SC441A_10 Datasheet, PDF (1/1 Pages) Semtech Corporation – High Efficiency Integrated Driver for 4-Strings of 150mA LEDs

SC441A
POWER MANAGEMENT
Features
High Efficiency Integrated Driver for
4-Strings of 150mA LEDs
Description
„„ Wide input voltage range from 4.5V to 21V
„„ 36V maximum output voltage
„„ Drives up to 40 WLEDs in 4 strings
„„ Programmable LED current for up to 150mA per
string
„„ +/- 2% string-to-string current matching
„„ Up to 90% efficiency
„„ Wide 0.2% to 100% PWM dimming range
„„ Possible analog dimming
„„ Integrated 3.0A power switch
„„ 700KHz switching frequency for small size
„„ Adjustable OVP for cost-effective output cap selection
„„ Open/short LED protection
„„ Thermal protection with auto-recovery
„„ Thermally enhanced TSSOP-20 EDP package
„„ Fully WEEE and RoHS compliant
„„ AEC-Q100 Grade 3 qualified
Applications
„„ Medium-sized LCD panel
„„ Notebook Display
„„ Automotive Car Navigation Display
„„ Sub-Notebook and Tablet Computer Displays
„„ Portable Media Players
The SC441A is a high-efficiency multiple string WLED driv-
er with an integrated boost converter. It operates over a
wide input range from 4.5V to 21V with a maximum out-
put voltage of 36V and a 3.0A internal power switch. It
can drive up to forty 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 efficiency 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 efficiency. 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.
The SC441A 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, unaffected
LED strings. This feature allows LCD panels to remain view-
able even under LED failure, wire disconnect, or short-cir-
cuit conditions. The internal thermal shutdown protects
the IC from overheating at abnormal conditions.
The SC441A is available in a thermally-enhanced TSSOP-
20 EDP package.
Typical Application Circuit
Vin (4.5V -21V)
SW
VIN
EN
SW
VOUT
OOVVPPIINN
FFLAG
OVPRTN
PWM
SC441A
4
IOIO11- -44
COMP
IIOOSSEETT
AAGGNNDD
SS
EDP
PPGGNNDD
IOGND
PGND
1
2
4 Strings
10
January 18, 2010
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