mpc8315e temperature related problem

[duzhenhuan]

I'm testing a MPC8315E board according to EN 50155.
In normal temperature (25 degree) , the board worked.
The board now have just CPU and NOR FLASH , test program is U-boot LED blinking.

1) During low temperature cooling test, CPU will not start up at -25 degrees after cooling for a while.
But If I power on 1.0V before 3.3V supply, then CPU can stat up and run.

2) During high temperature running test, CPU hang at about 50 degrees after running for a while.
Also, If I make hot air to CPU separately, it also can hang and stop running.
If i Make hot air to other parts separately, such as oscillators and NOR flash, CPU can run.

all parts are industrial grade which can work from -40 to 85.

what can be the possible reason for the problem?Thank you .

 

[chuckey]

Have you actually measured the temperature on the CPU with temperature sensitive strips? What does the 1.0V power?
Frank

 

[duzhenhuan]

Have you actually measured the temperature on the CPU with temperature sensitive strips? What does the 1.0V power?
Frank

temperature is OK.
Development board from Freescale works without any problem.
Can it be related to EMC problem ?