6-channel boost LED driver with integrated switch
The LP8557AYFQT is a 6-output DC-DC boost regulator from Texas Instruments, designed to drive LED backlight strings. It integrates the switching FET internally, delivering up to 28V output and 25mA per channel — enough series headroom for a string of six to eight white LEDs in a typical 3.0V to 3.3V Vf stack. Dimming is handled via PWM, which is the standard approach for backlight brightness control — the PWM signal modulates the LED current on/off at a frequency above visible flicker, preserving color accuracy across the brightness range.
Switching frequency and supply range
The oscillator is pin-selectable between 500 kHz and 1 MHz. The choice trades board area against a percent or two of battery life. The undervoltage lockout sits below 2.7 V, so the driver starts cleanly from a battery that has not yet reached full charge.
Rated for -30°C to +85°C ambient — this is the industrial temperature band. A handheld device or indoor display that sees 60°C on a hot day still has 25°C of margin before the junction hits the 125°C abs-max. The 16-DSBGA package is a 0.5 mm pitch wafer-level chip-scale package — the board must have a soldermask-defined pad and a stencil aperture that matches the datasheet footprint exactly. No underfill is required for most portable applications, but a drop-test qualification is recommended for wearable or handheld designs.