TPS65281-1RGVR

The TPS65281/TPS65281-1 integrates an N-channel back-to-back power MOSFET switch and a monolithic buck converter. This device provides an overall power distribution solution for applications such as digital TVs, set-top boxes, tablets, and VoIP phones, where precision current limiting is required or where high capacitive loads or short circuits may occur.

A 100mΩ discrete power distribution switch limits output current to a programmable current limit threshold between a typical value of 75mA to 2.7A using an external resistor. At higher current limit settings, a tight current limit accuracy of ±6% is achievable. Under overcurrent or reverse voltage conditions, the TPS65281 provides circuit breaker functionality by latching the power switch. When the output load exceeds the current limit threshold, the TPS65281-1 limits the output current to a safe level using a constant current mode. When the output voltage is driven above the input, an internal reverse voltage comparator disables the power switch to protect devices on the switch input during normal operation. During overcurrent and reverse voltage events, the nFAULT output is asserted low. The back-to-back power MOSFET structure prevents reverse current injection from active loads on the output port while the power switch is off.

To optimize power efficiency and reduce external component count, the buck DC/DC converter integrates power MOSFETs. The wide 4.5V to 18V input supply range to the buck converter covers most intermediate bus voltages operating from 5V, 9V, 12V, or 15V power buses. Constant-frequency peak current mode simplifies compensation and provides fast transient response. The buck output can be precisely sequenced and slew-rate controlled to align with other power rails in the system using the soft-start pin. When the SS pin is left floating, the built-in 1ms soft-start time prevents inrush current. Cycle-by-cycle overcurrent protection and discontinuous mode operation limit MOSFET power dissipation under short-circuit or load fault conditions. The switching frequency of the converter can be set between 300kHz and 1.4MHz using an external resistor on the ROSC pin. A default fixed switching frequency can be selected to eliminate the external resistor when the ROSC pin is connected to the V7V pin, left floating, or tied to ground.