Controller has phase-lock loop synchronisation

Up to 12 phases can be paralleled and clocked out of phase to minimise input and output filtering requirements for high-current applications (up to 200A).

The differential amplifier provides true remote output-voltage sensing of the positive and negative terminals, enabling high-accuracy regulation where IR losses occur through vias, trace runs and interconnects.

Applications include high-current ASIC and FPGA supplies, power-distribution buses, high-power audio amplifiers and network servers.

The LTC3855 operates with all N-channel MOSFETs from input voltages ranging from 4.5 to 38V and it can produce +/-0.75 per cent accurate output voltages from 0.6 to 12.5V.

The output current is sensed by monitoring the voltage drop across the output inductor (DCR) or by using a sense resistor.

Programmable DCR temperature compensation maintains an accurate and constant over-current limit over a broad temperature range.

The onboard 1.1Ohm gate driver minimises MOSFET switching losses and allows the use of multiple MOSFETs connected in parallel.

A fixed operating frequency can be programmed from 250 to 770kHz or can be synchronised to an external clock with its internal PLL.

The device's minimum on time of 90ns makes the LTC3855 suitable for high-step-down-ratio applications.

Tracking and sequencing functions allow the optimisation of power up and power down of multiple power supplies.

Additional features include current-mode control, an onboard LDO for IC power, programmable soft start, two power good signals and external VCC control.