Can TS3USB221 switch I2C Signals? How do you implement I2C pull up resistors using a passive FET switch like TS3USB221

Ivy Ong

Prodigy 230 points

Other Parts Discussed in Thread: TS3USB221

Hi,

I would like to ask if TS3USB221 can be use to switch I2C Signals?

Thanks

over 12 years ago

0 David_Wang over 12 years ago

TI__Intellectual 1465 points

Hi, Ivy,

Sorry for the late reply.

Yes you may use the TS3USB221 to switch I2C signals.

Thanks,
David

0 Sneha Kumari over 8 years ago in reply to David_Wang

Intellectual 300 points

Hi,

I am planning to use TS3USB221 for I2C mux, Do I need to provide pull ups on both sides of the MUX? what do you recommend?

Thank you.

regards,

Sneha

0 Adam Torma over 8 years ago in reply to Sneha Kumari

TI__Mastermind 45340 points

Sneha,

Yes, TS3AUSB221 does not have internal pull ups. When implementing I2C communication with this device, there needs to be pull-up resistors on both the master and slave buses to prevent glitching when switching channels.

This post below shows some other signal switches being used in I2C applications
e2e.ti.com/.../390098

Thank you,
Adam

0 Sneha Kumari over 8 years ago in reply to Adam Torma

Intellectual 300 points

Hi Adam,

Thank you very much.

In our board, channel switching is not done during operation. It is controlled by a switch, and the channel will be selected prior to power on.

Pullups are provided on the 1D and 2D side, but not on the D signals. The artwork is almost finished. Is it mandatory to provide pull up on both sides, since there is no channel switching during operation?

regards,

Sneha

0 Jonathan Valdez over 8 years ago in reply to Sneha Kumari

TI__Genius 16430 points

I want to add that if you use the switches for I2C signaling and have pull-ups on both sides you need to halve the pull-up strength(double the pull-up resistance) since whichever side is driving the bus now has to drive two sets of pull-up resistors.

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Can TS3USB221 switch I2C Signals? How do you implement I2C pull up resistors using a passive FET switch like TS3USB221