topic Re: i.MX6DQ IOL for I2C. in i.MX Processors

i.MX6DQ IOL for I2C.

satoshishimoda — Thu, 25 Dec 2014 00:43:24 GMT

Hi community,

Our partner want to know the IOL (Low-level output current) of i.MX6DQ pad for I2C I/F.

I guess, it satisfies the I2C specification which is written in Table 9 of UM10204 (NXP, I2C bus specification and user manual) as attached image.

Is this correct?

Best Regards,

Satoshi Shimoda

Re: i.MX6DQ IOL for I2C.

Yuri — Thu, 25 Dec 2014 05:15:10 GMT

We do not provide separate DC hardware specs for i2C signals in our i.MX6 Datasheet(s),
assuming common GPIO DC parameters for it. Values of load current in the Datasheet(s)
relate to some typical configurations, in particular - in order to guarantee specified output
voltages. For more accurate (application depended) estimations IBIS models should be applied.
I looked at i.MX6 IBIS – it meets the mentioned NSP specs.

Have a great day,
Yuri

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Re: i.MX6DQ IOL for I2C.

satoshishimoda — Thu, 25 Dec 2014 09:29:47 GMT

Hi Yuri,

Thank you for your reply.

> it meets the mentioned NSP specs.

I think it is typo of "it meets the mentioned NXP specs.", right?

Best Regards,

Satoshi Shimoda

Re: i.MX6DQ IOL for I2C.

Yuri — Fri, 26 Dec 2014 04:56:59 GMT

Correct - NXP.

~Yuri.

Re: i.MX6DQ IOL for I2C.

satoshishimoda — Tue, 06 Jan 2015 07:56:12 GMT

Hi Yuri,

OK, I got it.

Then, I have one more question.

> I looked at i.MX6 IBIS – it meets the mentioned NSP specs.

How did you judge whether it meets the NXP specs?

I don't know how to confirm IOL by IBIS, so would you let me know it?

Best Regards,

Satoshi Shimoda

Re: i.MX6DQ IOL for I2C.

jamesbone — Wed, 14 Jan 2015 16:37:18 GMT

YuriMuhin_ng, Can you please follow?

Re: i.MX6DQ IOL for I2C.

Yuri — Thu, 15 Jan 2015 04:50:03 GMT

The i.MX6 DQ IBIS file may be found on the Web.

https://www.freescale.com/webapp/Download?colCode=IMX6_DQ_IBIS&appType=license&location=null&fasp=1&WT_TYPE=IBIS&WT_VENDOR=FREESCALE&WT_FILE_FORMAT=zip&WT_ASSET=Downloads&fileExt=.zip&Parent_nodeId=1337637154535695831062&Parent_pageType=product

Summary Page :

http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=i.MX6Q&fpsp=1&tab=Design_Tools_Tab

Next, please refer to Chapter 9 (Understanding the IBIS Model) of “Hardware Development Guide
for i.MX 6Quad, 6Dual, 6DualLite, 6Solo Families …”

http://cache.freescale.com/files/32bit/doc/user_guide/IMX6DQ6SDLHDG.pdf

IBIS provides V-I curve, where data is presented as a table of current measurements, taken at a
series of output voltages that covers a range of –Vcc to +2Vcc. According to the IBIS Voltage
Convention, the voltage in the table for pullup and power clamp curves is:

Vtable = Vcc - Voutput

And, is therefore, the voltage across the pullup circuit referenced to Vcc and not to ground, by convention.
At the same time, the pulldown curves are normally referenced to ground. The range –Vcc to +2Vcc is chosen
because those are the limits of the voltage swings that can be seen on a transmission line with high reflection
(high mismatch) coefficients when switching a driver from Vcc high state to 0 V low state.

So, let’s consider the V-I curve of “gpiohv_ds111_sr101_mio” model in file “21x21_imx6q_consmr_004.ibs”.
In pulldown section - to estimate the IOL (in open drain, sink current) – current of ~50 mA can be gotten.

~Yuri.