# i.MX 8M Plus Timing parameters

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## i.MX 8M Plus Timing parameters

1,093 Views
Contributor IV

Hi there,
I'm missing some information in the current i.MX 8M Plus datasheet IMX8MPIEC Rev.1):

I looked for "ECSPIx_SCLK Rise or Fall" time in table 36 - which references to section 3.5 (I/O AC parameters).
In figure 8 I can find the necessary tr and tf markers. However, if you search within the document, there are no actual numbers listed anywhere in the datasheet. So what values do I have to expect here?

According to table 36 I would expect some minimum and/or maximum values, but I can't extract any of those from the datasheet. Can you please provide some information on that?

Thanks in advance.

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11 Replies
642 Views
NXP TechSupport

Hello @florian_arndt, here Jorge.

Here is an update from the internal team.

As it has indicated in the datasheet, the Tr and Tf value shall refer to Section 3.5.

According to Section 3.5 description shown below, the Tr and Tf depend on the load capacitance (CL) on the IO and its drive strength (output resistance).

According to the RC charge/discharge circuit and equation shown below, the rising and falling time between 20% and 80% OVDD is [Tr = Tf = 1.39RC], where R is the output resistance and C is the load capacitance (CL).

According to the Drive Strength setting and its corresponding output current table shown below, the minimum output resistance of the IO at Fast slew rate mode is around [(1.8V / 10.5mA + 3.3V / 20.6mA) / 2 = 165Ohms] and the maximum output resistance of the IO at Fast slew rate mode is around [(1.8V / 5.27mA + 3.3V / 10.3mA) / 2 = 330Ohms].

Suppose the load capacitance is 50pF, the minimum Tr and Tf would be [Tr = Tf = 1.39 x 165Ohms x 50pF = 11.5ns] and the maximum Tr and Tf would be [Tr = Tf = 1.39 x 330Ohms x 50pF = 23ns].

Best regards.

969 Views
NXP TechSupport

Hello, here Jorge.

The internal team asks for:

What is prompting you to ask about the timing parameters?

This question is because there are no information about this and is going to take time to give an answer.

Best regards.
Jorge.

963 Views
Contributor IV

Hello @Jorge7u7,

first of all: I have to do qualification work for a project with SPI communication. Therefore I need values to verify.
Second: Consistency - see the original post of this thread. Why would you provide diagrams without any values for some explicitly named parameters (= rise and fall times)?

And also just to repeat my words from this thread: This topic not only belongs to 8M Plus but to 8M Mini and 8M Nano datasheet as well.

Thanks in advance.

980 Views
NXP TechSupport

Hello, here Jorge.

Right now we are working on this case on the internal community and this will take a while so, I will send the information of the internal team as soon as possible.

Best regards.
Jorge.

915 Views
Contributor IV

Hello @Jorge7u7,

any news on this topic?
Thanks.

882 Views
NXP TechSupport

Hello @florian_arndt, here Jorge.

The internal team still working on this case, I will send you any update when the internal team send a response.

Best regards.

1,079 Views
NXP Apps Support

@Jorge7u7 can you comment here?

1,075 Views
NXP TechSupport

@karina_valencia Sure, I will comment here when we have the missing information.

Best regards.
Jorge.

1,033 Views
Contributor IV

Good morning @Jorge7u7,

are there new information available?

Thanks for an update in advance.

1,019 Views
NXP TechSupport

Hello, here Jorge.
Thank you for your time.

We are waiting for information of the internal team. I will send you the response as soon as possible.

Best regards.
Jorge.

1,084 Views
Contributor IV

Hi there,

I also tried to look up the same values in datasheets of 8M Mini and 8M Nano but with the same phenomenon:
There are no rise or fall times given in chapter "I/O AC parameters". Am I the first one who wants to know these?

Can someone help me with this request, please? Maybe @karina_valencia?

Thanks in advance.

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