TCA9517: The reason of figure 6 waveform

Yusuke Mukuno

Expert 7395 points

Part Number: TCA9517

Hi expert,

Quick question.

Could you please let me know the reason of figure 6 waveform?

Why will the input voltage be constant voltage around 0.4V?

Thanks

Muk

over 3 years ago

+1 Tyler Townsend over 3 years ago

TI__Mastermind 48738 points

Hi Muk,

This is normal and expected behavior when you are driving the B-side of the device, and then releasing. This voltage step is a byproduct of how static voltage buffers operate. The B-side of the device waits until the A side reaches above a certain threshold voltage before it releases.

This question was also referenced in another E2E post here:

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/826159/tca9517-q1-i2c-signal-of-b-side-input-waveform-question

This application note is also a good read to understand I2C buffers:

https://www.ti.com/lit/an/scpa054/scpa054.pdf

Regards,

Tyler