Computer Controlled Power Supply Test System

By: Steve Hageman

Here is an excellent example of the PIC-DAS being put to use. This small power supply test system was used to run qualification tests on a custom switching power supply, seen in the foreground. The PIC-DAS (Box with yellow top) controlled a triple output, constant current load bank (below PIC-DAS) which acts as a continuously variable load on the power supply. A relay multiplexer was built (box on top of DVM) to allow the Agilent 34401 DVM to read all the input and output voltages of the supply under test. The PIC-DAS DAC's control the active loads, while the digital I/O is wired to the relay multiplexer. The Input voltage to the supply is provided by an Agilent HPIB programmable DC supply, the 34401 DVM is also controlled via HPIB. The PIC-DAS is conveniently connected to the PC's serial port. A suite of tests was written quickly with Agilent VEE, a graphical test language.

The entire test setup was built in a day. The test suite was built in another day and from then on it was smooth sailing. A power supply can be tested over any input or output conditions in seconds versus the hour a manual test would have taken and you get graphs in seconds not hours!

This is why I built the PIC-DAS system to be flexible and completely self contained. It allows for the quick building of "one off" test system like this. let's face it, no one likes spending lot's of time building a one off test system for just a few weeks use, but when the test system can be put together in a day, the payoff is immediate and the task tends to get done and get done better than by hand.


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Updated - 7Jan01