Revisited: Vcc-AVcc connection on Mega8; 48/88?

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About a year ago there were several threads on a Mega8 flaw whereby Vcc & AVcc were connected internally; only a few ohms between them.

https://www.avrfreaks.net/index.p...

Now that the Mega48 & 88 are here, I was curious as to the "separation" of the supply lines.

ATMega48V-10AI (QFP) has 5.2 MOhms between the pins.

I don't have any Mega88s or other flavours of Mega48 to check them out. Maybe someone could do a quick check on a production Mega88 and report?

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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I have some m88 "engineering samples" date code 0432,
some production m48V10AIs also 0432, and some production
m8820AI, 0448. All seem to have no direct connection between
Vcc and AVcc.

My problem with the 88 right now is that I need guaranteed eeprom
performance at 3.3 volts, and according to the datasheets, the current
version is not reliable. I have a design ready for production that is
on hold until this is fixed.

Tom Pappano
Tulsa, Oklahoma

Tom Pappano
Tulsa, Oklahoma

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I measured a M48 DIP & a M88 DIP

My meter wouldnt even give a reading ....

There vere around 4.8 Mohm between VCC & GND

Is that my meter or a perfect AVR ??

/Bingo

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Quote:

My meter wouldnt even give a reading ....

There vere around 4.8 Mohm between VCC & GND

Is that my meter or a perfect AVR ??

It could have been me, trying to get [relatively] stubby voltmeter probe tips onto the correct TQFP pins when my bifocals wouldn't focus that closely. :)

In any case, I think the summary information is that Vcc and AVcc are indeed separated on the Mega48 & Mega88, so that separate digital and analog supplies are again feasible.

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.