CN202168002U - Primary-side control type power switch and alternating current-direct current converter - Google Patents
Primary-side control type power switch and alternating current-direct current converter Download PDFInfo
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- CN202168002U CN202168002U CN2011202903940U CN201120290394U CN202168002U CN 202168002 U CN202168002 U CN 202168002U CN 2011202903940 U CN2011202903940 U CN 2011202903940U CN 201120290394 U CN201120290394 U CN 201120290394U CN 202168002 U CN202168002 U CN 202168002U
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Abstract
The utility model provides a primary-side control type power switch which comprises a pulse-frequency modulation controller and a power transistor, wherein the pulse-frequency modulation controller comprises a noise suppression module, a line-voltage compensation module and a peak current control module; the noise suppression module is connected with the peak current control module to form a subsection of peak current; and the line-voltage compensation module is used for realizing that the output currents are consistent under different line voltages during application of constant current. The utility model discloses an alternating current-direct current converter at the same time.
Description
Technical field
The utility model relates to field of power conversion, relates in particular to the power switch of a kind of former limit control type and uses the A.C.-D.C. converter of this power switch.
Background technology
So-called former limit control type (being called for short PSR) is exactly common ASIC (Application Specific Integrated Circuit) scheme; Promptly save optocoupler and secondary constant pressure and flow controller, only adopt the application-specific integrated circuit (ASIC) on the former limit of transformer just can realize constant pressure and flow control output voltage.The technology of PSR scheme is ripe gradually, 20 watts of power outputs with interior AC-DC conversion in, replace the secondary scheme of band optocoupler just gradually.
The power switch of former limit control type then is that power device and PSR controller are integrated in the encapsulation, just can further reduce the parts number of system schema, to adapt to high-performance, small size, to be prone to production, market demands cheaply.
Mode of operation according to PSR scheme built-in controller is divided, and can the power switch of former limit control type be divided into two types, the power switch of the power switch of promptly built-in PWM (pulse width modulation) controller and built-in PFM (pulse frequency modulated) controller.The power switch of built-in PWM controller, its operating frequency is fixed, and is unfavorable for improving system's conversion efficiency, is difficult to satisfy increasingly high international efficiency standard.The power switch of built-in PFM controller, because the linear reduction along with load reduction of its operating frequency, so average efficiency is high, satisfies the international efficiency standard of main flow easily.But; The shortcoming of the power switch of the built-in PFM controller of simple mode is; Because its operating frequency is linear the reduction along with load reduction; Switching frequency is in the hundreds of hertz between the 20KHZ when just making underloading easily, just in time falls into the audibility range of people's ear, produces insufferable audio noise.
As shown in fig. 1, Fig. 1 is the noise test data figure of the power switch system of built-in PFM controller in the prior art.This power switch system fully loaded 40% when following, the noise that is sent can not be accepted by majority.According to test, the receptible criteria for noise of normal person is-below the 51dB.
In view of this, need the power switch system that wants a kind of built-in PFM controller newly in the prior art badly, this system had both suppressed than the audio noise under the light-load conditions, and kept the main body control pattern of basic PFM.
The utility model content
In order to overcome the defective that exists in the prior art; The utility model provides the power switch of a kind of former limit control type and uses the A.C.-D.C. converter of this power switch; Can promote than the switching frequency under the underload; Suppress audio noise, and realize that simultaneously average conversion efficiency is high, satisfies each item efficiency standard.
In order to realize the foregoing invention purpose; The utility model provides the power switch of a kind of former limit control type; Comprise: pulse frequency modulated controller and power transistor, this pulse frequency modulated controller comprises noise suppression module, line voltage compensation module and peak current control module; This noise suppression module is connected with this peak current control module to form a segmentation peak current; Output current unanimity under not collinear voltage when this line voltage compensation module is used in order to the realization constant current.
Further, this peak current control module is a peak current comparator, and this peak current comparator is connected with the base stage of this power transistor.
Further, this noise suppression module comprises that the logic control circuit that is connected with the CPC pin is used to produce a control signal, and this control signal is connected with this peak current control module through a control switch.
