Regarding i.MX6DQ POR_B input.

[satoshishimoda]

Hi community,

Our customer have a question about i.MX6 POR_B.
They know the restriction "SRC_POR_B rise/fall times must be 5ns or less" to POR_B slew rate have been removed from datasheet (IMX6DQCEC Rev.4).
So they understand there is no restriction to POR_B slew rate, and there is input hysteresis to prevent chattering.
Is their understanding correct?

If correct, would you let me know the input hysteresis spec?

Best Regards,
Satoshi Shimoda

[igorpadykov · Accepted solution]

Hi Satoshi

hysteresis is 250 mV according to Table 22. GPIO I/O DC Parameters

i.MX6DQ Datasheet

http://cache.freescale.com/files/32bit/doc/data_sheet/IMX6DQCEC.pdf

Best regards
igor
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[satoshishimoda]

Dear Igor,

Thank you for your prompt reply.

OK, I understood about hysteresis.

And would you give us your reply whether the following our customer's understanding is correct or not also?

"So they understand there is no restriction to POR_B slew rate"

In fact, the POR_B slew rate on their custom board is very slow.

About 500ms is needed to rise the POR_B from 0V to VIH (2.1V).

They think it is OK since the restriction has been removed from datasheet.

Is it OK? or faster slew rate is required?

Best Regards,

Satoshi Shimoda

[igorpadykov]

Hi Satoshi 

please refer to footnote 3 Table 22 :

To maintain a valid level, the transition edge of the input must sustain a constant slew rate (monotonic) from the current DC
level through to the target DC level, Vil or Vih. Monotonic input transition time is from 0.1 ns to 1 s.

So seems 500ms is ok.

Best regards
igor