Running Regulator Under Voltage

Is there any disadvantage to running a Linear Regulator under the minimum voltage stated in the datasheet? For instance, In the datasheet of the LM7812C2T, it says the minimuim voltage in order to to get 12v out, is 14.5v in. However, if i run it at 12V, the actual output is around 11V.

Is there any reason this is a bad idea?

Thank you, Chris.


A certain amount of headroom is required by all linear regulators. With insufficient headroom, the devices main output transistor is not fully saturated and will therefore have a higher output resistance. The device might dissipate more power and dependent on the current drawn, get hotter than intended, possibly leading to a thermal shutdown when you least expect it.

My advice, just select a low drop out alternative or go switched mode. (see my question)

If you don't provide enough voltage to the regulator this may not behave as expected. As you can see, it deliver 11v instead of 12v. Even if 11v is ok for you, the regulator may not be able to provide as much cuurent as it is suppose to do. And there is some chances that your chip will heat very fast.

Category: voltage regulator Time: 2016-07-30 Views: 0

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