DC/DC Controller Integrates Margining And Tracking

In either a 5 mm x 5 mm QFN or 28-lead SSOP, the LTC3770 synchronous step-down dc/dc controller integrates tracking and sequencing functions, and output margining capabilities. Its constant on time, valley current mode architecture pairs with a minimum on time of 50 ns, allowing the control loop to respond instantly to load steps. The device employs current mode control and can operate without a sense resistor by sensing the voltage drop across a synchronous power MOSFET. Capable of operating at very low duty cycles, outputs as low as 0.6V are possible from input voltages as high as 32V. Operating frequency is set via an external resistor and, for applications requiring constant frequency, a phase-lock-loop function synchronizes the chip to an external clock. Other features include an output voltage accuracy of ±0.5% at room temperature and ±0.67% from 0°C to 85°C, an open-drain power-good output, and an operating temperature range from -40°C to +85°C. LINEAR TECHNOLOGY CORP., Milpitas, CA. (800) 454-6327.