Further, also comprise one first resistance between this control switch and this peak current control module.
Further, this line voltage compensation module comprises first outer meeting resistance and second outer meeting resistance that is connected with the FB pin, and this first outer meeting resistance is connected with the auxiliary winding of second outer meeting resistance and transformer.
Further, this line voltage compensation module is connected with this peak current control module through second resistance; This FB pin is connected with the 3rd resistance, the 3rd grounding through resistance.
Further, this power transistor is double pole triode or FET.
The utility model discloses a kind of A.C.-D.C. converter simultaneously, comprising:
Power supply;
Transformer has the main winding that is coupled to this transformer, and this switch is used for receiving control signal to open or to cut out the electric current of main winding;
The output rectifier diode;
And the power switch of aforementioned former limit control type.
Further; This output rectifier diode conduction period; To obtain output voltage information, this output voltage information is by external first feedback resistance of the FB pin of this power switch and the sampling of second feedback resistance through induction secondary coil voltage for the auxiliary winding of this transformation.
Further, this A.C.-D.C. converter also comprises a RCD absorption circuit, the peak voltage that produces because of transformer leakage inductance and distributed capacitance when turn-offing in order to the absorbed power transistor.
The technical scheme of the utility model through a noise reducing circuit is set, promotes than the switching frequency under the underload compared with prior art, has reached the purpose that suppresses audio noise.Because agent structure still is the PFM mode, average conversion efficiency is still higher, satisfies various efficiency standards easily.The power switch of former limit control type; Also increase line voltage compensation circuit etc.; Output current is constant when realizing the input of not collinear voltage, for the constant current application of charger and LED lighting field provides performance guarantee, has not further promoted integrated level on the basis of peripheral components increasing.The A.C.-D.C. converter of employing inverse-excitation type transformer device structure disclosed in the utility model utilizes constant current output to replace overcurrent protection, and the EMI simplicity of design.The few reliability of this A.C.-D.C. converter number of elements is high, has complied with small sizes such as charger, LED, appliance network, application trend cheaply.
Description of drawings
Can detail and appendedly graphicly further understood through following utility model about the advantage of the utility model and spirit.
Fig. 1 is the noise test data figure of the power switch system of built-in PFM controller in the prior art;
Fig. 2 is the power switch working waveform figure of built-in PFM controller and power transistor in the prior art;
Fig. 3 is the circuit module figure of the A.C.-D.C. converter shown in the utility model;
Fig. 4 is the circuit module figure of built-in realization noise suppression of the power switch shown in the utility model and line voltage compensation;
Fig. 5 is the detailed circuit module map of built-in realization noise suppression of the power switch shown in the utility model and line voltage compensation;
Fig. 6 is the sketch map of the corresponding relation of operating frequency and load when not adding built-in noise suppression module in the prior art;
The sketch map of the corresponding relation of operating frequency and load when Fig. 7 is built-in noise suppression module;
Fig. 8 is the noise test data figure of the power switch system shown in the utility model.
Embodiment
Specify the specific embodiment of the utility model below in conjunction with accompanying drawing.
The utility model provides the power switch of a kind of former limit control type; This power switch built-in power device and pulse frequency modulated (PFM) controller, the PFM controller have here increased audio noise especially and have suppressed the underloading noise problem that circuit produces with the power-supply system that solves at present general PFM controller.This noise suppression module is provided with the segmentation peak current, when loading on fully loaded certain percentage when following, switches to less peak current the operating frequency than the underloading section is improved, and realizes noise suppression.The agent structure of this power switch still adopts the PFM mode, and average conversion efficiency is still higher, satisfies various efficiency standards easily.The PFM controller also increases the grid line voltage compensating circuit, output current basically identical when wide input voltage is used.Grid line voltage compensation described here is to realize through the outer meeting resistance that adjusting is connected in the Voltage Feedback pin of power switch, and this outer meeting resistance is connected with the auxiliary winding of transformer.
