SC440
High Efficiency Integrated Driver
for 6-Strings of 30mA LEDs
POWER MANAGEMENT
Features
Wide input range 4.5V to 21V
36V maximum output voltage with adjustable OVP for
smaller output capacitor
Drives up to 60 WLEDs in 6 strings
Programmable WLED current for up to 30mA per
string
1% string-to-string current matching
2.5A integrated power switch
Up to 91% efficiency
0.2% to 100% PWM dimming
Analog dimming
800KHz switching frequency for small external com-
ponent
Open/short LED protection
Short LED protection disable
<1uA shut-down current
Thermal protection
4mm x 4mm x1mm MLPQ-24 package (WEEE & RoHS
compliant)
Description
The SC440 is a high-efficiency multiple string WLED driver
with an integrated boost converter. It operates over a wide
input range from 4.5V to 21V with a maximum output
voltage of 36V and a 2.5A internal power switch.
It can drive up to 36V output voltage in 6 strings with
current up to 30mA per string. The string-to-string current
matching is 1% typical, 3% maximum and 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 800kHz switching frequency enables the user to
optimize the external component sizes for high efficiency.
When there are fewer LEDs in each string, users can use
a lower output voltage protection level which yields an
allowable reduction in associated costs, size and voltage
ratings of the output capacitor.
The SC440 also features a comprehensive open and
short circuit LED protection functions. It disables the
corresponding strings with LED open or LED short
conditions while keeping other strings under normal
operation. This feature allows LCD panels to remain
viewable even under LED failure, wire disconnect, or short-
circuit conditions. The short LED protection function can
be disabled. The internal thermal shutdown protects the
IC from overheating at abnormal conditions. The SC440
is available in a common 4mm x 4mm x1mm MLPQ-24
package.
Applications
Medium-sized LCD panel
Notebook Display
White LED Power Supplies
Sub-Notebook and Tablet Computer Displays
Portable Media Players
LCD Monitors
Digital Video Cameras
Typical Application Circuit
Vin (4.5V - 21V)
1
2
SW
VIN
SCP_EN
EN
FFLAG
PWM
OVPRTN
SW
VOUT
OVPIN
6 Strings
SC440
IO1-6
-6
IOSET
AGND
6
10
COMP
SS
EDP
PGND
IOGND
PGND
April 20 2007
1
SEMTECH
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