Single-phase synchronous buck controller
The LTC3851EUD#TRPBF: Its 4V to 38V input supply range covers common 5V, 12V, and 24V rails, and the switching frequency is programmable from 250kHz to 750kHz via a resistor on the FREQ pin. With synchronous rectification integrated into the control loop, the controller delivers up to 99% duty cycle, making it suitable for high step-down ratios where the output voltage is close to the input rail. The single output phase targets moderate current applications where a multi-phase interleaved controller would add unnecessary complexity.
Control features and thermal envelope
Built-in control features include current limit, enable, frequency control, soft start, and output tracking — the tracking pin allows the output to follow an external reference during start-up, useful for sequencing multiple rails. The 16-lead WFQFN package (3x3mm) with exposed pad (supplier device package 16-QFN) requires a thermal land pattern on the PCB to conduct heat from the die to the board.
The reel quantity is not listed here, but the TR suffix indicates standard 7-inch or 13-inch reel packaging typical for QFN devices.