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Dual Switch Flyback Solution

Solution for High Efficiency & Low Standby Power to meet 2013 EuP

Computing Product LinePower Conversion TaiwanFairchild Semiconductor

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Dual Switch QR Solution

VDD

RES

AGNDGND

LPC

VOUT

Lm

IDS ISR

R1

R2 R4

R3

n:1

GATE

8

3 5

7

64

Q2

Q1

IDS

Q1

FAN7382FAN6920

FAN6204

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

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Basic Operation of Dual Switch Flyback

Vo

+

-Vin

+

-

Vin+

-

Vin

+

-

i Lm

Vo

+

-Vin

+

-

iLmnVo

-

+

+Vds-low

-

+Vds-high

-

Phase 2

vin

nvo

vin+nvo

Vds1 , Vds2

Q1 , Q2 gate

iLm

22

2

vin

id1, id2

Phase 1 Phase 3 Phase 4

Phase 1: Q1&Q2 On

Phase 2: Q1&Q2 Off, D1, D2 on

Phase 3&4: Q1&Q2 off, D1&D2 off

Vo

+

-Vin

+

-

iLk

iLmnVo

-

+

+Vds-low

-

+Vds-high

-

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Benefit of Dual Switch Flyback (1)Snubber and Leakage Inductance Loss Improved

Vo

VIN

Np:Ns

R C

ID

IDS

VDS

Vo

+

-Vin

+

-

iLk

iLmnVo

-

+

+Vds-low

-

+Vds-high

-

No snubber loss and heat problem

Single Flyback

Dual Flyback

Leakage inductance is recycled into bulk capacitor

iLK

iDS

Up to 70% of leakage inductance can be recycled

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Benefit of Dual Switch Flyback (2)Low MOSFET Vds and Near ZVS switching

VIN

Vo×

Vds

Vo× n

n

VIN /2Vo /

2

×

)( nVIN

Vo×

Vds

2n

/

)(

Vds of Single Flyback Vds of Dual Flyback

Vds = Vin + n*Vo + Spike Vds= Vin/2Spike 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

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Benefit of Dual Switch Flyback (3)Low VDS of SR MOS for secondary conduction loss

VO U T

VDS

VIN /n

VDD

RES

AGNDGND

LPC

VOUT

Lm

ISR

R1

R2 R4

R3

n:1

GATE

8

3 5

7

64

Q2

FAN6204

Benefit of high turn ration n to SR MOSFET

Example: Vin = 420V, Vo = 12V, n= 12

VDS = 420V/12 + 12V = 47V

Could choose 60V or 75V SR MOSFET

VI N

/ n + VO U T

VDS of SR MOS is : Vin/n + Vout

Large n Lower VDS Lower MOS Ron in lower price cost & efficiency

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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

150VRMS VAC

300V

390V

180VRMS

PFC Vo

3

COINV

PFC Vo

R1

R2RANGE

Debounce100ms

1

13

2.45V/2.1V

VIN

R3

AC line

Multi-vector Error Amplifier

R4

R5CVIN

2.5V

1.2V/1V Debounce100ms

Brownout

M1

When AC > 180V M1 off PFC Vo = 2.5V x (R1+R2)/R2When AC < 150V M1 on R2//R3 PFC Vo= 2.5V x (R1+R2//R3))/(R2//R3)

FAN6920 Block Diagram

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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

Switching frequency (Hz)

VFB

1.2V 2.1V

fs,min

fs,max

20k

fs,g

VFB,max

2k

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

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Benefit of Dual Switch Flyback (6)Power Saving

• Dual Switch Flyback Could Meet < 0.5W @ 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

VAC Po = 0 W Po= 0.25W

115V 0.186W 0.482W

230V 0.195W 0.486W

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Target Application

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

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Dual-switch Flyback Schematic

+

-

VO

VAC

NTC

NBOOST

NCZD

RCZD

RVIN1

RVIN2

CVIN

CDD

CINF1

CINF2

RG1

RCS1

RPFC1

RPFC2

CCOMP

CO.PFC

RHV

RDET1

RDET2

RO1

RO2

RF CF

KA431

RBIAS

RRT

CRT

CFB

NP

NS

NA

RCS2

BCM Boost PFC Dual-Switch Quasi Resonant Flyback

VCC1

2

3

4

8

7

6

5

HIN

LIN

COM

VB

HO

VS

LO

FAN7382

RANGE1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9

COMP

INV

CSPFC

CSPWM

OPFC

VDD

OPWM

HV

NC

ZCD

VIN

RT

FB

DET

GND

FAN6920

NB

VDD

RES

AGNDGND

LPCFAN6204

GATE

8

3 5

7

64

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Solution Comparison

Dual Switch QR Flyback LLC Note

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 response Poor line transient response Inherent characteristic of topology

Good load transient response

Poor load transient response Inherent characteristic of topology

Power Saving <0.3W, <0.5W, LLC couldn’t allow PFC turn off at light load.

