Analog Circuit Design Volume Three

Chapter 68

Dual output supply powers FPGAs from 3.3V and 5V inputs

Haresh Patel

Abstract

The dual output LTC1704, which can supply two voltages with its versatile high frequency switcher and its space-saving LDO controller, is described.

Keywords

Dual output supply

FPGA

LTC1704

Introduction

FPGAs often require multiple power supplies: one for the core voltage (usually 1.8V, but sometimes as low as 1.2V) and at least one more for the I/O circuitry (often 2.5V). The available input supply is either 3.3V or 5V. One way to provide the multiple step-down conversions is via multiple switcher-based power supplies; however, this may be more complicated and cumbersome than is warranted, especially if the I/O does not draw much current. In ...