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SS6639

1-Cell, 3-Pin, Step-Up DC/DC Controller

•

Guaranteed start-up from less than 0.9 V.

•

High efficiency.

•

Low quiescent current.

•

Fewer external components needed.

•

Low ripple and low noise.

•

Fixed output voltage: 2.7, 3.0V, 3.3V, and 5V.

•

Driver for external transistor.

•

Space-saving package: SOT-89 and TO-92.

•

Pagers.

•

Cameras.

•

Wireless Microphones.

•

Pocket Organizers.

•

Battery Backup Suppliers.

•

Portable Instruments.

The SS6639 is a high efficiency step-up DC/DC

controller for applications using 1 to 4 battery cells. Only

three external components are required to deliver a

fixed output voltage of 2.7, 3.0V, 3.3V, or 5V. The

SS6639 starts up from less than 0.9V input with a 1mA

load. The Pulse Frequency Modulation scheme offers

optimized performance for applications with light output

loading and low input voltages. The output ripple and

noise are lower than with circuits operating in PSM

mode.

The PFM control circuit operating up to 100 KHz

switching rate results in smaller passive components.

The space-saving SOT-89 and TO-92 packages make

the SS6639 an ideal choice of DC/DC controller for

space-conscious

applications,

such

as

pagers,

electronic cameras, and wireless microphones.

Using an external transistor driver pin (EXT), the

SS6639 is recommended for applications requiring

currents from several tens to several hundreds of

milliamperes.

SS6639-27

SS6639-30

SS6639-33

SS6639-50

GND

*Q1: Sanyo 25D1803S-TC 60V/5A/20W

+

EXT

D1

VOUT

*Q1

2SD1803

C2

10nF

R1

L1

33

µH

VIN

+

C1

47

µF

300

GS SS14

C3

100

µF

100mA Load Current Step-Up Converter

Rev.2.01 6/26/2003