Allegro's boost converter IC is optimized to drive white LEDs

Oct. 1, 2004
Allegro MicroSystems, Inc. has developed a high-frequency boost converter with constant current output, ideal for driving white LEDs or similar loads.
The A8430 is a non-inverting boost DC-DC converter, providing 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 thus leading to longer battery life.

The A8430 comes in an ultra-thin 3x3 mm 5-lead QFN package only 0.75 mm high, and utilizes an industry-standard pinout and equivalent SOT-23-5 footprint - an easy drop-in replacement for competitive products.

Other features of the A8430 include:

  • 2.5 V to 10 V input voltage
  • Drives up to 4 LEDs at 20 mA from a 2.5 V supply
  • Drives up to 5 LEDs at 20 mA from a 3.0 V supply
  • 1.2 MHz switching frequency allows use of small external components
  • 300 mA internal switch current limit
  • LED brightness control
  • Load current set by external feedback resistor
"Not only does our A8430 QFN-5 drop-in to the same footprint as SOT- and TSOT-23-5 packages, but it reduces the profile to just 0.75 mm nominal height," said Allegro's strategic marketing manager Mark Gaboriault.

Allegro MicroSystems, Inc. is a supplier of advanced mixed-signal power semiconductors and Hall-effect sensors targeted toward the automotive, communications, computer/office automation, consumer and industrial markets. It maintains a leadership position in the integrated magnetic sensor and integrated motor driver product segments. With over 2,000 employees, Allegro is headquartered in Worcester, MA.