on one of our boards we are using the iMX537 which is powerd by the PMIC MC34708, on the PMIC there is a 3V coin cell connected.
Until now we produced approximately 1000 unit without any problem.
With the last batch (250 pieces) there are 12 boards with the following failure :
When the power is applied : VSRTC = 1.3V --> OK
When the power is removed : VSRTC drops down to 0V.
So the connected 3V coin cell doesn't take over to feed the VSRTC supply.
We have replaced the PMIC on 3 boards and the problem is solved, so it looks like the PMIC chips are bad....
Has anybody experienced the same problem ?
Could there be an other reason for that behavior ?
Thanks for the respons