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Design a Champion AC Adapter

CM6805/CM6806/CM6903/CM6201. Design a Champion AC Adapter. Jeffrey H. Hwang. CM6805/CM6806/CM6903/CM6201. Two Sources:. Champion and FairChild. CM6805/CM6806/CM6903/CM6201. Cost Reduction by $0.30 to $0.20. With CM6805, CM6806, CM6903 vs. CRM +PWM. CM6805/CM6806/CM6903/CM6201.

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Design a Champion AC Adapter

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  1. CM6805/CM6806/CM6903/CM6201 Design a Champion AC Adapter Jeffrey H. Hwang

  2. CM6805/CM6806/CM6903/CM6201 Two Sources: Champion and FairChild

  3. CM6805/CM6806/CM6903/CM6201 Cost Reduction by $0.30 to $0.20 With CM6805, CM6806, CM6903 vs. CRM +PWM

  4. CM6805/CM6806/CM6903/CM6201 If the Microprocessor Is the brain of the system, then the Power Supply is the heart.

  5. CM6805/CM6806/CM6903/CM6201 High Density AC Adapter The Challenge: High Efficiency at Low Line (90VAC)

  6. CM6805/CM6806/CM6903/CM6201 Typical Power vs. Efficiency

  7. CM6805/CM6806/CM6903/CM6201 High Density AC Adapter

  8. CM6805/CM6806/CM6903/CM6201 How to increase the Efficiency? (Rule of Thumb) • Full Load due to Conduction Loss = I x I x R: • Spend more money to reduce R such as reduce Rdson of Mosfet • Reduce I by increasing VIN • Light Load due to Switching Loss = fsw x C x V x V: • Reduce C • Reduce V = ZVS • Reduce fsw => Green Mode

  9. Full Load Condition Analysis Failure Rate Vs. Temperature

  10. Full Load Condition Analysis It is desired to have a uniform Surface Temperature for Convection and Radiation By Proper Layout/Package/Enclosure

  11. Full Load Condition Analysis Maximum Power Dissipation vs. Shape By Proper Layout/Package/Enclosure

  12. Full Load Condition Analysis The Maximum Output Power vs. Shape h , Po h , Po By Proper Layout/Package/Enclosure

  13. Full Load Condition Analysis Use the better Core Shape Due to the smooth surface, it has the better heat convection By Proper Layout/Package/Enclosure

  14. Full Load Condition Analysis A Good AC Adapter Layout Keep the temperature uniform through out the board By Proper Layout/Package/Enclosure

  15. Full Load Condition Analysis 36W Fly Back AC Adapter Experimental Result FLYBACK Design a Flyback Converter

  16. Full Load Condition Analysis 36W Fly Back AC Adapter Experimental Result η~85.6% @ 90VAC with full load FLYBACK Design a Flyback Converter

  17. Full Load Condition Analysis How To Improve Flyback Transformer Power Loss? FLYBACK • Reduce the n, Turn Ratio to reduce the Secondary Peak Current • When n ,Ip ,Is , D , Lm , Ls , then Maximum Secondary Voltage . • When n , Ip , Is , D is , Lm , Ls ,then Maximum Secondary Voltage . • 2. Increase the Flyback input voltage • 3. Use the better RM core instead of EPC core Design Flyback Converter

  18. Full Load Condition Analysis How To Improve Flyback Transformer Power Loss? FLYBACK Design Flyback Converter

  19. Full Load Condition Analysis How To Reduce Flyback Diode Rectifier Power Loss? FLYBACK • Increase the Flyback input Voltage • Use SR, Synchronous Rectification + DCM • Reduce the secondary current by reducing n, the turn ratio of Transformer(This will increase Mosfet Loss.) Design a Flyback Converter

  20. Full Load Condition Analysis How To Reduce Flyback Diode Rectifier Power Loss? FLYBACK Use a Synchronous Rectifier Design a Flyback Converter

