FEATURES • High-Efficiency DC/DC WLED Bias Supply • Internal 40V, 0.55Ω Power MOSFET • Up to 10 WLEDs per String • Two Peak Current Options: − ACT6357: 0.5A − ACT6358: 1A • Supports Analog and PWM LED Dimming • Integrated Over-Voltage Protection (OVP) • Programmable Soft-Start Function • Thermal Shutdown • Cycle-by-Cycle Over Current Protection • Tiny TDFN33-8 Package APPLICATIONS • TFT LCD Displays • Smart Phones • Portable Media Players • GPS/Personal Navigation Devices GENERAL DESCRIPTION The ACT6357 and ACT6358 step-up DC/DC converters drive white LEDs with an externally programmable constant current. These devices feature integrated, 40V power MOSFETs that are capable of driving up to ten white LEDs in series, providing inherent current matching for uniform brightness. WLED brightness adjustment is easily achieved via a dual-function pin, which accepts either a PWM or an analog dimming control signal. The ACT6357 and ACT6358 feature a variety of protection circuits, including integrated over voltage protection (OVP), programmable soft-start, cycleby-cycle current limiting, and thermal shutdown protection circuitry. The ACT6357 has 500mA current limit, while the ACT6358 has 1A current limit. Both parts are available in a small 3mm x 3mm 8-pin TDFN33-8.