As shown in Figure 2, Fig. 2 is the power switch working waveform figure of built-in PFM controller and power transistor in the prior art.Vdri wherein, Ip, Is; Vs is the former limit of indication transformer switch drive respectively, primary current, secondary current and secondary voltage waveform; When converter was operated in pressure constant state, along with the increase of load current is to realize time that former limit and secondary all turn-off that constant voltage controls through the discontinuous time T off that changes secondary current, and the ON time Tons of secondary remained unchanged; The ON time Tonp on former limit also remains unchanged under the situation that keeps fixing at the former limit of transformer input voltage; Because the switch periods formula is: Tsw=Tonp+Tons+Toff, so switch periods is only relevant with Toff, Toff constantly increases when load current constantly reduces; Switch periods Tsw also and then increases, and promptly the operating frequency of converter is constantly reducing.
Operating frequency can be reduced to audiorange (20 hertz between the 20K hertz) when converter is operated in the underloading condition; Meeting such as the transformer in the converter produces audio-frequency noise, and the utility model makes the method for the operating frequency raising of underloading section realize the audio noise inhibition through in the inner increase of power switch noise suppression module the segmentation peak current being set.
Fig. 3 shows the circuit module figure according to the A.C.-D.C. converter of the power switch of the former limit control type of the built-in noise suppression module of use of an embodiment of the utility model.This figure only is a schematic illustration, does not therefore limit the scope of claim.Those skilled in the art can understand other distortion, change and variation.As shown in Figure 3, this A.C.-D.C. converter comprises power supply Vin.PFM controller and power transistor are integrated in power switch 100 the insides; Wherein the collector electrode of power transistor (also can be the drain electrode of FET; Later on roughly the same) connect the primary coil of transformer 101; Its emitter (also can be the source electrode of FET, later on roughly the same) links to each other with the inner CS pin of power switch, simultaneously the former limit peak current sample resistance 109 of an external very little resistance.The CS pin also links to each other with an end of peak current comparator in power switch inside; Switch-off power switch when the sampling voltage Vcs on the sample resistance 109 reaches the upset level of peak current comparator; Realize the NE BY ENERGY TRANSFER from the former limit of transformer to secondary through opening periodically with the switch-off power switch, obtaining stable direct current output at output simultaneously provides constant voltage and constant current to use.
In order to obtain better output voltage regulation; The A.C.-D.C. converter that constitutes based on the PFM controller of PSR is generally operational in electric current non-continuous mode (DCM); At secondary output diode 112 conduction period Tons; The auxiliary winding of transformer also is simultaneously that feedback winding Nfb obtains output voltage information through the voltage Vs on the induction secondary coil Ns; This information is fed back to the inner constant voltage control module of power switch simultaneously by external feedback resistance 110 of the FB pin of power switch 100 and 111 samplings, therefore realizes constant voltage work through the PSR control chip.This feedback resistance 110 also is used to improve line voltage compensation.
As shown in Figure 3, electric capacity 105 and resistance 106 parallel connection backs are connected with diode 107, constitute a RCD absorption circuit jointly, when turn-offing in order to the absorbed power transistor because of the peak voltage of transformer leakage inductance and distributed capacitance generation.In low power A.C.-D.C. converter, this absorption circuit can omit, and can realize this technical scheme equally.
The circuit module figure of built-in realization noise suppression of the power switch shown in the utility model and line voltage compensation as shown in Figure 4.The built-in PFM controller of this power switch because the agent structure of this PFM controller is consistent with prior art, is not therefore done detailed elaboration here.This power switch also comprises noise suppression module 11, line voltage compensation module 12, peak current control module 13 and power transistor 14.This noise suppression module is connected with the CPC pin, and the other end is connected with peak current control module 13.This line voltage compensation module 12 is connected with the FB pin, and the other end is connected with peak current control module 13.This peak current control module 13 is connected with emitter with the base stage of this NPN triode respectively.The collector and emitter of power transistor 14 is connected with the CS pin with the C pin respectively.Because this power switch adopts noise suppression module 11 process peak current control modules 13 to produce different benchmark Vcs_ref; Make the control of traditional constant peak current become the control of segmentation peak current, so the operating frequency during underloading significantly improve will control than constant peak current the time.
