A high-frequency boost converter with constantcurrent output targets the driving of white LEDs or similar loads.
The A8430 is a noninverting boost dc-dc converter that provides a programmable constant current output at up to 36 V for driving white LEDs in series. The output current is set with an external resistor, and can be varied with either a PWM signal or a control voltage at the top of the sense resistor when dimming control is required. Driving the LEDs in series ensures identical currents and uniform brightness, and is more efficient than charge pump solutions. The A8430 comes in a 3
3 3-mm five-lead QFN package that is 0.75-mm high and uses an industry-standard pinout and equivalent SOT-23-5 footprint. Other features include 2.5 to 10-V input voltage, use of a 1.2-MHz switching frequency that allows use of small external components, and 300-mA internal switch current limit.
Allegro MicroSystems Inc.,
115 Northeast Cutoff, Worcester, MA 01615,
(508) 853-5000, allegromicro.com