What happen in usecase of i.MX6UL+PF3000-A4 series?

[kanoumamoru]

Hi, community.

Our customer made the i.MX6UL custom board with PF3000-A4 + DDR3 (not DDR3L).

Although they made total 10 sets, one i.MX6UL board is broken with over-current issue.

After some investigation, they found that  DDR3 is short-circuited so huge current flows to i.MX6UL DDR3 IO Pads. 

Below picture is thermal photo.

Question:

We know that the power sequence of PF 3000-A4 does not meet the power sequence of i.MX 6 UL.

That is,

In the specification of iMX 6 UL power-up sequence must be VDD_HIGH_IN -> VDD_SOC_IN,

but In PF 3000-A4, power is turned on in the order of SW1B(VDD_SOC_IN) -> V 33(VDD_HIGH_IN).

Is there a possibility that the interface of DDR 3 will be destroyed in this case?

If this answer is yes, why DDR I/F is broken? 

Best Regards,

kanou

[kanoumamoru]

Hi Jose,

Thank you for your advices.

> If I properly understand, the current/short issue can only be seen in 1 of the 10 tested boards, correct?

Yes, you're correct.

I recognized we should be check the soldering processor or DDR.

Best Regards,

kanou

[reyes · Accepted solution]

Hi Kanou,

Using the default power-up sequence of the PF3000A4 should not cause this over-current/short issue by using it with the i.Mx6UL + DDR3, I don’t think that this is the source of the problem.

If I properly understand, the current/short issue can only be seen in 1 of the 10 tested boards, correct?

And all 10 board are using the same components and same configuration, correct?

If the answer for both question above is “Yes”, then I strongly believe that the problem you are seen is related to a manufacture issue or even a low possibility caused due to a bad layout design.

You mentioned that you found a short-circuit on the DDR3, is it possible that this short is caused during manufacture or soldering process?

Have a great day,
Jose

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