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SS8028

minimize the output ripple voltage, but proper

selection of the inductor and the output capacitor also

plays a big role. If a larger inductance value or a

smaller capacitance value is used, the output ripple

voltage will increase because the capacitor will be

slightly overcharged each burst cycle. To reduce the

output ripple, increase the output capacitance value,

or add a 10pF feed-forward capacitor in the feedback

network of the SS8028 (see the circuits in the

Typical Applications section). To add this small

inexpensive 10pF capacitor will greatly reduce the

output voltage ripple.

TYPICAL APPLICATION CIRCUITS

Boost Converter

SEPIC Converter

VCC

SW

SHDN

FB

GND

G5111

C2

22µF

C1

4.7µF

R2

120k

2.5V to 4.2V

R1

390k

5V

50mA

D1

VCC

SW

SHDN

FB

GND

C2

22µF

C1

4.7µF

R2

270k

V

2.5V to 4.2V

R1

470k

3.3V

60mA

1

L2

10µH

D1

VCC

SW

SHDN

FB

GND

C2

22µF

C1

4.7µF

V

IN

5V

50mA

D1

GND

C2

22µF

C1

4.7µF

IN

3.3V

60mA

L1:MURATA LQH3C4R7M24

D1:MOTOROLA MBR0520

L1,L2:MURATA LQH3C100K24

D1:MOTOROLA MBR0520

L2

10µH

D1

C3

1uF

L1

10uH

L1

4.7uH

R1

30_1%

R2

120k_1%

Dimming Ratio>50:1

Drive 2~4 White LEDs

R3

308k_1%

R4

660k_1%

VBIAS(+3.3V)

PWM Dim

PWM Dimming Control

VH=3.3V

VL=0V

Freq=160~240Hz

D2(Optional)

18V

C2

1µF

D1

MBR0520

L1

10µH/0.5A

SW

VCC

SHDN

FB

GND

VBAT

2.5V~5.5V

C1

4.7µF

ON/OFF Control

R1

30_1%

R2

120k_1%

Dimming Ratio>50:1

Drive 2~4 White LEDs

R3

308k_1%

R4

660k_1%

VBIAS(+3.3V)

PWM Dim

PWM Dimming Control

VH=3.3V

VL=0V

Freq=160~240Hz

D2(Optional)

18V

C2

1µF

D1

MBR0520

L1

10µH/0.5A

SW

VCC

SS8028

SHDN

FB

GND

VBAT

2.5V~5.5V

C1

4.7µF

ON/OFF Control

White LED Driver

Rev.2.02 12/06/2003