Design Easiness

Easy Difficult Resonant L & C control to prevent ZVS fail

Manufacture Easiness

Easy Difficult Resonant L & C control to prevent ZVS fail

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Key Parts Comparison

MOSFET 3 (PFC and dual switch) 3 (PFC and LLC)

Transformer1 for PFC1 for D2D

1 for PFC 1 for D2D 1 for resonant L & C

IC FAN6920MR+FAN7382 (HVIC)

CRM PFC+ LLC controller

SRIC FAN6204 2 SR controller

MOSFET 1 2 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~200W 100W~500W

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Dual Switch Flyback vs. LLC

Efficiency: test board 90W/19V

No load

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Slim Type 19V/ 90W Dual Switch FlybackEfficiency Test Result

22.5W 45W 67.5W 90W

115VAC 89.48% 90.54% 90.40% 89.61%

230VAC 91.24% 90.04% 90.86% 90.88%

Efficiency (18 AWG 1.2m wire include):

60mm95mm16.5mm

No Load Power Consumption:

VAC

(RM S) PI N

(W )

90 0.190

115 0.186

230 0.195

264 0.210Input Power @ 0.25WVAC (RMS) PIN(W)

115 0.482

230 0.486

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19V/180W Dual FlybackFAN6204 + FDP032N08

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130W/19V AIO power

Spec: PIN<0.5W 2013 EUP

Input Power @ 0.25W

Efficiency 20%26W

50%65W

100%130W

3 pointAVG.

115Vac/60Hz 89.29% 92.15% 92.32% 91.25%

230Vac /50Hz 91.65% 92.15% 93.59% 92.56%

100mm 145mm

VAC (RMS) PIN(W)

115 0.478

230 0.482

VAC (RMS) PIN(W)

90 0.19

115 0.186

230 0.195

264 0.21

Input Power @ no load

AIO 130W

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200W/19V AIO Power

Efficiency 20%40W

50%100W

100%200W

3 pointAVG.

115Vac/60Hz 90.01% 91.62% 90.76% 90.79%

230Vac /50Hz 92.16% 91.76% 92.60% 92.17%

Output Power @ 0.5W

VAC (RMS) PIN(W)

115 0.762

230 0.781

VAC (RMS) PIN(W)

90 0.168

115 0.183

230 0.206

264 0.223

Output Power @ no load Output Power @ 0.25W

VAC (RMS) PIN(W)

115 0.484

230 0.487

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Example Circuit (19V/90W)

C40.33μ /450V

C50.33μ /450V

+C7

47μ/450V

1

23

Q4FQI13N50C

2 1

D1ES3J

D14LL4148

R46 51

1

23

Q2FQI13N50C

YC/102P/250V

R104.7M±1%

D13LL4148

R47 51

1

23

Q1FQI13N50C

21

D4ES1H

21

D2ES1JH

R114.7M±1%

R124.7M±1%

VSPFC VSPWM

R30154K±1%

R2278.7K±1%

R94.7M±1%

AC

AC -

+

BD1DF08S PFC_VO

D10RS1D

C27224P

C21NC

C25105P

R24220

C24221P

C20102P

RANGE1

COMP2

INV3

CSPFC4

CSPWM5

OPFC6

VDD7

OPWM8

FB 11

RT 12

VIN 13

ZCD 14

N.C. 15

HV 16

GND 9

DET 10

U2

FAN6920

C29102P

R2647.5K

C23471P

R23220

VSPFC

R27 560

C26473P

OPFC

VSPWM

VS 6

LO 5

LIN3

HIN2

VB 8VCC1

COM4

HO 7

U3FAN7382

C30225P

VB

C31104P

PFC_VO

TR1NTC/100K

R313.6K

R747K

R847K

+ C1533μ /50V

21

D9RS1D

R298.2K±1%

R2847.5K±1%

C28NC

12

CN1

CN/2pin AC inlet

MO

V1

MO

V/U

07 470

C1XC/0.47u/250VL

F1

F/4A/250V

R2

1.5M/1206

R1

1.5M/1206

+

C8820μ /25V

VO+

VO+1

VO-1

R160R15 R17

0R27

L2

DET1

U4LTV357A

C33103P

R51330

R521.5K

R5068K, 1%

R5310K, 1%

R4910K

AK

RU5KA431SAMF2TF

VO+

VO

2 1

D15ES1JH

HG

HG

VBO

LG

LGOPWM

OPWMAUX

D7S1M

D6S1M

PFCZCD

PFCZCD

FBPWM

FBPWM

VDD

VS

VS

VBO

AUX

R5 100R4 100R3 100

C17102P/100V

R219.1K±1%

R20220K±1%

R4811.3K±1%

R1847K±1%

C32NC

VO

C19104P

VDD

C18104P/50V

R6249K

R25 NC

C22474P

12

56

411

TX1

+C6

47μ/450V

GATE3

PGND 4AGND 6

LPC 8

VDD5

RP/RES7

U1FAN6204/5

1

2 3

Q5FDB031N08

21

D11NC

R19R/0R

SRDET

SRDET

VO1

VDD

C10

YC/102P/250V

+

C9820μ /25V

+ C1633uF/50V

VDD

C11YC/102P/250V

C3NC

C2NC

AC

AC -

+

BD2DF08S

VBO1

L4

S047

VO

21

ZD118V/0.5W

21

ZD218V/0.5W

VLD

OPWMR45NC

OPFC

2 1

D8LL4148

R1351

2

13

Q32N2907

R14

100

R15NC

PFC_GATE

D12LL4148

84

35

6 1

7

2

11

TX2

2 1

L3A220μ /DR127

2 1D5

SS16

PFC_GATE

L1

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