Table of Contents
A reliable and high-performance power supply is an essential component of any electronic system. This is especially true for a portable application that demands high-efficiency because a significant electrical system weight is the battery.
|Targets||Input voltage (V)||Output voltage (V)||Output current minimum (A)|
Single Supply DesignThe final supply design, specified in the table below, has a very high overhead. This is designed to support the sponsor's demand for the ability to include more PC/104 interface boards (ADC, DAC, etc.) which demand much more current than more power-frugal digital-only circuits (such as the Lynx computer).
|Targets||Input voltage (V)||Output voltage (V)||Required current (A)||Maximum current (A)||Overhead (%)|
The schematic shown below is the final design for the triple-supply. It includes all necessary connectors to support a full, production-quality board. The three supplies are symmetric to allow minimum time-to-build for the board design. Each of the supplies used a Linear Technologies LTC1871 and a common set of power electronics and passive devices.
Layout and FabricationThe layout was performed in the Cadsoft Eagle editor and the design files are available to anyone with guest access to this project. An image of the layout is given below.
The first board was constructed in the RIT CEMA Lab with the assistance of Mr. Jeff Lonneville. The populated board is shown below.
ErrataThere are a few issues encountered with the first design, these are:
- R1 label misplaced and overlaps another component's pads
- C15, C16 pads have silkscreen overlapping one of their pads, this causes a 'downward' shift in the device but no ill effects
- Q1-3 have no fiducials (orientation markers)
- J3-7 part layout differs from ordered part in the hold-down post placement. The deisgn has a center plastic hold-down, while the ordered part has two-edge metal hold-downs. These metal hold-downs can be removed by hand and the ordered parts are used successfully.
- C2, C16, C22 parts missing from original order because of typo in BOM