This document introduces the LTC3890 and LTC3891 step-down DC/DC controllers. These controllers can accept inputs from 4V to 60V and support single and dual battery automotive environments. They can also output 12V 25A. If no galvanic isolation is required between the input and output voltages, the LTC3890 and LTC3891 can replace expensive and bulky transformer-based converters. Compared to transformer-based solutions, the LTC3890 and LTC3891 step-down converters increase efficiency, reduce power loss in the supply lines, simplify layout and significantly reduce the bill of materials.
Design Note 1024 details how to use the LTC3890 (dual output) and LTC3891 (single output) step-down DC/DC controllers. These devices accept input voltages from 4V to 60V, making them suitable for single or double battery automotive environments and 48V telecom applications without needing snubbers or voltage suppression circuitry.
The document provides a configuration for a high-efficiency 2-phase converter that delivers 25A at 12V from inputs up to 60V. It includes information on component selection, specifically regarding inductor RMS and saturation current calculations, and notes the requirement for logic-level MOSFETs due to an internal VCC voltage of 5.1V.
The converter delivers a maximum of 25A at an output voltage of 12V.
The device directly accepts inputs from 4V to 60V.