The ISL6554 is the first controller in the Intersil Multi-Phase family without the programmable droop feature. The ISL6554 in combination with the HIP6601A, HIP6602A or HIP6603A companion gate drivers and Intersil MOSFETs form a complete solution for high-current, high slew-rate applications. The ISL6554 regulates output voltage, balances load currents and provides protective functions for two to four synchronous-rectified buck-converter channels. A novel approach to current sensing is used to reduce overall solution cost. The voltage developed across the lower MOSFET's parasitic on-resistance during conduction is sampled and fed back to the controller. This lossless current-sensing approach allows the controller to maintain phase-current balance between the power channels and overcurrent protection.