A dual phase synchronous step-down slave controller has been released by Linear Technology Corporation that is claimed to generate currents up to 300A when 
paired with a companion master controller by extending the phase count in multiphase applications. The company highlights that compatible master controllers include its LTC3866, LTC3875 and LTC3774, which are said to all have true current-mode control and enable the use of low (0.2 milliohms) DC resistance (DCR) power inductors without any sense resistor to maximise converter efficiency and increase power density.
The new device is the LTC3874, joining the company’s existing low DCR peak current mode controllers and is able to provide all functions needed for multiphase slave designs, including accurate phase-to-phase current sharing even for dynamic loads. It is said to operate over an input voltage range of 4.5V to 38V and can produce a fixed output voltage up to 5.5V. Up to 12 phases can be paralleled and clocked out-of-phase to minimise filtering. Applications include power distribution, redundant (n+1) supplies, industrial systems, DSP and ASIC power.
This device is claimed to have a fixed operating frequency from 250kHz to 1MHz or it is possible to synchronised it to an external clock. The company adds that powerful 1.1 Ohm onboard gate drivers minimise MOSFET switching losses. Alomg with precise programmable current sense threshold limits from 16mV to 72mV that minimise power loss and can accurately set the over-current trip point. Additional features include selectable continuous or discontinuous light load operation, programmable phase shift control and overvoltage protection.
This device is available in a 28-lead 4mm by 5mm QFN package.
Linear Technology Corporation
