No chip select signal from MPC8245 for flash memory.

[mavillo]

Hi.

We have troubled in our mass production board using MPC8245 which are no boot at irregular case.

1. The number of production

    - 100-set

2. The number of boot failure board

    - 7-set (but all these boards have opeated in some irregular cases. If we try to boot test 10 times, then these boards are boot without any problems 1~9 times.

3. Our Test List

    1) Power Level

         - 5V, 3V, 1.8V : OK.

    2) Reset Signal : OK.

    3) Oscillator : OK.

    4) Chip Select Signal

         (1) NOK.

         (2) In case of boot failure, there are no chip select signals from MPC8245.

    5) Power Sequence

         (1) AC Input(220V, 60Hz) => Switching Power Supply => 5 V Output

         (2) 5V Input => Switching Power Supply => 3.3 V Output

         (3) 3.3 V Input => Switching Power Supply => 1.8 V Output

         (4) But the ramping up of 3.3 V Output is more slow than 1.8V.

We ask answers or opinions about our problem explained above.

[Hector_Villarruel]

Dear Mavillo,

We suspect that the problem is on the hardware and is more related to the manufacture procedure of the card.
Since you have 93 that work, it is not software.

I recommend you to check the power supply of your chip, in the part of the Chip Select, the one that supplies power to the Chip select, to see if any of the capacitors in there is out of range and is causing this problem.
I attach a reference image of the capacitors that you can find in the power supply of your chip.

Best Regards,

Hector Villarruel