Quote:
Originally Posted by Ed Sparks
Hmmm.....
Says in the data sheet that these regulators have short circuit and thermal protection built in. In other words, given that the power source is within spec, you should not be able to destroy them (no matter what the load). Maybe some were accidently powered up with reverse polarity at some point. I'm leaning toward the explanations in Daniel's list.
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Thanks.
The short circuit protection in this chip is a current limiter circuit. That said, the chip wont survive prolonged usage at max current (>140mA).
The Thermal protection is also a short term stopgap measure. The output current is driven by a FET which as it heats up provides lower current. This will slow down the heating process but will still fail if the chip is allowed to continously run at high current.
I've never really had issues with a National Semiconductor chip. They tend to be much more robust that some of the other knock off chips. Makes me wonder if something else on the board is drawing too much current.