App note: Troubleshooting switching power supplies


Having problem with your switching power supply design? Or just curious on common switching power supply failures. Here’s a good resource from Micrel on troubleshooting power supplies.

This application note provides insight on troubleshooting and
taking measurements in switching power supplies. Specific
measurements include output ripple, line and load regulation,
efficiency, and transient response. Troubleshooting and
measurement of flyback and forward converter transformers
are also covered.
Common measurement mistakes are also demonstrated,
including using uncompensated scope probes. The final topic
is an in-depth example of troubleshooting an off-line flyback
power supply. Off-line flyback topologies involve all dc-dc
converter circuit blocks, plus the ac front end, thus cover most
troubleshooting problems.

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  1. A very timely link. I had a computer power supply on an old computer go out a few weeks ago. It wasn’t worth it to buy a replacement given the age of the computer- a P4 that I use as a CNC interpreter (linuxcnc). It is getting harder and harder to find computers with a parallel port however. I tried looking online for resources to help diagnose switching power supplies with limited success. This looks like a very good resource. I am going to open up the power supply and give it a shot.

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