The AL3157 is a low noise, constant frequency charge pump DC/DC converter that uses a Dual mode load switch (1x), and doubling (2x) conversion for driving white LEDs. Low external part count (one 1µF flying capacitor and two 2.2µF capacitors at VIN and VOUT) make this part ideally suited for small, battery-powered applications The AL3157 drives 3 channels at up to 30mA for small screen backlighting and an additional channel up to 210mA for LED Flash or LED Flashlight – All from a 2.7V to 5.5V input. The AL3157 uses two control inputs (EN1/2) to enable/disable it and PWM dim the LED current. EN2 controls/PWM dims the backlight LEDs at 30mA per channel and EN1 controls/PWM dims the Flash/Flashlight LEDs at 210mA. Each output of the AL3157 is equipped with built-in protection for VOUT short circuit and auto-disable for LED failure conditions. Built-in soft-start circuitry prevents excessive in-rush current during start-up and mode switching. A low-current shutdown feature disconnects the load from VIN to reduce quiescent current less than 1µA. The AL3157 is available in a lead-free, space-saving, thermally enhanced 12-pin 3 x 3mm DFN package.
- Mobile phone Backlighting + flashlight
- Mobile phone Backlighting + camera flash
- Small screen backlighting + auxilliary lighting