Four-channel linear LED driver for portable backlight and flash
The Microchip MIC2842AYMT-TR is a linear LED driver with four regulated outputs, each rated for 20 mA per channel. It uses a single-wire dimming interface, which keeps the MCU connection to one GPIO pin while controlling brightness across all four channels. Target applications include LCD backlight and camera flash in handheld devices, where the linear topology avoids the switching noise and inductor footprint of a boost converter.
20 mA per channel — sizing the LED string
Each of the four outputs sources 20 mA continuously. For a typical backlight with four white LEDs in parallel, that is 80 mA total from the supply rail. The linear regulator drops the difference between the LED forward voltage and the supply; with a 3V minimum input and a 3.2V typical white LED, the headroom is tight — the supply must stay above the LED stack voltage plus the dropout of the internal current sink. The internal switches are integrated, so no external current-setting resistor or transistor is needed for each channel.
Single-wire dimming — firmware overhead
The dimming interface uses a single-wire protocol, meaning one digital output from the host MCU controls brightness for all four channels simultaneously. No PWM timer channel per LED is required, which saves timer resources on small-pin-count controllers. The protocol timing is defined in the datasheet; expect a few hundred microseconds of firmware overhead per brightness update.
10-TMLF 2x2 mm — board area and thermal relief
The 10-TMLF package measures 2x2 mm with an exposed pad.
It is ROHS3 compliant.