Power Supply Test Jig Design

A good way I've found to test any power supply, switching or linear, is to invest in an electronic load, such as those made by Transistor Devices and others. They often turn up on the used test gear market, Greed-bay, or at ham radio swap meets.

The big advantage an electronic load has over just plugging stuff into a power supply is that you can apply precise load conditions in terms of voltage, current, etc. Most have metering which will tell you at least the output voltage and current being drawn, and they usually have test points to allow for connection of an O-scope for noise and transient analysis.

Personally, I like the ones from Transistor Devices the best. They're very well made, service docs are readily available from the manufacturer, and they Just Plain Work.

Happy hunting.

chris snipped-for-privacy@hotmail.com

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These are good for applying precise loads, or step loads. But the OP stated that he needs to measure ripple and transient response. Seeing as how the DUT is a DC-DC supply, I'm guessing that the ripple will be at typical SMPS switching frequencies and transients will require time resolutions of microseconds or less.

This is probably going to require voltage and current measurements beyond the capabilities of the electronic load. There may also be a requirement to monitor input parameters. Its possible to build data acquisition systems from scratch, but I'd question the OP's aversion to using a scope. A software controlled scope with data capture capable of measuring PS transients isn't cutting edge (i.e expensive) technology. The controller just sets up the scope and test conditions and then grabs a snapshot of the trace. Some simple s/w can compare the waveform to an envelope limit and produce a go-no go indication.

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A test jig will be needed to connect the dut to your test system. This will have suitable connectorization, specialized switchgear and wire routing to allow accurate measurements at a reasonable production speed. The design of a new jig will be required for each iteration or model of DUT hardware.

Test systems, however, have measurement and loading hardware, switching matrices and some kind of software with operator interface, reporting and statistical processing features. Building your own, even using out-of-the-box subsystems, standard interfaces and out-of-the-box software can be quite a project. Think in terms of man-years.

Suggest you research costs of dedicated commercial power supply test systems, gpib and other interface hardware and software.

There are some undedicated automated test systems out there that can be applied effectively in this kind of job. In the 80s and 90s, I saw the 'Pilot' automated test system used effectively, in conjunction with a suitable load - this contained its own measurement system and a PC serial inteface, running test programs in quickbasic.

RL