The TPS65281/TPS65281-1 incorporates an N-channel back-to-back power MOSFET switch and a monolithic buck converter. The device is intended to provide a total power distribution solution for digital TV, set-top boxes, tablet PC and VOIP phones etc applications, where precision current limiting is required or heavy capacitive load or short circuit are encountered. A 100-mΩ independent power distribution switch limits the output current to a programmable current limit threshold between typical 75 mA and 2.7 A by using an external resistor. The current limit accauracy as tight as ±6% can be achieved at higher current limit setting. TPS65281 provides circuit breaker functionality by latching off the power switch during over-current or reverse-voltage situations. TPS65281-1 limits output current to a safe level by using a constant current mode when the output load exceeds the current limit threshold. An internal reverse-voltage comparator disables the power switch when the output voltage is driven higher than the input to protect the device on the input side of the switch in normal operation. The nFAULT output asserts low under over-current and reverse-voltage conditions. Back-to-back power MOSFETs structure prevents the reverse current injection from an active load at output port during shutdown of power switch. The buck DC/DC converter integrates power MOSFETs for optimized power efficiency and reduced external component count. A wide 4.5-V to 18-V input supply range to buck encompasses most intermediate bus voltages operating off 5-V, 9-V, 12-V or 15-V power bus. Constant frequency peak current mode control simplifies the compensation and provides fast transient response. The buck can be precisely sequenced and ramp up in order to align with other rails in the system with the soft-start pin. With SS pin floating, the built-in 1ms soft-start time prevents in-rush current. Cycle-by-cycle over current protection and hiccup operation limit MOSFET power dissipation in short circuit or over loading fault conditions. The switching frequency of the converter can be programmed from 300 kHz to 1.4 MHz with an external resistor at ROSC pin. With ROSC pin connecting to V7V pin, floating, or grounding, a default fixed switching frequency can be selected to reduce an external resistor. The TPS65281/TPS65281-1 is available in a 16-lead thermally enhanced QFN (RGV) 4-mm × 4-mm thin package.