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[on:]

I was looking at Digikey pricing to get a parts list/price list together and looking at price kit options or something, thinking offer a lesser priced kit with a lower memory part for someone that wanted a data logger with dual serial but didn't need huge amounts of memory for a sketch.
Now, I'm a pretty smart guy, and I know how to read data sheets, but I can't for the life of me figure out what these variations mean on the part numbers.
I am guessing they have to do with screening as the price goes up.  I don't see any explanations, and the graphs in Section 28 all look numbingly the same.

These are all 40 pin DIP parts, 20 MHz, dual serial, 3 interrupts, -40C to +85C operation

164A-PU, $4.75    16K Flash, 0.5K EEPROM, 1K RAM
164PA-PU, $5.21
164P-20PU, $5.60  << not on datasheet
164P-20PQ, $5.77  << not on datasheet

324A-PU, $5.36     32K Flash, 1K EEPROM, 2K RAM
324PA-PU, $5.88
324P-20PU, $7.16  << not on datasheet

644A-PU, $6.45     64K Flash, 2K EEPROM, 4K RAM
644PA-PU, $7.50
644-20PU, $7.98  << not on datasheet
644P-20PU, $8.19  << not on datasheet
644P-20PQ, $8.36  << not on datasheet

1284-PU, $7.33     128K Flash, 4K EEPROM, 16K RAM
1284P-PU, $8.13

Anyone have an explanation?

[Reply #1 on:]

164A-PU, $4.75    16K Flash, 0.5K EEPROM, 1K RAM
164PA-PU, $5.21

...I think a "P" in that position indicates "picoPower".

[Reply #2 on:]

164PA-PU, $5.21
164P-20PU, $5.60  << not on datasheet

...In the ATtiny family, a number in that position indicates maximum clock speed (dash 10 is 10MHz / low voltage range; dash 20 is 20MHz / high voltage range).

Looks like we're both confused.  DigiKey has "picoPower™ Technology" attached to the "-20" processor and the non-20 processor has an extended voltage range "Voltage - Supply (Vcc/Vdd)   1.8 V ~ 5.5 V" versus "Voltage - Supply (Vcc/Vdd)   2.7 V ~ 5.5 V".

[Reply #3 on:]

I looked at all of them for typical current draw in Active condition at 5V - there was no difference between A and PA, or 1284 and 1284P.
I looked at atmel.com for picopower, no joy there either.

[Reply #4 on:]

At Mouser, this... ATMEGA164P-20PU ...has this... Operating Supply Voltage: 4.5 V to 5.5 V
But this... ATMEGA164P-20PQ ...has no voltage range specified.

There is NO explanation of "Q" in that datasheet.

[Reply #5 on:]

as it happens I just stumbled across this list in an earlier thread....

all the variants and then some

[Reply #6 on:]

I believe that the PicoPower chips are ones that will run at exceptionally low voltage levels for a given clock speed, hence consuming less power.

For our purposes it doesn't matter much, as we're using a full 5v even if we don't need to do so to get the clock speed up.
I suspect the PicoPower chips would have an easier time running at 16/20mhz at 3.3v though.

[Reply #7 on:]

From mmcp42's link, I was able to find this app note on picoPower:
http://www.atmel.com/dyn/resources/prod_documents/doc8349.pdf

The things they did to conserve power while running off a charged capacitor (simulate a battery, but with a controlled source) were able to extend the running times by a lot!  Some things have been discussed in the forum, others not, resulting in a greater than 36x increase in runtime:

"In this example, the runtime was increased from 6 to 217 seconds running off the same power source."

Gonna see what else I can find ...

[Reply #8 on:]

I looked at the 164s, 324, 644s, and 1284s.
The only thing I see different is that parts without P don't have picoPower.
And the straight 644 only has 1 UART.
No explanation of what the Q means.

[Reply #9 on:]

The letters BEFORE the dash are (usually) part of chip type.  "A" implies a die shrink since the original release, "P" means picopower.  There's pretty much a separate datasheet for each combination of letters before the dash (separate datasheet for ATmega644P and ATmega644PA.)  The letters AFTER the dash designate the packaging, which will normally be described in the "Ordering information" section of the datasheet.

So the atmega644P datasheet says that 644P-20AU is a TQFP-44, -20PU is a DIP-40, and -MU is a QFN-44
The 644PA datasheet add a couple packages but is basically the same.  I couldn't find a -20PQ anywhere :-(

[Reply #10 on:]

..."A" implies a die shrink since the original release,...

I think I read on avrfreaks that the 'A' signifies a change in die supplier.  The die shrink was a result of this change in supplier but may or may not have been the stimulus for the change.

Don

[Reply #11 on:]

Ok, So consensus is A is a different die somehow.
Q still the mystery letter! Only seems to affect price, so must be some extra screening thing.

[Reply #12 on:]

If this is still accurate...

http://www.nalanda.nitc.ac.in/industry/datasheets/atmel/acrobat/doc0538.pdf

...the "Q" is a temperature code.  Which begs the question... Where in that list does "Q" fall?

[Reply #13 on:]

Ok, So consensus is A is a different die somehow.

But sometimes it also can mean additional features and maybe not a die shrink ? Like second serial port for 644p Vs 644.

I would be interested in if there is a way to determine if the internal device codes (used by AVRDUDE) are different between the different 'flavors' of chips within a family. Does Atmel have a single document where device numbers Vs internal device codes is shown? AVRDUDE has those codes listed in it's avrdude.conf file, but where did they find this information?

Lefty

[Reply #14 on:]

No, I think that says Q is Quad Flatpack

164P-20PQ
644P-20PQ

Makes one really wonder if these 2 part #s are hosed, or if Q is some undocumented Temperature Range.

Looks like P and PA devices are the way to go tho:
2006: http://www.atmel.com/dyn/resources/prod_documents/doc8038.pdf
2009: http://www.atmel.com/dyn/resources/prod_documents/doc8190.pdf