Below will introduce the detailed circuit diagram of the power switch of this built-in noise suppression module and line voltage compensation module.As shown in Figure 5, this power switch links to each other with several pins, and wherein the FB pin is used for receiving feedback information; Gnd pin ground connection; The C pin connects the collector electrode of power transistor; The Vcc pin is used to receive operating power; The CPC pin is used to receive capacitance signal; The CS pin is through a grounding through resistance.
Internal pulse signal Tons charges through CPC pin external capacitor.A.C.-D.C. converter is corresponding different working frequency under different loading conditions, and when not adding built-in noise suppression module, CPC pin voltage exists linear relationship as shown in Figure 6 with load and operating frequency.When adopting built-in noise suppression module; CPC pin voltage will produce a control signal Vau through logic control circuit 500; This control signal Vau obtains the benchmark Vcs_ref of different peak value current comparator 502 through control switch 501; Control signal Vau can be arranged to different high-low levels corresponding underloading and heavily loaded situation respectively, the corresponding underloading of Vau=0 in the present embodiment, otherwise the corresponding heavy duty of Vau=1.
Output current is consistent under the not collinear voltage when realizing that constant current is used; Vcs_ref receives the control of line voltage compensation module simultaneously; This module is through detecting the voltage signal Vaux of former limit conduction period ancillary coil induction, and this voltage signal feeds back to the different Vcs_ref under the not collinear voltage input of Vcs_ref generation branch road realization through the dividing potential drop of resistance R FB1 and resistance R FB2.And the PFM controller of prior art scheme is no matter constant voltage or constant current all have only a constant benchmark Vcs_ref when using; Operating frequency increased along with load variations is linear when constant voltage was worked in this case; 20 can produce audio-frequency noise between the load region among Fig. 6; And constant current when using because of the difference of the primary current rate of rise; Former limit peak current when not collinear voltage was imported after the internal circuit that process is identical was delayed time is inconsistent; The primary current rate of rise was higher than the primary current rate of rise when hanging down the input of line voltage when high line voltage was imported, and the former limit peak current when power transistor really turn-offs is also bigger when high line voltage is imported, output current unanimity under the not collinear voltage in the time of also just can't realizing the constant current application.
Please continue to consult Fig. 5; Control Vref through Vau can be VH or VL corresponding heavy duty of difference and underloading; Obtain the corresponding different respectively former limit peak current of two different Vcs_ref after adopting built-in noise reducing circuit, constant peak current control traditional during the constant voltage application becomes the control of segmentation peak current.VH and VL can be arranged to certain proportionate relationship as 1.5 times; This proportionate relationship has also determined the segmentation Vcs_ref proportionate relationship of segmentation peak current just; During underloading because peak current 1.5 times/one when being reduced to heavy duty; When correspondingly the operating frequency during underloading will promote and control into constant peak current 2.25 times; The corresponding relation of operating frequency and load variations is as shown in Figure 7, is promoted to 1.5 times from zero load to 40% fully loaded interval interior Vcpc, and operating frequency all is promoted to 2.25 times; The segmentation peak current control that built-in noise reducing circuit adopts makes between the load region that is operated in the audiorange and becomes zone 30 more among a small circle by the zone among Fig. 7 20 to the translation of underloading direction, thereby suppresses audio-frequency noise effectively.
Can find out equally that from the computing formula of Vcs_ref Vcs_ref is simultaneously also with V
FBRelevant, the negative pressure of ancillary coil induction primary coil is also passed through the partial pressure value of FB pin outer meeting resistance, the V during conducting of former limit during the conducting of former limit
FBSize reflected the size of the induction of ancillary coil under not collinear voltage primary coil voltage, corresponding V when the input of line voltage is high more
FBVoltage is low more, and is obvious more to the neutralization effect of Vcs_ref, and corresponding Vcs_ref is also more little, and the Vcs_ref during through the not collinear voltage input of adjustment realizes constant peak current, thus the unanimity of output current under the not collinear voltage when guaranteeing that constant current is used.
