AM6442: SK-AM64B purpose of RC filter

Hello Vaibhav 

Thank you for the query.

Please refer below sections of the data sheet.

7.10.5.9 I2C

7.7.1 I2C Open-Drain, and Fail-Safe (I2C OD FS) Electrical Characteristics

The RC is used to limit the slew.

You could reduce the resistor and increase the resistor.

We have done the implementation in the AM62P SK.

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1340906/faq-am62p-am62p-q1---custom-board-hardware-design---design-and-review-notes-for-reuse-of-sk-am62p-lp-schematics

Refer the FAQ. The FAQ has the AM62P schematics attached with design and review comments.

The RC values has been tested.

Regards,

Sreenivasa

Dear Sreenivasa,
In AM62P schematics, 62E resistor and 100PF capacitor used for a now, where in AM64P schematics 620E resistor and 10PF capacitor used.

Can you please confirm, Is it ok if we use 62E resistor and 100PF capacitor in our costume design for this moment? please guide 

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Vaibhav

Hello Vaibhav, 

Thank you.

einfochips an Arrow Company said:

In AM62P schematics, 62E resistor and 100PF capacitor used for a now, where in AM64P schematics 620E resistor and 10PF capacitor used.

Can you please confirm, Is it ok if we use 62E resistor and 100PF capacitor in our costume design for this moment? please guide 

You should be able to use those values.

Did you have a chance to test with those values?

Regards,

Sreenivasa

Dear Sreenivasa, 

RC filter cutoff frequency is 338KHZ with 4.7K pullup, 62E series resistor and 100pF. and I2C operating frequency is 400KHZ. Thus I2C signal not reach to 3.3V lavel.

We used 4.7K pullup, 62E series resistor and 10pF. and not observer any concern on VIL & VIH. 

Does TI have any concern with 4.7K pullup, 62E series resistor and 10pF? if not then we are ok to go...

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Vaibhav

Hello Vaibhav, 

Thank you.

The concern is the input slew rate.

7.7.1 I2C Open-Drain, and Fail-Safe (I2C OD FS) Electrical Characteristics

Could you please capture the waveform,

Regards,

Sreenivasa

Kallikuppa Sreenivasa said:

Could you please capture the waveform,

Here is reference.

Hello Vaibhav, 

Thank you.

Could you please expand and capture a single pulse to be able to view the falling slew.

Regards,

Sreenivasa

Dear Sreenivasa, 

Kallikuppa Sreenivasa said:

Could you please expand and capture a single pulse to be able to view the falling slew.

Below is requsted data. 

Let me know if you have any consern?

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Vaibhav 

Hello Vaibhav 

Thank you.

Looks to be within the range of the slew rate as per the below section of the data sheet.

7.7.1 I2C Open-Drain, and Fail-Safe (I2C OD FS) Electrical Characteristics

Have you been able to test the interface and do you see it working as expected?

Regards,

Sreenivasa

Kallikuppa Sreenivasa said:

Have you been able to test the interface and do you see it working as expected?

Yes interface is working, 

if TI don't mind then update EVM according to above conversation.

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Vaibhav

Hello Vaibhav 

Thank you.

I will provide the feedback.

I do not have a timeline for the updates or confirmation on the plan.

I can update you when i hear back.

Regards,

Sreenivasa