The TPS40425 is a PMBus, synchronous buck, driverless controller. It operates in non-smart power mode in factory default setting, and it can operate in smart power mode after PMBus programming and power reboot. It can be configured as dual-output or 2-phase. It is also stackable up to 4 phases to support load current as high as 120 A. Interleaved phase shift for 2-, 3-, or 4-phases reduce the input and output ripples therefore reducing input and output capacitance. The wide input voltage range can support 5-V and 12-V intermediate supply buses. The 0.5% reference voltage satisfies the need of precision voltage to the modern ASICs. Using the PMBus standard, the TPS40425 device can program reference voltage, fault limit, UVLO threshold, soft-start time and turn-on and turn-off delay. In addition, the device implements an accurate measurement system to monitor the output voltages, currents and temperatures for individual channels.