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PIC18F26K20 operating voltage

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tubos

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I have a hardware project running with a 16F886 powered by a LI ION battery at maximum 4.2V I'd like to drop in a PIC18F26K20 for increased ram.

I noticed in the datasheet it is normally for 3.6V the absolute maximum ratings for pins are 4.5v. Will i Hurt this pic when i continually power it at 4.2v dropping to 3.5v when the battery is low?

Is it correct I do not have to bank switch for accessing all the ram on this 18F... ?
Any other things I need to watch?
 
You could damage it. Just fit a low drop regulator.

You often need to bank switch on the 18F series, because the instructions have only 8 bits of register address in them, so they can only access 256 locations, or 512 if you include the access bit.

See figure 5-8 of https://ww1.microchip.com/downloads/en/DeviceDoc/41303G.pdf

The indirect addressing uses the indirect addressing registers, which are 12 bit registers. They can be loaded in one go with the LSFR command (although that command is 2 lines long and takes 2 cycles). Then you can use POSTINC0 etc to access all of the memory, if you want to do it that way.
 
I noticed in the datasheet it is normally for 3.6V the absolute maximum ratings for pins are 4.5v. Will i Hurt this pic when i continually power it at 4.2v dropping to 3.5v when the battery is low?

The data sheet tells you can use it at 4.5 volts and it will work but the life of the chip will go way down. Your better doing like Diver300 and drop the voltage down
you can drop it .6 volts with diode
 
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