AVR-Chat

At 01:23 PM 5/16/2005, Jim Wagner wrote:
>On the reverse diode between the input and output of the
>regulator: this is normally used to prevent reverse current
>flow through the regulator. This could occur if the input
>is suddenly forced to a low voltage while the output cap is
>still charged. The LM78xx family is not as sensitive to
>this as some and I rarely see this diode in 7805 circuits.

It's rare even to see it in the data sheets anymore, but if you look 
at the circuits, they all suffer from the same vulnerability.
The larger the cap on the output side (total of all caps) the greater 
the hazard.

The old motorola data sheets show it.