The TPS5140 is a dc/dc controller that incorporates three synchronous-buck controllers and one nonsynchronous 12-V boost converter on one chip to power the voltage rails needed by notebook peripheral components. On-chip high-side and low-side synchronous rectifier drivers are integrated to drive less expensive N-channel power MOSFETs. The nonsynchronous boost converter includes the N channel power MOSFET and supports 120 mA for the PCMCIA power supply. The outputs are controlled independently and two of the synchronous-buck controllers operate 180 degrees out of phase, with the third lowering the input current ripple and allowing a smaller input capacitance to reduce power supply cost. For higher efficiency under all load conditions, the TPS5140 automatically adjusts each channel from the PWM mode to the skip mode independently.