Question, SPI port of i.MX25 goes to float

[SLICE]

Dear team,

My customer is using MCIMX257CJM4A for their system.

And they found sometimes a port (D4) of i.MX25 comes to leave floating on their board.

The port is typically used for SPI connection(RXD) with NOR FLASH on their board and sometimes it goes to floating.

And they think that this may increase power consumption of i.MX25 for their board.

If you have any other concerns on this, please let me know.

Thanks,

Miyamoto

[igorpadykov]

Hi Miyamoto

to avoid floating one can configure pin with pull-up, using IOMUXC_SW_PAD_CTL_PAD_x

register. If this is one board one can consider bad contact issue or chip damage during

manufacturing and replace it.

Best regards
igor
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[SLICE]

Hi igorpadykov‌

Thanks for your prompt reply.

The customer estimates that the floating leads to increase of power consumption but not cause the chip damage.

Is it true?

I think you meant that it causes chip damage.

Could you show me the concrete thing on the chip damage?

Best Regards,

Miyamoto

[SLICE]

Hi igorpadykov‌

In general, I think the floating of input port causes through-current.

And the through-current might cause latch-up.

Then the latch-up causes large electrical current.

Then the port might be broken by the large current.

I think the general scenario as above might be applied also to i.MX25.

Correct?

Best Regards

[igorpadykov]

Hi Miyamoto

>The customer estimates that the floating leads to increase of power consumption

>but not cause the chip damage. Is it true?

yes, provided that input signal does not violate requirements described in

Table 20. GPIO DC Electrical Characteristics i.MX25 Datasheet
https://www.nxp.com/docs/en/data-sheet/IMX25CEC.pdf 

Best regards
igor