SC446 Datasheet, PDF (1/1 Pages) Semtech Corporation – High Efficiency Integrated Driver for 3-Strings of 100mA LEDs

SC446
POWER MANAGEMENT
Features
High E ciency Integrated Driver for
3-Strings of 100mA LEDs
Description
„ Wide input voltage range from 4.5V to 27V
„ 36V maximum output voltage
„ Drives up to 30 WLEDs in 3 strings
„ Programmable LED current for up to 100mA 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-16 EDP package
„ Pb Free, Halogen Free, andWEEE/RoHS Compliant
The SC446 is a high-e ciency multiple string WLED driver
with an integrated boost converter. It operates over a
wide input range from 4.5V to 27V with a maximum out-
put voltage of 36V and a 2.5A internal power switch. It
can drive up to thirty WLEDs in 3 strings with current up
to 100mA 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 10 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.
Applications
„ Medium-sized LCD panel
„ Notebook Display
„ Automotive Car Navigation Display
„ Sub-Notebook and Tablet Computer Displays
„ Portable Media Players
The SC446 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 SC446 is available in a thermally-enhanced TSSOP-16
EDP package.
Typical Application Circuit
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January 28, 2010
www.semtech.com ₁