Triple Output, 3-Phase Current Mode Step-Down Controller

The LTC3773 is composed of three independent synchronous buck regulator controllers. On-chip high-side and low-side synchronous rectifier drivers are integrated to drive N-channel MOSFETs from input voltages of 4V to 36V. The input ripple current is minimized by operating each controller 120 degrees out of phase, allowing a smaller input capacitor and inductor resulting in reduced power supply cost. The LTC3773 automatically adjusts from PWM mode to Burst Mode® operation to maintain high efficiency under light load conditions. In addition, two or all of the three outputs can be paralleled for higher current requirements.

This controller meets all the FPGA & DSP start-up profile requirements, including monotonic voltage ramp and minimum voltage rail rise time. Furthermore, the LTC3773 allows for coincident or ratiometric tracking. Independent Enables for each output allow sequencing to minimize demand on the power supply at start-up. Soft-start on each supply limits inrush current during start-up. All three supply voltages are offered in user-programmable options for maximum flexibility.

The LTC3773 is offered in a 36-Lead SSOP or a 38-Lead 5mm x 7mm QFN package and has an operating temperature range from -40°C to 85°C. The 1,000-piece price starts at $3.95.