uController Suffixes..

I’ve noticed that many different Microcontrollers have different “variations”, or so I assume, listed in their suffix.

I’m currently looking at the ATmega644. On digikey, there are 4 different kinds of DIP 644 listed:


Does anyone know the differences? :open_mouth:

I saw a good deal on a couple of 644s for my “GhettoDuino644”, but they are the “644-20PU”, and not the “644P-20PU” used in other 644 clones I’ve seen. Would that matter?

All of the chips specs seem to be the exact same, other than the fact that the middle two are 20 cents more expensive…

Help please! :smiley:

The best answer I can give you from looking at things is that the ones that cost 20 cents more have some kind of extra “power saving” mode; I am not sure what this mode does, but it seems different from sleep and low power modes.

Maybe someone else can shed some light; you might also try contacting the sales department of Atmel and asking them to explain the options.

The PV is specified for 4MHz at Vcc=1.8V and 10MHz for Vcc=2.7-5.5V.
The P is specified for 10MHz for Vcc=2.7-5.5V and 20MHz at Vcc=4.5V-5.5V.

I believe that the 644 has a single UART versus two for the 644P.
I am not sure if there are other differences between P and non-P.

Unless you are running at voltage levels below 2.7V I would go with
the ATmega644P.

(* jcl *)

I could easily be wrong but I believe…

The “P” in ATMEGA644P and ATMEGA644PV indicates this…

The “V” in ATMEGA644PV and ATMEGA644V indicates a “low voltage” (or extended voltage) processor.

The “10” indicates a maximum clock speed of 10MHz.

The “20” indicates a maximum clock speed of 20MHz.

I have no idea what the “PU” signifies.

I have no idea what the “PU” signifies.

Package and temperature range, I think. “P” means the 28pin 0.3inch DIP, and “U” means lead-free RoHS compliant “industrial temp range”. (PI would be lead-containing.)

This is usually covered by the “Ordering Information” section of the chip’s datasheet.

I’ve carefully looked over datasheets for at least six processors and never noticed that section. [smiley=embarassed.gif] Thanks for the tip!

   Ordering Code      Package
   ----------------   -------
   ATmega324PV-10PU   40P6
   ATmega324P-20PU    40P6
   Package   Description
   -------   -------------------------------------------------------
   40P6      40-pin, 0.600” Wide, Plastic Dual Inline Package (PDIP)

Even though the datasheet doesn’t specifically indicate, this presumably is the footnote for “U”…

Pb-free packaging, complies to the European Directive for Restriction of Hazardous Substances (RoHS directive). Also Halide free and fully Green.

Oh, cool!

So, the ATMEGA644-20PU would work fine, and the only difference is the picoPower and the low voltage? Those should both not matter, as I wasn’t planning on using picoPower, and I was going to make this a 5V board.

So, the ATMEGA644-20PU would work fine,

Don’t forget that the 644P has two UARTs and the 644 only one.
This may not matter in your current application but it
could be useful in the future.

I learned this suffix lesson the hard war :wink:

(* jcl *)

Oh yes, I forgot about the UARTs.

That would be nice to have, but it probably won’t matter (this is just another prototyping board I plan on making).