  21. Full Load Condition Analysis How To Reduce Flyback Diode Rectifier Power Loss? FLYBACK CCM + Synchronous Rectification has the lower efficiency due to Trr, body diode recovery issue Design a Flyback Converter

  22. Full Load Condition Analysis How To Reduce Flyback Diode Rectifier Power Loss? FLYBACK CCM + Synchronous Rectification has Trr, body diode recovery issue Design a Flyback Converter

  23. Full Load Condition Analysis How To Reduce Flyback Diode Rectifier Power Loss? FLYBACK CCM + Synchronous Rectification has Trr, body diode recovery issue Design a Flyback Converter

  24. Full Load Condition Analysis How To Reduce Flyback Diode Rectifier Power Loss? DCM Efficiency vs. Input voltage FLYBACK 86%, Efficiency @ 200V, Vin CCM + Synchronous Rectification has Trr, body diode recovery issue Design a Flyback Converter

  25. Full Load Condition Analysis How To Reduce Flyback Diode Rectifier Power Loss? FLYBACK • Solution: • Use DCM + SR, Synchronous Rectifier + Vin >200V + Reduce n CCM + Synchronous Rectification has Trr, body diode recovery issue Design a Flyback Converter

  26. Full Load Condition Analysis How To Reduce Flyback Diode Rectifier Power Loss? Solution: Use DCM + SR, Synchronous Rectifier + Vin > 200V + Reduce n FLYBACK CCM + Synchronous Rectification has Trr, body diode recovery issue Design a Flyback Converter

  27. Full Load Condition Analysis How To Improve Flyback MOSFET Power Loss? FLYBACK • Increase the Flyback input voltage so conduction loss can be reduced due to D drops. • Using DCM to prevent the Trr, diode reverse current issue • Use a lower Rdson Mosfet • Use ZVS Design Flyback Converter

  28. Full Load Condition Analysis • Conventional Flyback Converter: FLYBACK LC tank’s C is due to S1 and It is very small, so Ring frequency (resonant frequency) is high. Design Flyback Converter

  29. Full Load Condition Analysis • Conventional Flyback Converter: resonant f is high so it is difficult to control (manufacture control) it. FLYBACK Ip Vds, S1 The Energy Stored in leakage inductor is wasted in the ringing. Design Flyback Converter

  30. Full Load Condition Analysis • ZVS Flyback Converter: Active Clamp FLYBACK LC tank’s C is due to Cclamp~1uF and It is relative big, so Ring frequency (resonant frequency) is lower. Design Flyback Converter

  31. Full Load Condition Analysis • ZVS Flyback Converter: Active Clamp FLYBACK No Ring and ZVS The energy is stored in the core; release to the input Design Flyback Converter

  32. Full Load Condition Analysis • ZVS Flyback Converter: Active Clamp FLYBACK No Ring and ZVS Design Flyback Converter

  33. Full Load Condition Analysis • ZVS Flyback Converter: Active Clamp 4.5% Improvement FLYBACK Design Flyback Converter

  34. Full Load Condition Analysis • ZVS Flyback Converter: Active Clamp • 4.5% Improvement due to: • Energy in leakage L and Snubber is saved (Clamped) • Energy in Vds-parasitic capacitor is saved (ZVS) FLYBACK • However, it is expensive: • It needs a high side driver, an extra high side Mosfet • and a simple control circuit • Can we do it without additional cost? Design Flyback Converter

  35. Full Load Condition Analysis • ZVS Flyback: • Secondary Synchronous Rectifier • with • CM6201 (smart driver) FLYBACK LC tank’s C becomes to Co/(n x n)~25uF to 50uF and It is big, so Ring frequency (resonant frequency) is very low. Design Flyback Converter

  36. Full Load Condition Analysis • ZVS Flyback: • Secondary Synchronous Rectifier • with • CM6201 (smart driver) FLYBACK • Benefits: • It does not need high side driver and high side mosfet • Synchronous Rectification at DCM • Fly back full load Efficiency is increased • from • ~86% to~90% at Flyback input=200V Design Flyback Converter

