This document introduces a dual output DC/DC converter solution for powering Xilinx FPGAs. The solution uses Linear Technology's LTC3860 and LTC3861 dual channel voltage regulators to provide 1.2V to 5V core voltage and 1.2V to 3.3V I/O voltage to the FPGA.
The document addresses the power requirements of Xilinx FPGAs, which need multiple voltage rails including Vecint, Veco, and sometimes Vecaux. It highlights the importance of supply sequencing, tracking, and ramp time in these applications.
Three specific dual output DC/DC regulators are detailed: the LTC3407 for currents up to 600mA, the LTC3736 for 5A loads using 2-phase operation, and the LTC3708 for high-current applications exceeding 10A. The text provides application schematics, efficiency curves, and feature descriptions such as output tracking and programmable current limits.
| Max Supply Current (LTC3407) | 600mA |
|---|---|
| Input Voltage Range (LTC3407) | 2.5V to 5.5V |
| Output Voltage Range (LTC3407) | 0.6V to 5V |
| Max Supply Current (LTC3736) | 5A |
| Input Voltage Range (LTC3736) | 2.7V to 9.8V |
| Max Supply Current (LTC3708) | 15A |
| Input Voltage Range (LTC3708) | 3.3V up to 36V |
| Output Voltage Range (LTC3708) | down to 0.6V |
Core voltages range from 1.2V to 2.5V, with some mature products having 3V, 3.3V, or 5V.
The recommended ramp time (teepo) for the core voltage Vecint is less than 50ms during power-on.
The LTC3736 is available in a tiny (4mm x 4mm) thermally enhanced QFN package or a 24-lead SSOP package.