TCA9535 - I2C rise/fall time requirement

Kawai

Guru 19775 points

Other Parts Discussed in Thread: TCA9535

Hi Team,

Please allow me to ask you about the switching characteristic spec for TCA9535. For input rise/fall time, TCA9535 datasheet spec is specified based on Fast mode.
In the I2C specification, Standard mode rise/fall time does not have minimum value specification.

[Q1]
Does this mean that rise/fall time can be lower than 20ns at Standard mode, for I2C specification ?

[Q2]
How about the requirement for TCA9535 I2C standard mode ? Does rise/fall time must be larger than 20+0.1Cb ?

I also had my similar post, however, please let me confirm about these questions.

https://e2e.ti.com/support/interface/etc_interface/f/390/p/400173/1415813#1415813

<TCA9535 Datasheet>

<I2C specification>

Best Regards,

Kawai

over 8 years ago

0 Jonathan Valdez over 8 years ago

TI__Genius 16430 points

Hello Kawai-san,

This is a mistake in our datasheet. We put the fast-mode settings in there, and did not put another entry for the standard mode. The TCA9535 is fully compatible with I2C standard speed per the I2C spec that you posted. These values come from the I2C spec, we made a mistake when entering them.

0 Kawai over 8 years ago in reply to Jonathan Valdez

Guru 19775 points

Hello Jonathan-san,

Could you please let me confirm one thing about the I2C spec ?

As there is no description for MINIMUM tr or tf spec, I believe there is no limit. Our customer's measured tf is 5ns at standard mode.
Can you say this is still complying I2C spec ? Does TCA9535 has any problem using in this case ?

Best Regards,
Kawai

0 Jonathan Valdez over 8 years ago in reply to Kawai

TI__Genius 16430 points

You are correct. There is no defined minimum tR or tF.

You should have no issues with a tF of 5ns.

0 Kawai over 8 years ago in reply to Jonathan Valdez

Guru 19775 points

Jonathan-san,

Thanks for your answer!!

Best Regards,
Kawai

Interface

Interface forum

TCA9535 - I2C rise/fall time requirement