The ISL6558 is a multi-phase PWM controller, which in combination with the HIP6601B, HIP6602B, HIP6603B, or ISL6605 companion gate drivers form a complete solution for high-current, high slew-rate applications. The ISL6558 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 and improve efficiency. The voltage developed across the lower MOSFET during conduction is sampled and fed back to the controller. This lossless current-sensing approach enables the controller to maintain phase-current balance between the power channels, provide overcurrent protection, and permit droop compensation. Optional output voltage "droop" or active voltage positioning is supported via the DROOP pin. Taking advantage of this feature reduces the size and cost of the output capacitors required to support a load transient. In the event of an overvoltage, the controller monitors and responds to reduce the risk of damage to load devices. Undervoltage conditions are indicated through a PGOOD transition. Overcurrent conditions cause the converter to shutdown limiting the exposure of load devices. These integrated monitoring and protection features provide a safe environment for microprocessors and other advanced low voltage circuits.