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Two ATtiny406 dead within a month????

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satyamfifa:
Hello All,

I decided to do a project based on ATtiny406 and last month I ordered 5 prototypes. The ATtiny406 on the first prototype lasted just for about one week, after which it would no longer would program with error: "Framing Error", so I dismissed it as a fluke.

However, after one month the ATTiny406 on the second prototype also stopped programming with error "PDI physical timed out. (25)", of course changing to high voltage UPDI doesn't do anything. Although the microcontroller seems to function normally (UART and Timers are working but it just won't program).

So now I am puzzled I don't know what could be killing these ATTinys.

Also, it's worth mentioning that System VCC is 5.4V, although I don't know why this should be a problem.

Kind Regards,

Sparsh

Update: Three Chips are now dead

Update: more information: The first chip died within a week of testing as I am developing the firmware, the code is uploaded to chip several times, the first chip died with "framing error" and showed impedance of 13k ohm on the programming pin, the second chip lasted for over a month, I might have programmed it like 20 to 30 times at least until finally yesterday I could no longer program it all of a sudden and it gave the error "PDI physical timed out. (25)" but the impedance on the programming pin is normal about 47k ohms, the third chip died today it only lasted less than 24 hours, and I get the same error on this one “framing error” as with the first one, only again the impedance of the programming pin is low about 13k ohms,

Also, it's worth mentioning that at the time second one died I was continuously connecting and disconnecting the programmer as well connecting and disconnecting the power to the board.

Update: Almost Full schematic

ibb.co/09BQ8Vz

Update: Full schematic attached in PDF format

amyk:
How many times have you been programming them?

Psi:
How does the circuit get connected to a programmer when its time to get programmed?

Is it possible your programmer or device has some mains earth voltage leakage that is being shorted when the programmer is connected?
It may only be a tiny amount of current but if the voltage is high it may blow the input.

If the ground connection between the two is made first then it's fine, but if the programming pin connection is made first you can have issues.

Check the voltage on a DMM between the grounds of both systems. (AC and DC)

pcprogrammer:

--- Quote from: satyamfifa on December 06, 2022, 06:18:32 am ---Also, it's worth mentioning that System VCC is 5.4V, although I don't know why this should be a problem.
--- End quote ---

Not criticizing, but why the 5.4V? Sure the ratings for the used chips are 5.5V, but it is pushing the limits, and most designs use 5V, or nowadays a lot is even 3.3V.

Also not saying that it is the root of the problem, but with this high supply and the protection diodes spikes might go over the absolute max rating of 6V and do some damage.

Psi:

--- Quote from: pcprogrammer on December 07, 2022, 07:47:50 am ---
--- Quote from: satyamfifa on December 06, 2022, 06:18:32 am ---Also, it's worth mentioning that System VCC is 5.4V, although I don't know why this should be a problem.
--- End quote ---

Not criticizing, but why the 5.4V? Sure the ratings for the used chips are 5.5V, but it is pushing the limits, and most designs use 5V, or nowadays a lot is even 3.3V.

Also not saying that it is the root of the problem, but with this high supply and the protection diodes spikes might go over the absolute max rating of 6V and do some damage.

--- End quote ---
They are 5.5V max operating and 6V absolute max.
I wouldn't have expected 5.4 to cause any issues like this. (Assuming its stable 5.4 and not 5.4 with bursts up to 6V)

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