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Www.fairchildsemi.com 1 Dual Switch Flyback Solution Solution for High Efficiency & Low Standby Power to meet 2013 EuP Computing Product Line Power Conversion.

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Presentation on theme: "Www.fairchildsemi.com 1 Dual Switch Flyback Solution Solution for High Efficiency & Low Standby Power to meet 2013 EuP Computing Product Line Power Conversion."— Presentation transcript:

1 1 Dual Switch Flyback Solution Solution for High Efficiency & Low Standby Power to meet 2013 EuP Computing Product Line Power Conversion Taiwan Fairchild Semiconductor

2 2 Dual Switch QR Solution Enabled by FAN6920 : CRM PFC + QR Controller Combo IC FAN7382 : HVIC FAN6204 : Syn. Rectifier IC

3 3 Basic Operation of Dual Switch Flyback Phase 1: Q1&Q2 On Phase 2: Q1&Q2 Off, D1, D2 on Phase 3&4: Q1&Q2 off, D1&D2 off

4 4 Benefit of Dual Switch Flyback (1) Snubber and Leakage Inductance Loss Improved No snubber loss and heat problem Single Flyback Dual Flyback Leakage inductance is recycled into bulk capacitor i LK i DS Up to 70% of leakage inductance can be recycled

5 5 Benefit of Dual Switch Flyback (2) Low MOSFET Vds and Near ZVS switching Vds of Single Flyback Vds of Dual Flyback Vds = Vin + n*Vo + Spike Vds= Vin/2 Spike is clamped by two recycle diodes, stress shared by two MOS Low MOSFET Drain Source Voltage  Good reliability Allow large n design  Near ZVS Switching  Low switching loss Larger switching loss Near ZVS Switching

6 6 Benefit of Dual Switch Flyback (3) Low V DS of SR MOS for secondary conduction loss Benefit of high turn ration n to SR MOSFET Example: Vin = 420V, Vo = 12V, n= 12  V DS = 420V/ V = 47V  Could choose 60V or 75V SR MOSFET V DS of SR MOS is : Vin/n + Vout Large n  Lower V DS  Lower MOS Ron in lower price  cost & efficiency

7 7 Benefit of Dual Switch Flyback (4) Built in two level PFC output for low line efficiency Two Level PFC output to improve low line efficiency M1 When AC > 180V  M1 off  PFC Vo = 2.5V x (R1+R2)/R2 When AC < 150V  M1 on  R2//R3  PFC Vo= 2.5V x (R1+R2//R3))/(R2//R3) FAN6920 Block Diagram

8 8 Benefit of Dual Switch Flyback (5) Deep extended valley switch for light load efficiency Deep extended valley switch ( up to 12th valley) to allow low operating frequency in light load  Improved light load efficiency First valley detect 5th valley detect 12th valley detect QR Operation without extended valley switch Other IC: QR Operation with extended valley ( up to 4th valley) Load ↓  Freq ↑  Poor light load efficiency FAN6920 Deep extended valley switch Freq. nearly constant

9 9 Benefit of Dual Switch Flyback (6) Power Saving Dual Switch Flyback Could Meet < 0.25W ( 2013 EuP) PFC Stage: High line/light load  Turn off PFC Low line/light load  burst mode QR Stage: enter into burst mode when light load No snubber loss SR Stage: Turn off SR when light load Power Saving Load V AC Po = 0 WPo= 0.25W 115V0.186W0.482W 230V0.195W0.486W

10 10 Target Application For Power Range from 75W ~200W All in One PC Power LED TV Notebook Adapter Game Console LED Lighting

11 11 Dual-switch Flyback Schematic

12 12 Solution Comparison Dual Switch QR FlybackLLCNote Efficiency D2D stage : Nearly ZVS switching D2D stage: ZVS switching PFC stage: Better low line efficiency by two level PFC output PFC stage: Poor low line efficiency due to high PFC output LLC could allow only narrow input voltage range Light load (~20%) : Higher efficiency due to slow freq. to reduce switching loss Light load (~20%) : Low efficiency due to high frequency. FAN6920 could do up to 12th valley detection for slow frequency Dynamic Good line transient responsePoor line transient responseInherent characteristic of topology Good load transient response Poor load transient responseInherent characteristic of topology Power Saving<0.3W,<0.5W,LLC couldn’t allow PFC turn off at light load. Design Easiness EasyDifficultResonant L & C control to prevent ZVS fail Manufacture Easiness EasyDifficultResonant L & C control to prevent ZVS fail

13 13 Key Parts Comparison MOSFET 3 (PFC and dual switch)3 (PFC and LLC) Transformer 1 for PFC 1 for D2D 1 for PFC 1 for D2D 1 for resonant L & C IC FAN6920MR+FAN7382 (HVIC) CRM PFC+ LLC controller SR IC FAN62042 SR controller MOSFET 12 MOSFETs Cost -Lower transformer cost -Lower MOSFET cost -One SR MOSFET needed -Higher transformer cost -Might need additional resonant T’mer -Two SR MOSFET needed -Might need additional std by stage for power saving Power Range 75W~200W100W~500W

14 14 Dual Switch Flyback vs. LLC Efficiency: test board 90W/19V No load

15 15 Slim Type 19V/ 90W Dual Switch Flyback Efficiency Test Result 22.5W45W67.5W90W 115VAC89.48%90.54%90.40%89.61% 230VAC91.24%90.04%90.86%90.88% Efficiency (18 AWG 1.2m wire include): 60mm 95mm 16.5mm No Load Power Consumption: Input 0.25W V AC (RMS)P IN (W)

16 V/180W Dual Flyback FAN FDP032N08

17 W/19V AIO power Spec: P IN <0.5W 2013 EUP Input 0.25W Efficiency 20% 26W 50% 65W 100% 130W 3 point AVG. 115Vac/60Hz89.29%92.15%92.32%91.25% 230Vac /50Hz91.65%92.15%93.59%92.56% 100mm 145mm V AC (RMS)P IN (W) V AC (RMS)P IN (W) Input no load AIO 130W

18 W/19V AIO Power Efficiency 20% 40W 50% 100W 100% 200W 3 point AVG. 115Vac/60Hz90.01%91.62%90.76%90.79% 230Vac /50Hz92.16%91.76%92.60%92.17% Output 0.5W V AC (RMS)P IN (W) V AC (RMS)P IN (W) Output no load Output 0.25W V AC (RMS)P IN (W)

19 19 Example Circuit (19V/90W)

20 20 Follow us on twitter.com/fairchildSemitwitter.com/fairchildSemi View product and company videos, listen to podcasts and comment on our Visit us on


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