i.MX6DQ GPIO DC spec as recognized as High.

[satoshishimoda]

Hi community,

Our customer have a question about i.MX6 GPIO DC parameter.
Please see of Table 22 in IMX6DQCEC.
We understand i.MX6DQ recognizes input signal as High certainly when it is over VIH (0.7 * OVDD) in general.
In addition, i.MX6DQ rarely recognizes input signal as High when it is between VIL (0.3 * VDD) and VIH.

Next, please see footnote 4, it says "Hysteresis of 250 mV is guaranteed over all operating conditions when hysteresis is enabled".
According to these description, our customer guessed that the minimum voltage which is recognized as High is VIL + hysteresis (250mV).

Is this correct?

Or there is a possibility that i.MX6DQ recognizes the input voltage as High if it exceeds VIL only little?

Best Regards,
Satoshi Shimoda

[Yuri]

Hello,

  Strictly speaking, the comment regarding the hysteresis parameter affects only
Schmitt trigger values of 0.5 OVDD. 
High-Level DC minimal input voltage is 0.7 OVDD

and  

Low-Level DC maximal input voltage is 0.3 OVDD.

Have a great day,
Yuri

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[satoshishimoda]

And please note that the reply we want to get is NOT "high = VIH, low = VIL", because we believe "i.MX6DQ rarely recognizes input signal as High when it is between VIL (0.3 * VDD) and VIH.".

Definitely, we understand recognizing the input voltage between VIL and VIH as high is rare case.

So we want to know which of the following is correct.

high = input voltage > VIL.

or 

high = input voltage > VIL + 250mV.

Best Regards,

Satoshi Shimoda

[Yuri · Accepted solution]

Hello,

high = input voltage > VIL, assuming that sometimes input voltage > VIL may be 

recognized as high.

Regards,

Yuri.

[satoshishimoda]

Dear Yuri,

Thank you for your reply.

OK, I understood.

By the way, could you give me reply whether the hysteresis is enabled for POR_B or not also?

Or is it better to request to another post?

Best Regards,

Satoshi Shimoda

[satoshishimoda]

Hello Yuri,

Thank you for your reply, but I have one more question.

I got a reply about POR_B hysteresis in Regarding i.MX6DQ POR_B input. .

As per this post, I understood POR_B pad have hysteresis even though the POR_B input logic is determined by VIH, VIL.

However, as per your reply, they hysteresis affects only schmitt trigger value of 0.5 OVDD.

Which is correct?

Or both are correct and only POR_B pad have the hysteresis other than schmit trigger?

Best Regards,

Satoshi Shimoda

[Yuri]

Hello,

   Parameters VIH and VIL for Schmitt trigger inputs differ from

corresponding parameters of "usual" inputs :

VIH = 0.5 OVDD + hysteresis ;

VIL = 0.5 OVDD - hysteresis

Regards,

Yuri.

[satoshishimoda]

Hello,

So this is my last question.

POR_B has no hysteresis same as usual input pins even though I got the hysteresis value in https://community.nxp.com/thread/433659 ?

Best Regards,

Satoshi Shimoda