BL8548

BL8548 Max. 3MHz, Variable Frequency Step-up DC/DC Converter DESCRIPTION The BL8548 variable frequency step-up Converter drives white LEDs with a constant current to provide backlight in cell phones, PDAs, and other hand-held devices. It features allowing series connection of the white LEDs so that the LED currents are identical for uniform brightness. An enable input can be pulsed repeatedly to adjust LEDs brightness. The fast 3MHz operation frequency allows for smaller capacitor and inductor. Fault condition protection uses cycle-by cycle current limiting to sense maximum inductor current and over-voltage protection. The 0.2V low reference voltage minimized the power loss across the current sense resistor. The converter can operate from 2V to 6V, and capable of delivering maximum 250mA output current at 4-LEDs application with 3V input voltage. Quiescent current drawn from power source is as low as 120uA. All of these features make BL8548 be suitable for the portable devices, which are supplied by a single battery. FEATURES  Up to 19V Output Voltage  Wide Operation Range: 2V to 6V  Maximum 3MHz Operating Frequency  PWM Dimming Control  Shutdown Current <1uA  Current Limit Cycle-by-Cycle  Low Current Sense Threshold: 200mV  19V Over Output Voltage Protection  Compact SOT23-6 Package APPLICATIONS  Compact Back Light Module  Power Source for LED  Constant Current Source BL8548 is available in SOT23-6 package that is PB free. TYPICAL APPLICATION BL8548 www.bel...