The TPS65280 incorporates dual N-channel MOSFET power switches for USB power distribution systems that require dual power switches in a single package. It also integrates a buck converter which regulates an accurate 5-V output voltage from a 5.5-V to 18-V power bus to supply the power for power switches. The device is intended to provide a total USB power distribution solution for digital TV, set-top boxes, VOIP phones and tablet PC applications, where precision current limiting is required or heavy capacitive loads or short circuits are encountered.

A dual 85-mΩ independent power distribution switch limits the output current to a typical 1.2 A (manufacture trim 0.8 A, 1.6 A, and 2 A available options) when output current load exceeds the current limit threshold. TPS65280 device limits output current to a safe level by using a constant current mode when output load exceeds the current limit threshold. After delitching time, TPS65280 provides circuit breaker functionality by latching off the power switch during over-current or reverse-voltage situations. Two back-to-back power MOSFETs prevent the current injects from output to input in shutdown. An internal reverse-voltage comparator disables the power switch when the output voltage is driven higher than the input to protect the circuits on the input side of the switch in normal operation. The nFAULT1/2 output asserts low during over-current and reverse-voltage conditions.

The buck DC/DC converter integrates power MOSFETs for optimized power efficiency and reduced external component count for a fixed 5-V output voltage. A wide 5.5-V to 18-V input supply range to buck encompasses most intermediate bus voltages operating off a 9-V, 12-V or 15-V power bus. Constant frequency peak current mode control simplifies the compensation and fast transient response. Equipped with enable and soft-start pins, the DC/DC can be precisely sequenced and ramp up in order to align with other rails in the system. Cycle-by-cycle over-current protection and operating in hiccup mode limit MOSFET power dissipation during buck output 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 the ROSC pin. With the ROSC pin connecting to the V7V pin, floating, or grounding, a default fixed switching frequency can be selected to reduce the external component. The internal oscillator can be synchronized with a free-run external clock in frequency.Read more