Multiphase step-down DC/DC controller delivers up to 260A

Up to eight phases with two ICs can be parallelled and can be clocked out-of-phase to minimise input and output filtering for very high current requirements up to 260A. Applications include power distribution and industrial systems, FPGA, DSP, processor and ASIC supplies.

The LTC7851/-1’s internal current share loop equalises current between phases when parallelled, enabling accurate current sharing between phases across multiple ICs, both in steady state and during a transient event. It operates with a V_CC supply voltage from 3 to 5.5V, is designed for step-down conversion from an input voltage from 3 to 27V and produces one to four independent output voltages ranging from 0.6 to 5V. The device’s voltage mode control architecture allows for a selectable fixed operating frequency from 250kHz to 2.25MHz or it can be synchronised to an external clock over the same range. The output current is sensed by monitoring the voltage drop across the output inductor (DCR) for maximum efficiency or by using a low value sense resistor. The onboard differential amplifiers provide true remote output voltage sensing for all outputs of both V_OUT and ground terminals for high accuracy regulation.

The LTC7851-1 is similar to the LTC7851, but with a lower current sense amplifier gain, suited for power train applications using DrMOS with internal current sense capability. Additional features for each phase include current monitoring, adjustable current limit, programmable soft- start or tracking and a power good signal. Furthermore, it maintains ±0.75% reference voltage accuracy over an operating temperature range of -20 to +85°C.

The LTC7851/-1 is housed in a 58-lead 5x9mm QFN package and is available from stock. 1000unit quantity pricing starts at $4.27 each.