UCC3585

The UCC2585/UCC3585 synchronous Buck controller provides flexible high efficiency power conversion for output voltages as low as 1.25V with guaranteed ±1% DC accuracy. Output currents are only limited by the choice of external logic level MOSFETs. With an input voltage range of 2.5V to 6.0V it is the ideal choice for 3.3V only, battery input, or other low voltage systems. Applications include local icroprocessor core voltage power supplies for desktop and Notebook computers, and high speed GTL bus regulation. Its fixed frequency oscillator is apable of providing practical PWM operation to 700kHz.

With its low voltage capability and inherent "always on" operation, the UCC2585/UCC3585 causes VOUT to track VIN once VIN has exceeded the threshold voltage of the external P channel MOSFET. Tracking can be tailored for any application with a single resistor or disabled by connecting TRACK to VIN. For dual supply rail microprocessors this feature negates the need for external diodes to insure supply voltage tracking between the +3.3V and lower voltage microprocessor core supplies.

The UCC2585/UCC3585 drives a complementary pair of power MOSFET transistors, P-channel on the high side, and N-channel on the low side to step down the input voltage at up to 90% efficiency.

A programmable two-level current limiting function is provided by sensing the voltage drop across the high side P channel MOSFET. This circuit can be configured to provide pulse-by-pulse limiting, timed shutdown after 7 con-secutive faults, or latch-off after fault detection, allowing maximum application flexibility. The current limit threshold is programmed with a single resistor selected to match system MOSFET characteristics.

The UCC2585/UCC3585 also includes undervoltage lockout, a logic controlled enable, and softstart functions. The UCC2585/UCC3585 is offered in the 16 pin surface mount and through hole packages.