diode usage in linear regulators

[sweethomela8]

Hi, I've seen people connect the output of a linear regulator to a diode forward biased with the other end connected to the input of the regulator...whats the purpose of this diode?

voltage input---> REGULATOR------->output to load
| |
<---diode---------

thanks.

 

[IanP]

The diode that is connected between the output and input pins is for the protection of regulators in case the input is shorten and the output has a substantial electrolytic/tantalum capacitor connected to it ..
It is really individual issue for voltage regulators, and more details on requirement of a particular voltage regulator can be usually find in their data sheets ..
Eg. **broken link removed**
See section on protection diodes ..

IanP
:-D