Controller handles currents up to 300A by adding regulation phases

January 17, 2014 // By Graham Prophet
LTC3874 is a dual phase synchronous step-down slave controller that generates currents up to 300A, when paired with a companion master controller, by extending the phase count in multiphase applications.

Compatible master controllers include the LTC3866, LTC3875 and LTC3774, which 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 LTC3874 woks with Linear Technology’s low-DCR peak current mode controllers and provides all functions needed for multiphase slave designs, including accurate phase-to-phase current sharing, even for dynamic loads. It operates over an input voltage range of 4.5V to 38V and produces 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.

The LTC3874 has a fixed operating frequency from 250 kHz to 1 MHz or it can be synchronised to an external clock. The powerful 1.1-Ohm onboard gate drivers minimise MOSFET switching losses. Precise programmable current sense threshold limits from 16 mV to 72 mV minimise power loss and accurately set the over-current trip point. Additional features include selectable continuous or discontinuous light load operation, programmable phase shift control and overvoltage protection.

The LTC3874, in a 28-lead 4 x 5mm QFN packag, costs $2.47 (1,000).

Linear Technology; www.linear.com/product/LTC3874