SC445 High Efficiency Integrated Driver for 4-Strings of 150mA LEDs POWER MANAGEMENT Features Description The SC445 is a high-efficiency multiple string WLED driver with an integrated boost converter. It operates over a wide input range from 4.5V to 27V and can sustain fast Vin transient up to 5V/µs. It can drive up to forty WLEDs in 4 strings with current up to 150mA per string. The stringto-string current matching 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. Wide input voltage range from 4.5V to 27V Sustain fast Vin fluctuation up to 5v/µs 42V 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 Enable 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 Short LED protection enable/disable Thermal protection with auto-recovery Thermally enhanced TSSOP-20 EDP package Lead-free, Halogen-Free and WeEE/RoHS Compliant The 700KHz switching frequency enables the user to optimize the external component sizes for efficiency. 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 SC445 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, unaffected 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. Applications Medium-sized LCD panel Notebook Display Automotive Car Navigation Display Sub-Notebook and Tablet Computer Displays Portable Media Players The SC445 is available in a thermally-enhanced TSSOP-20 EDP package. Typical Application Circuit Vin (4.5V -27V) 1 2 VIN SW SW VOUT SCP_EN 4 Strings OVPIN OVPIN EN FFLAG PWM SC445 COMP IO1-4 IO14 4 12 IOSET IOSET AGND AGND IOGND SS EDP Revision 2.1 PGND PGND PGND