  37. Full Load Condition Analysis Summary: designing Flyback Converter @ full load & Vin=200V • Without additional cost: Efficiency~87.5% @Full load • Vin >= 200V (with PFC-PWM combo CM6805/06/CM6903)…. Δη =3% • n, turn ratio = 5 or 6….Reduce Is peak current • Full load at DCM but approach to CCM….remove Trr • ZVS by controlling LC variation….Δη=1.5% • With additional cost: Efficiency~93% @Full load • Secondary Synchronous Rectifier +ZVS: (CM6201) • # Total additional Δ$~ $0.3 at high volume…. Δη=2% • RM core • #Δ$ ~$0.2 at high volume….. Δη=1.5% • ZVS Active Clamp at primary side….Δ$ ~$0.8 with Δη=2% FLYBACK Without the proper design, efficiency could be below 80%. Design Flyback Converter

  38. Full Load Condition Analysis Choose Follower Boost Inductor CM6805 family vs. CRM, 6561 • L ↑, Efficiency ↑ • For CRM, 6561, it cannot increase boost inductance. • L↑, frequency needs to go lower and it can go below 20Khz • Ton=L / Rload; for a given load, Ton is a constant • L ~ 471uH cannot go higher for the Po = 100W • Ipeak = Iin Peak x 2 (I x I x R is big; efficiency is poor!) • At high line and light load, frequency can go above 400Khz (EMI issue is severe.) • For CM6805/CM6806/CM6903 fixed switching frequency=67.5Khz, • Lcm6805 family ~ Lcrm (67.5khz) x 5 (Optimal Inductance Value) • Lcrm ~ 209uH @ 90VAC • Loptimal = 1050 uH @ 100W to L= 698 uH @150W • L ↑, Efficiency ↑ • Both the cost of Boost Mos and Boost Rectifier can be reduced • Efficiency (CCM) – Efficiency (CRM) > 3% (total system) Design a Follower Boost PFC

  39. Full Load Condition Analysis Boost Power Dissipation Breakdown η=91.37%, Vin=90VAC, Po=1KW Boost PFC 2% 1% MOSFET MOSFET Boost 400V Cap MOSFET Design a Follower Boost PFC

  40. Full Load Condition Analysis η=91.37%, Vin=90VAC, Po=1KW Boost PFC Design a Follower Boost PFC

  41. Full Load Condition Analysis Power Dissipation in Boost Diode Boost PFC Design a Follower Boost PFC

  42. Full Load Condition Analysis Power Dissipation in Boost Mosfet Boost PFC Dominated One Design a Follower Boost PFC

  43. Full Load Condition Analysis Boost PFC 4.5% Improvement Design a Follower Boost PFC

  44. Full Load Condition Analysis PFC Boost with 380V only Boost PFC Design a Follower Boost PFC

  45. Full Load Condition Analysis Continuous Boost Follower 4.5% Improvement….cost~$0.03 Boost PFC Added Circuit VlineDC needs to be closed to Dc and > = 5V. Design a Follower Boost PFC

  46. Full Load Condition Analysis Two Level Boost Follower (Q1 on, 200V @ low line and Q1 off 380V @ high line) 4.0% Improvement….cost~$0.02 Boost PFC Added Circuit VlineDC @ high line will turn off Q1 and @ low line will turn on Q1. Design a Follower Boost PFC

  47. Full Load Condition Analysis Two Level Boost Follower or Continuous Boost Follower Boost PFC 4.0% to 4.5% Efficiency Improvement….cost~$0.02 to $0.03 Design a Follower Boost PFC

  48. Full Load Condition Analysis PFC Boost Rectifier Trr issue Boost PFC Design a Follower Boost PFC

  49. Full Load Condition Analysis Use SiC to solve PFC Boost Rectifier Trr issue Boost PFC Δη~1% Δ$~$1.0 Design a Follower Boost PFC

  50. Full Load Condition Analysis SiC will help if the frequency is high. Boost PFC Design a Follower Boost PFC

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