Fig. 8 is the noise test data of the power switch system of a preferred embodiment based on the utility model, the noise test data in the comparison diagram 1, based on the underloading noise of the power switch system of the utility model embodiment all within testing standard.
The technical scheme of the utility model through a noise reducing circuit is set, promotes than the switching frequency under the underload compared with prior art, has reached the purpose that suppresses audio noise.Because agent structure still is the PFM mode, average conversion efficiency is still higher, satisfies various efficiency standards easily.The power switch of this limit control type; Also increase line voltage compensation circuit etc.; Output current is constant when realizing the input of not collinear voltage, for the constant current application of charger and LED lighting field provides performance guarantee, has not further promoted integrated level on the basis of peripheral components increasing.The A.C.-D.C. converter of employing inverse-excitation type transformer device structure disclosed in the utility model utilizes constant current output to replace overcurrent protection, and the EMI simplicity of design.The few reliability of this A.C.-D.C. converter number of elements is high, has complied with small sizes such as charger, LED, appliance network, application trend cheaply.
The preferred embodiment of the just the utility model described in this specification, above embodiment is only in order to the technical scheme of explanation the utility model but not to the restriction of the utility model.All those skilled in the art according to the design of the utility model through the available technical scheme of logical analysis, reasoning, or a limited experiment, all should be within the scope of the utility model.
Claims (10)
1. the power switch of a former limit control type comprises pulse frequency modulated controller and power transistor, it is characterized in that, said pulse frequency modulated controller comprises noise suppression module, line voltage compensation module and peak current control module; Said noise suppression module is connected with said peak current control module to form a segmentation peak current; Output current unanimity under not collinear voltage when said line voltage compensation module is used in order to the realization constant current.
2. power switch as claimed in claim 1 is characterized in that, said peak current control module is a peak current comparator, and said peak current comparator is connected with the base stage of said power transistor.
3. power switch as claimed in claim 1; It is characterized in that; Said noise suppression module comprises that the logic control circuit that is connected with the CPC pin is used to produce a control signal, and said control signal is connected with said peak current control module through a control switch.
4. power switch as claimed in claim 3 is characterized in that, also comprises one first resistance between said control switch and the said peak current control module.
5. power switch as claimed in claim 1 is characterized in that, said line voltage compensation module comprises first outer meeting resistance and second outer meeting resistance that is connected with the FB pin, and said first outer meeting resistance is connected with the auxiliary winding of second outer meeting resistance and transformer.
6. power switch as claimed in claim 5 is characterized in that, said line voltage compensation module is connected with said peak current control module through second resistance; Said FB pin is connected with the 3rd resistance, said the 3rd grounding through resistance.
7. power switch as claimed in claim 1 is characterized in that, said power transistor is double pole triode or FET.
8. an A.C.-D.C. converter is characterized in that, comprising:
Power supply;
Transformer has the main winding that is coupled to said transformer, and said switch is used for receiving control signal to open or to cut out the electric current of main winding;
The output rectifier diode;
Like each described power switch of claim 1 to 7.
9. A.C.-D.C. converter as claimed in claim 8; It is characterized in that; Said output rectifier diode conduction period; To obtain output voltage information, said output voltage information is by external first feedback resistance of the FB pin of said power switch and the sampling of second feedback resistance through induction secondary coil voltage for the auxiliary winding of said transformation.
