In reference to a CPU board equipped with NXP MPC5125YVN400 we found a malfunction at startup reset (PORESET)
The problem involves the boards equipped with processor with marking code QAT1535C.
Currently no problem are found on boards equipped with processor with marking code DAR1532AF.
Extending the reset time from 180mS up to 220mS (or more) the problem disappear; --> consider that the datasheet don't impose any constraint regarding the PORESET timing (Obviously is requred that PORESET can be released after all the supplies reach the specified operating conditions).
Enclosed you find some oscilloscope screenshot
Thank You nn advance
Luigi
Usually similar behavior detected if the following happens on the board:
power supply is not stable,
the MPC5125 PLL is not locked
the MPC5125 reset configuration incorrectly read.
Look at the Figure 5 of the MPC5125 Datasheet.
Is there the same behavior of the HRESET and SRESET on your board during power up?
Look at the Figures 51 and 52 of the MPC5125 Datasheet.
Do you use similar connection on your board?
If the second short PORESET is solution of your problem, power supply is not stable or the MPC5125 PLL is not locked during 182ms.
Have a great day,
Pavel Chubakov
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