Design Idea DI-93

32 W Continuous (81 W Peak) Supply

www.powerint.com

Figure 1. 32 W (Continuous), 81 W (Peak) Power Supply Using PKS606Y.

DI-93

June 2006

Application

Device

Power Output

Input Voltage

Output Voltage

Topology

Inkjet Printer

PKS606Y

32 W / 81 W pk

90-265 VAC

30 V

Flyback

Design Highlights

• Delivers up to 2.5 times the full load power for 50 ms

• Uses a small EE25 core transformer

• Meets EPS active-mode efficiency specifications

• No-load input power <200 mW at 265 VAC

• High standby and sleep mode efficiency: >66% and 75%

Operation

Thissupplyisconfiguredasaflybackconverter. TheON/OFF

controller integrated within the PeakSwitch IC (U1) has an

internal oscillator frequency of 277 kHz. Feedback from the

outputcausesthecontrollertoskipMOSFETswitchingcycles

to regulate the output voltage. The skipping of switching

cycles adjusts the converter s effective switching frequency

(F

32 W continuously, the F

demands peak power from the supply, the controller skips

fewer switching cycles, raising the F

supply to deliver peak power pulses of up to 81 W (for up to

50 ms), while keeping the output voltage in regulation.

PeakSwitch

has three functions that interact with each other:

auto-restart, conditional latching shutdown and smart AC line

sense. Components D5, C7, R5 and R6 enable the smart AC

line sense and the under-voltage lockout (UVLO) functions.

When U1 does not skip any switching cycles for >30 ms, the

auto-restart function activates. If AC line voltage is absent or

insufficient for normal operation when auto-restart activates,

latching shutdown is disabled, and normal operation will

resume after the AC line voltage is restored. If AC line voltage

is sufficient for normal operation when auto-restart activates,

latching shutdown is enabled, andAC power must be removed

and reapplied to reset the latch. The low value of C7 enables

latch reset to occur quickly, once AC is removed.

The smart AC line sense components also enable the UVLO

function. UVLO inhibits MOSFET switching until current

into the EN/UV pin is >25 µA. Resistor R16 supplies the

1 µA threshold current that activates the UVLO and AC sense

features, keeping those functions activated during brownouts

and line sags.

T1

EE25

J1

L

PE

N

30 V @

1.07 A Cont.

2.7 A Peak

RTN

D5

1N4007

D6

FR106

D10

UF4003

D8

STPS3150

D9

1N4148

D7

1N4148

U2

PC817X4

Q2

FS202DA

J3

PCB Term 18 AWG

RTN Connected to PE via Flying Lead

Q1

2N3906

D1-D4

1N4007

L1

5.3 mH

L2

5.3

µH

R2

1.3 M

Ω

R1

1.3 M

Ω

R15

2.2

Ω

R4

22

Ω

1/2 W

R3

10 k

Ω

1/2 W

R5

2.2 M

Ω

R6

2.4 M

Ω

R16

2.7 M

Ω

R7

4.7 k

Ω

R12

1 k

Ω

R13

1 k

Ω

R14

100

Ω

R11

3 k

Ω

R10

1.5 k

Ω

R9

0.33

Ω

2 W

R8

68

Ω

1/2 W

C3

680 nF

X1

C1-C2

100 pF

250 VAC

C17

4.7 nF

1 kV

C6

47

µF

35 V

C15

100 nF

50 V

C16

100 nF

C12

330

µF

50 V

C10

1 nF

250 VAC

C11

330 pF

U1

PKS606Y

C13

47

µF

16 V

C14

220 nF

50 V

C7

100 nF

400 V

C8

220 nF

50 V

C5

2.2 nF

1 kV

VR1

1N4764A

100 V

VR2

1N5255B

28 V

VR3

1N5258B

36 V

1

9,10

7,8

4

5

3

2

C4

150

µF

400 V

F1

3.15 A

RT1

10

Ω

PI-4170-060706

PeakSwitch

C19

1 nF, 250 VAC

D

S

EN/UV

BP

GND