USB Variable Power Supply (Version 2)

We pushed the requirements a little harder this time. We wanted a USB controllable device for setting and monitoring voltage. We wanted a smaller case. Also we needed a little broader voltage range.

This device goes from 1.5 volts to 5.1 volts.

Our projects never use 5V anymore. These days, we usually require 2.8V, 3.3V or LiIon simulation from 3.6V to 4.2V. This little variable power supply covers them all.

A PIC18F24K50 is used to monitor the voltage with 100mV accuracy. Press the monitor button to monitor current with 10mA accuracy.

The power supply is continuously adjustable from 1.7 to 5.2 volts using an encoder. The low and high voltages are shown on the display below along with some of our most used voltages:

Documents:

• Schematic page: USB_Power_v2_schematic.pdf
• Source code: USB_Power_v2_src.zip
• Source schematic: USB_Power_v2_eagle.zip*
• Microchip PIC18F24K50 datasheet

*The Source schematic file includes:

• USB_Power_v2_02.sch: Eagle schematics
• MPI-PCA02-01 rev 01.doc: Manufacturing Process Instructions
• PCA-PW002-01-BOM_02.xls: PCA parts list
• Pacificware.lbr: Eagle component library (schematic and layout symbols) of newly created components specific to this project