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. The skip mode enables a lower operating frequency and shortens the pulse width to the low side MOSFETs, thereby increasing the efficiency under light load conditions. To further extend battery life, the TPS5140 features dead-time control and very low quiescent current. Resistorless current protection and the fixed high-side driver voltage simplify the system design and reduce the external parts count.