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PMIC MC34708 : VSRTC not OK with coin cell connected and power OFF

Question asked by johan malfait on Jun 10, 2014
Latest reply on Jun 12, 2014 by igorpadykov


in an application we use the iMX537 MCU which is powerd by a PMIC MC34708. Until now we produced a 1000 boards without any problem.

With the last batch of boards (250 pieces) we have a problem on 10 boards with the coin cell back up.

There is a 3V coin cell connected to the PMIC.

When the power is applied (BP = 3.8V) VSRTC = 1.3V --> OK

When the power is removed and the cion cell has to take over, VSRTC drops down to 0V.

We have replaced the PMIC on 3 boards and the problem was gone.

That looks like the PMIC is bad, has anybody experience the same problem ?

Could there not be an other reason for that behavior ?