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MCU erases its flash memory at higher temperatures

Question asked by Jan Coufal on Nov 12, 2013
Latest reply on Nov 13, 2013 by Jan Coufal

Hello

I was trying to write a service request but it does not work -gives me an error when I am trying to send it . So I am posting it here.

 

We (UNIS company) are using Freescale DSP MC56F8323 and we just observed anomalous behaviour of MCU delivered to our customer.

 

The part of the MCU flash memory starts to lose the information when temperature is above the 65°C. Some memory cells change its values from 0 to 1 (erase state - MCU forget).

The higher temperature is - the more cells are erased.

When temperature drop back under  50°C, all memory cells has their original value (MCU remember)

 

More detail information is, that behavior is observed only in program flash memory, other parts of flash memory does not change with temperature. For programing the MCU, we do not use the default Freescale bootloader, but our own. The used programming process is in accordance with programming process described in chapter 6.5.2 "Write Operation" in MC56F8300UM.pdf

 

 

Anomalous behavior was not observed in our company, but after delivering our unit (with the MCU) to customer.

Now, we are trying to figure out, what could cause this behavior.

Our suspicion is, that our customer exposed the MCU to temperature higher than 125°C.

 

We have following questions:

1) Could this anomalous behavior of MCU be caused by exposure the MCU flash memory to temperature higher than 125°C?

 

2) Do you have an idea, what anomalous behavior could be caused, if not temperature?

 

3) Other units in delivered batch were probably exposed to higher temp as well as the problematic one, but they are functional. We did not observed any anomalies in behavior on them, but If answer to question [1] is "yes" , then the question is: Can service life or reliability of exposed units be affected?

 

4) Can service life or reliability of exposed units deteriorate within time?

 

5) Do you have customers who observed similar problem?

 

Thank you

 

S pozdravem / Best regards

 

Jan Coufal

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