Machine Design

Converters For Portable Electronics

The A8430 and A89431 high-frequency boost converters feature constant current output for driving white LEDs or similar loads.

The A8430 is a noninverting boost dc-dc converter with programmable current output to 36 V for driving white LEDs in series. An external resistor sets output current, which varies with a PWM signal or a control voltage at the top of the sense resistor when applications require dimming control. The A8430 comes in an ultrathin 3 3-mm five-lead QFN package that is 0.75-mm high and uses industry-standard pinout and SOT-23-5 footprint.

The A8431 has the same features packaged in a 2 x 3-mm six-lead QFN and adds 2-V overvoltage protection. It features 2.5 to 10-V input voltage, drives up to four LEDs at 20 mA from a 2.5-V supply or five LEDs at 20 mA from a 3.0-V supply. The device has 1.2-MHz switching frequency, 300-mA internal switch current limit, LED brightness control, and load current set by external feedback resistor.

Allegro MicroSystems Inc.,
115 Northeast Cutoff, Worcester, MA 01606,
(508) 853-5000,

TAGS: Technologies
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