Low voltage problems with the 16LF819

[Eugeneo]

I've programed a 16LF819 at 5V VDD and it runs flawlessly at 5V. When I revert to 3.3V, it doesn't do anything. Here are the things I've done.

Confirmed the part number on the chip (LF series chip)
Inserted a 4mhz crystal in place of the internal osc
Set the internal osc speed at 8,4,2,1 mhz
Tied the MCLR pin to VDD
Checked the config bits for NO LVP and NO MCLR

Just a note. All of these tests work when VDD is at 5V but none of them work at 3.3V.

Please any suggestions at this point would help.

Thanks

[MikeValencia]

Did you try disabling BOR?

In many LF chips (not all), BOR needs to be disabled.

[Eugeneo]

That worked !!!!

Thanks a million, now I can finally get on with the coding