hi, i wish ask about the PIC16F84A which is 18pin
and from the datasheet, i confuse with the lowest voltage rating of this PIC

PIC16F84A
D001 4.0 - 5.5V XT,RC and LP osc configuration
D001A 4.5 - 5.5V HS osc configuration


Wide operating voltage range:
- Commercial: 2.0V to 5.5V
- Industrial: 2.0V to 5.5V

how to differentiate?and which one is the lowest voltage rating?

 

Looks like it's only the 16LF84A which goes down to 2V.
More modern PICs are a better choice and typically work from 3V-5.5V