SD card leak voltage with i.MX6Q.

[keitanagashima]

Dear Sir or Madam,

Hello.

My customer wants to keep only VDD voltage for SD card during 256 ms, to prevent data destruction at the power off.

(i.e. NVCC_SD is Low. VDD voltage was kept for 256 ms)

But, because DATA3 of SD card has internal pull-up, the leak voltage occurs via SD_DATA3 and NVCC_SD line.

There are possibility that the leak voltage occurs about SD_DATA3=700[mV] and NVCC_SD=150[mV] during power off to 256ms by customer's measured data on the their past i.MX6 product.

*Refer to attache file.

[Question]

If the system drops on 0[V] by next time power on, is there possibility of the latch-up of i.MX6?

Best Regards,

Keita

[art · Accepted solution]

The i.MX6 Series Hardware Development Guide document states that no I/O signals of the processor should be driven by any external voltage when the corresponding NVCC_xxx supply is powered off. So, the solution, implemented by your customer, is not allowed. The better way seems to properly shut down a SD card in software before powering off the whole system.

Have a great day,
Artur

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