The LTC3870 is a PolyPhase® step-down slave controller specially designed for multiphase operation with the LTC3880 and LTC3883 digital power system management DC/DC controllers. It provides a small and cost effective solution for supplying very large currents by cascading it with a LTC3880 or LTC3883 controller. A peak current mode architecture provides the LTC3870 with excellent current sharing from phase to phase and from chip to chip. Coherently working with the LTC3880 or LTC3883, the LTC3870 does not require additional I2C addresses, and it supports all programmable features as well as fault protection. The constant switching frequency can be synchronized to an external clock from the LTC3880 or LTC3883 from 100 kHz to 1MHz.