10. A.C.-D.C. converter as claimed in claim 8 is characterized in that, said A.C.-D.C. converter also comprises a RCD absorption circuit, the peak voltage that produces because of transformer leakage inductance and distributed capacitance when turn-offing in order to the absorbed power transistor.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011202903940U CN202168002U (en) | 2011-08-11 | 2011-08-11 | Primary-side control type power switch and alternating current-direct current converter |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011202903940U CN202168002U (en) | 2011-08-11 | 2011-08-11 | Primary-side control type power switch and alternating current-direct current converter |
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| CN202168002U true CN202168002U (en) | 2012-03-14 |
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| CN2011202903940U Expired - Lifetime CN202168002U (en) | 2011-08-11 | 2011-08-11 | Primary-side control type power switch and alternating current-direct current converter |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103427623A (en) * | 2012-05-25 | 2013-12-04 | 弗莱克斯电子有限责任公司 | Power converter with noise immunity |
| CN103780096A (en) * | 2014-01-24 | 2014-05-07 | 上海新进半导体制造有限公司 | Switch power source, control chip and method for voltage compensation for charging cable |
| CN104506043A (en) * | 2015-01-07 | 2015-04-08 | 上海新进半导体制造有限公司 | Noise control method and circuit and switch power of power converter |
| CN106374742A (en) * | 2016-11-08 | 2017-02-01 | 上海贝岭股份有限公司 | Switching power supply output frequency regulating circuit |
| CN106487248A (en) * | 2016-10-10 | 2017-03-08 | 上海晶丰明源半导体有限公司 | Controller, Switching Power Supply and line voltage compensation method |
| CN107276402A (en) * | 2016-04-08 | 2017-10-20 | 无锡市晶源微电子有限公司 | Flyback power supply converter |
| CN110190735A (en) * | 2019-06-21 | 2019-08-30 | 杰华特微电子（杭州）有限公司 | Switching Power Supply |
| CN111181380A (en) * | 2020-02-25 | 2020-05-19 | 苏州力生美半导体有限公司 | Control circuit and method for suppressing audio noise |
-
2011
- 2011-08-11 CN CN2011202903940U patent/CN202168002U/en not_active Expired - Lifetime
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103427623A (en) * | 2012-05-25 | 2013-12-04 | 弗莱克斯电子有限责任公司 | Power converter with noise immunity |
| CN103780096A (en) * | 2014-01-24 | 2014-05-07 | 上海新进半导体制造有限公司 | Switch power source, control chip and method for voltage compensation for charging cable |
| CN104506043A (en) * | 2015-01-07 | 2015-04-08 | 上海新进半导体制造有限公司 | Noise control method and circuit and switch power of power converter |
| CN104506043B (en) * | 2015-01-07 | 2017-09-01 | 上海新进半导体制造有限公司 | Noise control method, circuit and the Switching Power Supply of a kind of power supply changeover device |
| CN107276402A (en) * | 2016-04-08 | 2017-10-20 | 无锡市晶源微电子有限公司 | Flyback power supply converter |
| CN107276402B (en) * | 2016-04-08 | 2023-09-08 | 无锡市晶源微电子股份有限公司 | Flyback power converter |
| CN106487248A (en) * | 2016-10-10 | 2017-03-08 | 上海晶丰明源半导体有限公司 | Controller, Switching Power Supply and line voltage compensation method |
| CN106487248B (en) * | 2016-10-10 | 2019-01-29 | 上海晶丰明源半导体股份有限公司 | Controller, Switching Power Supply and line voltage compensation method |
| CN106374742A (en) * | 2016-11-08 | 2017-02-01 | 上海贝岭股份有限公司 | Switching power supply output frequency regulating circuit |
| CN106374742B (en) * | 2016-11-08 | 2019-04-09 | 上海贝岭股份有限公司 | Switching Power Supply output frequency adjusts circuit |
| CN110190735A (en) * | 2019-06-21 | 2019-08-30 | 杰华特微电子（杭州）有限公司 | Switching Power Supply |
| CN111181380A (en) * | 2020-02-25 | 2020-05-19 | 苏州力生美半导体有限公司 | Control circuit and method for suppressing audio noise |
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Effective date of registration: 20210224 Address after: No. 1600, Zixing Road, Minhang District, Shanghai 200241 Patentee after: BCD (SHANGHAI) MICRO-ELECTRONICS Ltd. Address before: 200241 no.800, Yishan Road, Xuhui District, Shanghai Patentee before: BCD Semiconductor Manufacturing Ltd. |
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| CX01 | Expiry of patent term | ||
| CX01 | Expiry of patent term |
Granted publication date: 20120314 |