High Eciency Integrated Driver for
4-Strings of 150mA LEDs
SC441C
POWER MANAGEMENT
March 04, 2010 1
www.semtech.com
Features
Applications
Description
Wide input voltage range from 4.5V to 27V
42V maximum output voltage
Drives up to 48 WLEDs in 4 strings
Programmable LED current for up to 150mA per
string
+/- 2% string-to-string current matching
Up to 90% eciency
Wide 0.2% to 100% PWM dimming range
Possible analog dimming
Integrated 2.5A power switch
700KHz switching frequency for small size
Adjustable OVP for cost-eective output cap selection
Open/short LED protection
Thermal protection with auto-recovery
Thermally enhanced TSSOP-20 EDP package
Pb Free, Halogen Free, andWEEE/RoHS Compliant
Medium-sized LCD panel
Notebook Display
Automotive Car Navigation Display
Sub-Notebook and Tablet Computer Displays
Portable Media Players
The SC441C is a high-eciency multiple string WLED driv-
er with an integrated boost converter. It operates over
a wide input range from 4.5V to 27V with a maximum
output voltage of 42V and a 2.5A internal power switch.
It can drive up to 48 WLEDs in 4 strings with current up
to 150mA per string. The string-to-string current match-
ing is 2% typical, 3% maximum. The overall eciency is
greater than 90% due to the low current sense voltage
and a low-impedance internal power switch. The wide
PWM dimming range boasts a ratio of 500: 1.
The 700KHz switching frequency enables the user to op-
timize the external component sizes for eciency. When
there are fewer than 12 LEDs in each string, users can ad-
just the output voltage protection yielding an allowable
reduction in associated costs, size and voltage ratings of
the output capacitor.
The SC441C also features comprehensive open and short-
circuit LED protection functions. It disables the corre-
sponding strings with LED open or LED short conditions
while maintaining normal operation of other, unaected
LED strings. This feature allows LCD panels to remain
viewable even under LED failure, wire disconnect, or
short-circuit conditions. The internal thermal shutdown
protects the IC from overheating at abnormal conditions.
The SC441C is available in a thermally-enhanced TSSOP-20
EDP package.
Typical Application Circuit
1
4
VOUT
SS
PGND
IOSET
IO1-4
COMP
OVPIN
AGND
VIN
SW
PWM
EN
OVPRTN
SW
FFLAG
PGND
IOGND
SC441C
4 Strings
1
12
Vin (4.5V -27V)
2
EDP PGND
IOSET
IO1- 4
COMP
SS
AGND
VOUT
OVPIN
Vout (42V)