T6309B

tm TE CH T6309B Micropower Step-up DC/DC Converter FEATURES Matched LED Current with Overvoltage www.DataSheet4U.com Protection Drives LEDs in series Up to 85% Efficiency Low 400mV Feedback Reference, Optional 1.19V Feedback Reference Internal Current Limit 250mA Under Voltage Lock Out Circuits 0.1uA Low Shutdown Supply Current 6-pin SOT-23 Package ESD Human Body Mode Over 5KV GRNERAL DESCRIPTION The T6309B is a step-up DC/DC converter that drives LED with a constant current. The device can driver up to 3 series LEDs from a single-cell Li-Ion battery. Series connection of the LEDs provides constant LED current that results in uniform brightness. The T6309B features a minimum off-time current-limited PFM control scheme. The LED current is set with an external sense resistor (Rs) and is regulated by the feedback pin (FB) that regulates the voltage across the sense resistor to 400mV (typ). The low 400mV feedback reference voltage reduces power loss and improves efficiency for LED driver applications. Optional 1.19V feedback reference is available for normal output voltage applications like LCD bias. Output overvoltage protection (OVP) is integrated to prevent damage in case of output open circuit condition (e.g. faulty LED). The OVP pin can monitor the output voltage and turn off the converter in the event of overvoltage condition. The T6309B is available in SOT23-6 packages. APPLICATIONS Cellular Phones Portable Communication Devices Handheld Elect...