via diode D6.
Diode D5, resistor R2 and capacitor C3 form buffer circuit to absorb transient energy, make to reduce ringing during switch.
Resistor R7 with R8 is together with primary side regulation voltage sensing circuit U3, and during each switch transition cycle, energy transferring monitors output voltage to during primary side by the voltage at the auxiliary winding place of monitoring.When primary side output voltage is lower than target, the output of comparator A2 will be high level, starting switch conversion operations.
Another way directly can perform primary side at VDD Nodes and regulate sensing.
Logic sum gate G1 combines from " enable " signal of primary side adjustment and the feedback signal from optical coupler, make when secondary voltage is lower than target, time even the most extreme, during the minimum operation voltage of output voltage lower than output detector circuit U 2 and optical coupler LED, switch transition operation can be started.
Detect and LED driver circuit (U2) place in secondary-side voltage, compared with the situation in Fig. 1, the input of comparator A1 has been exchanged.This means that the conducting of the LED of optical coupler is the logic inversion in the situation of Fig. 1.U2 in Fig. 4 can be integrated in three terminal devices.
Secondary output voltage is detected and LED driver circuit decision by the secondary-side voltage with fabulous dynamic loading response substantially.Hysteresis can add voltage detecting circuit.This is by increase output ripple voltage and reduce standby power further.
Can modify to merge output electric current measure function to secondary-side voltage detection and LED driver circuit, make described device become output voltage and current sensing means.Fig. 5 is the block diagram together with transformer secondary circuit.In Figure 5, resistor R1 converts output current to voltage, is monitored by current detector.A3, to having appropriate gain coefficient " differential turn single-ended " amplifier, mates current limit with reference voltage Vref.The output current measured and its limit compare by comparator A2.Resistor R2 with R3 plays with comparator A1 the effect monitoring output voltage together in mode identical in Fig. 4.The LED of the optical coupler U1 at secondary circuit place at output voltage and output current lower than conducting during target.This voltage and current testing circuit can be integrated into four-terminal device (U2).By using this device with above-mentioned primary-side circuitry in Fig. 4, CV/CC switch transition can be realized.
Claims (7)
1. a conversion switch, comprising:
There is the transformer of armature winding, secondary winding and auxiliary winding;
There is the optical coupler apparatus of LED and photistor;
Primary side by-pass cock control circuit, and there is the additional terminals receiving feedback from described optical coupler apparatus, wherein changed by primary side by-pass cock control circuit starting switch lower than during desired value or when the LED of described optical coupler apparatus turns off at output voltage; And
Primary side output detections and LED driver circuit, in order to exporting lower than the LED of optical coupler apparatus described in conducting during desired value.
2. conversion switch according to claim 1, the switch transition circulation of wherein said ON-OFF control circuit is regulated by primary side or is started by the conducting of the LED of described optical coupler apparatus.
3. conversion switch according to claim 2, wherein said ON-OFF control circuit is integrated into single integrated circuit (IC).
4. switching converter circuit according to claim 1, wherein said primary side output detection circuit and LED driver circuit detect the output voltage at the primary side place of described transformer, and provide and drive with at the LED of described output lower than optical coupler apparatus described in conducting during described desired value.
5. conversion switch according to claim 4, wherein said output detection circuit and LED driver circuit are integrated into single three terminal devices.
6. conversion switch according to claim 1, wherein said primary side output detection circuit and LED driver circuit detect described output voltage and electric current, and provide drive with at described output voltage and output current all lower than the LED of optical coupler apparatus described in conducting during desired value.
7. conversion switch according to claim 6, wherein said output detection circuit and LED driver circuit are integrated into single four-terminal device.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| HK13110093.0 | 2013-08-29 | ||
| HK13110093.0A HK1186345A2 (en) | 2013-08-29 | 2013-08-29 | Switching conversion circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN104426336A true CN104426336A (en) | 2015-03-18 |
Family
ID=50240184
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410432982.1A Pending CN104426336A (en) | 2013-08-29 | 2014-08-28 | Switching circuit |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN104426336A (en) |
| HK (1) | HK1186345A2 (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006187054A (en) * | 2004-12-24 | 2006-07-13 | Canon Inc | Switching regulator |
| JP2009201331A (en) * | 2008-02-25 | 2009-09-03 | Seiko Epson Corp | Switching power supply circuit |
| CN101997534A (en) * | 2009-08-13 | 2011-03-30 | 立锜科技股份有限公司 | Feedback circuit and control method for isolated power converter |
-
2013
- 2013-08-29 HK HK13110093.0A patent/HK1186345A2/en not_active IP Right Cessation
-
2014
- 2014-08-28 CN CN201410432982.1A patent/CN104426336A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006187054A (en) * | 2004-12-24 | 2006-07-13 | Canon Inc | Switching regulator |
| JP2009201331A (en) * | 2008-02-25 | 2009-09-03 | Seiko Epson Corp | Switching power supply circuit |
| CN101997534A (en) * | 2009-08-13 | 2011-03-30 | 立锜科技股份有限公司 | Feedback circuit and control method for isolated power converter |
Also Published As
| Publication number | Publication date |
|---|---|
| HK1186345A2 (en) | 2014-03-14 |
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Application publication date: 20150318 |