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Author Topic: How do voltage regulators fail?  (Read 1940 times)
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Hofstadter's Law: It always takes longer than you expect, even when you take into account Hofstadter's Law.
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Most voltage regulators ICs have built-in thermal protection. This means that if you don't have a big enough heatsink on them, they reduce the output voltage (and hence current draw) until the power dissipation is low enough to keep them within temperature limits. They recover if you turn the power off and let them cool down.

I had this happen to me when I was using a 7912 regulator bolted to a large piece of aluminium sheet as a heatsink. After a while, the output voltage would drop slightly and ripple started appearing on the output.Although the heatsink was quite large, the aluminium was too thin to carry the heat away fro the IC. Using a thicker gauge of aluminium cured the problem.

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