What this controller is and where it fits
The Maxim Integrated MAX25603AUI/V+ is a 4-channel DC-DC LED driver controller designed for automotive exterior and interior lighting applications. It operates as a controller — no internal switching FETs — so you pair it with external N-channel MOSFETs sized to your LED string voltage and current. The part supports both step-down (buck) and step-up (boost) topologies, giving flexibility for a single 12V or 24V automotive bus driving series LED strings from 5V up to 60V supply. Four independent outputs let you control multiple LED channels (e.g., daytime running lamps, turn signals, matrix beams) from one IC, saving board space versus a multi-controller approach.
Automotive qualification and temperature range
AEC-Q100 qualified and rated for -40°C to +125°C junction temperature, this controller is built for under-hood and exterior lighting modules where thermal cycling and vibration are routine. The wide supply range — 5V minimum to 60V maximum — covers load-dump and cold-crank transients common on automotive power rails without requiring external clamp circuitry.
Dimming and switching flexibility
Both analog and PWM dimming are supported, allowing either continuous current adjustment or high-frequency PWM for color-temperature control in RGB systems. The switching frequency is programmable from 200 kHz to 440 kHz — lower frequencies reduce switching losses and ease EMI compliance; higher frequencies shrink the inductor and capacitor footprint. No internal switch means the external MOSFET choice determines the actual output current capability; the controller itself handles the gate drive and regulation loop.