SC446

SC446 High E ciency Integrated Driver for 3-Strings of 100mA LEDs POWER MANAGEMENT Features „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ Description 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 output 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 matching 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 optimize the external component sizes for e ciency. When there are fewer than 10 LEDs in each string, users can adjust the output voltage protection yielding an allowable reduction in associated costs, size and voltage ratings of the output capacitor. The SC446 also features comprehensive open and shortcircuit LED protection functions. It disables the corresponding 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. 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 Applications Medium-sized LCD panel Notebook Display „ Automotive Car Navigation Display „ Sub-Notebook and Tablet Computer Displays „ Portable Media Players „ „ Typical Application Circuit 9LQ 9 9   6: 9,1 9,1 (1 9287 293,1 293,1  6WULQJV 293571 3:0 6& ,2 ,2  &203 ,26(7 ,26(7 $*1' 66 ('3 3*1' 3*1' $*1'   January 28, 2010 www.semtech.com 1