SC104 Datasheet, PDF (1/12 Pages) Semtech Corporation – Micro Power Constant-Current DC-DC Converter

SC104
Micro Power Constant-Current
DC-DC Converter
POWER MANAGEMENT
Description
Features
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 enabling the use of a wide range of
LIM
inductors and battery technologies.
‹ 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
Applications
‹ White LED supplies
‹ Color LED supplies
‹ Cellular phones
‹ PDAs
‹ Electronic books
‹ Handheld computers
‹ Wireless web appliances
Typical Application Circuit - 6 LEDs
IOUT ADJUST
IOUT = 15mA
LED4
LED5
LED6
LED3
LED2
LED1
RSET
23.2R
VIN = 3V to 5V
COUT
0.47uF
U1
1
ADJ
2
FB
3
GND
4
OUT
SC104
8
EN
7
LIM
6
IN
5
LX
D1
CIN
4.7uF
ENABLE
L1
12uH
RLIM
7.50k
March 22, 2005
1
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