Texas Instruments 3.5 a step-down switch regulator

The L4973 is a step-down monolithic power-switch regulator that delivers 3.5a at a fixed voltage of 3.3V or 5.1V, and uses a simple external divider to output adjustable voltages up to 50V. The device is implemented using a BCD hybrid technology, using an internal power D-MOS transistor (typical RDS(on) of 0.15Ω) for very high efficiency and very fast switching time.

Internal schematic diagram

Switching frequencies up to 300 kHz can be achieved (maximum power consumption of the package must be observed). A wide range of input voltages ranging from 8 V to 55 V and output voltages adjustable from 3.3V to 40 V covers most applications today.

Block diagram

Features of this new generation of DC-DC converters include pulse current limiting, a burp-card mode for output short-circuit protection, voltage feedforward regulation, soft starting, input/output synchronization, feedback loop disconnection prevention, zero current consumption suppression, and thermal shutdown. The packages available are plastic double row packs for standard assembly DIP18(12+3+3) and SO20(12+4+4) for SMD assembly.

Pin connection (top view)