Quote Originally Posted by BobP View Post
I just looked at the maximum ratings for the 18F2525 and it says it can take a max of 7.5 volts!
So running a 2525 from 4 x 1.5v cells should be ok. Check the datasheet for the PIC you are using.
Hi Bob,

The voltage 7.5V is not the maximum operating voltage of the chip.

The 7.5V visible in the "Absolute Maximum Ratings" page 323, is
the voltage where you can go without physical damage to the chip.
The PIC18F2525 will operate reliable only when the voltage is between
4.2V and 5.5V.

This note is visible on page 323:

NOTICE: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent
damage to the device. This is a stress rating only and functional operation of the device
at those or any other conditions above those indicated in the operation listings of this
specification is not implied. Exposure to maximum rating conditions for extended periods
may affect device reliability.

See the datasheet page 326, parameter No. D001 for the operating voltage.

Datasheet:
http://ww1.microchip.com/downloads/e...Doc/39626b.pdf

Best regards,

Luciano