POWER MANAGEMENT

1

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SC104

Micro Power Constant-Current

DC-DC Converter

March 22, 2005

The SC104 is a micro power dc-dc step-up converter

which converts an input voltage, in the range of 1.55V to

10V, to a constant current. The part features a range of

user programmable voltages and currents including

dynamic adjustment of the “constant” current. The

converter is capable of generating output voltages as

low as the input supply voltage and up to 38V. During

shutdown, the part draws a typical 500nA standby

current.

The output current is set by the external resistor R1.

Dynamic adjustment of the output current can be made

by the application of an analog voltage to the ADJ

input, or by PWMing this pin.

The peak switch current is programmable through the

external resistor R

inductors and battery technologies.

White LED supplies

Color LED supplies

Cellular phones

PDAs

Electronic books

Handheld computers

Wireless web appliances

Adjustable output current using pulse width

modulation or analog voltage input

38V output capability supports up to 10 white LEDs

Wide range of input voltages 1.55V to 10V

Low quiescent current

0.5µA standby current in shutdown

Programmable cycle by cycle current limit

Surface mount packaging (3x3mm 8pin MLP)

Output voltage and over-temperature protection

Description

Features

Applications

Typical Application Circuit - 6 LEDs

ENABLE

RSET

23.2R

LED2

D1

IOUT = 15mA

U1

SC104

1

2

3

4

5

6

7

8

ADJ

FB

GND

OUT

LX

IN

LIM

EN

LED1

LED3

VIN = 3V to 5V

LED5

RLIM

7.50k

LED4

CIN

4.7uF

IOUT ADJUST

L1

12uH

LED6

COUT

0.47uF