Minimum supply Voltage for a 16F818?

[JohnKennedy]

Hi all

I'm using a 16F818 for my latest project and all works fine on a 5V supply.
I have now been asked if this could work on a lower supply rail 3.3v
I looked at the data sheet fig 15.2 and at the frequency I'm using it at (4MHz) I thought yep should work down to 2V according to datasheet, so i swapped my 78L05 for a 78L33 (3.3V equivalent) but to my suprise it doesn't work at all not a thing

So I looked back at the Datasheet and saw Fig 15.1 that shows 4V as the minimum voltage for a extended/industrial. I bought these as the Industrial version and are marked 16F818 - I/P are these the Industrial part or the Extended / Industrial as this is the only explanation I can see or is there something else i'm missing?

thanks

JFK

[Chas]

Check the part number closely. It is the PIC16LF818 that runs down to 2.0 V. The PIC16F818 is limited to 4.0V min. The PIC16LF818 is a dropin replacement that is just guaranteed to a lower voltage with some limitations, mostly in operating frequency.

[PCM programmer]

In addition to the F vs. LF issue, one other common reason for
failure to operate at a lower voltage is that Brownout reset is enabled.
Many PICs don't have a selectable Brownout voltage. It's permanently
set at about 4v. These PICs can only use Brownout if they are running at 5v.

[JohnKennedy]

thanks guys I'll check that

JFK

[vizitibi]

with my students we use this chip with internal osc at 8MHz, and this chip works correctly from 2.2V
the brown out detect must be off
config number is 3f10

sorry my wrong english....
tibor