Step-down slave controller generates up to 300A

16th January 2014

Nat Bowers

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Datasheet

Designed for applications including power distribution, redundant (n+1) supplies, industrial systems, DSP and ASIC power, the LTC3874 is a dual phase synchronous step-down slave controller from Linear Technology. When paired with a companion master controller, it is capable of generating currents up to 300A by extending the phase count in multiphase applications.

Compatible master controllers for the device include Linear's LTC3866, LTC3875 and LTC3774 which feature true current-mode control. These ICs enable the use of 0.2mΩ DC resistance power inductors without requiring a sense resistor to maximise converter efficiency and increase power density.

The LTC3874 provides all functions needed for multiphase slave designs: it employs a unique architecture that enhances the signal-to-noise ratio of the current sense signal to maximise efficiency while reducing switching jitter; and uses a peak current mode architecture which allows for accurate phase to phase current sharing, even for dynamic loads. Operating over an input range of 4.5-38V, the slave controller produces a fixed output voltage up to 5.5V and allows up to 12 phases to be paralleled and clocked out-of-phase (this minimises filtering).

The slave controller either has a fixed operating frequency of 250kHz-1MHz, or it can be synchronised to an external clock. The LTC3874 features powerful 1.1Ω onboard gate drivers to minimise MOSFET switching losses, as well as precise programmable current sense threshold limits of 16-72mV to minimise power loss and accurately set the over-current trip point.

Additionally, the controller provides selectable continuous or discontinuous light load operation, programmable phase shift control and overvoltage protection. Available now in a 28-lead 4x5mm QFN package, the LTC3874 is priced starting from $2.47 (USD) each in 1,000 unit quantities.