TPD12S016: I2C for this chip does not pull down strongly

Michael Misiewicz

Part Number: TPD12S016

Tool/software:

We are seeing the same issue here with this TPD chip.

When the TDP attempts to do the NACK, we see those intermediate voltages (not zero) that vary with the external pullups. Note in our case we have multiple devices on the I2C bus, and this TDP chip is the only one having any issues. Are we to understand the chip is designed to be point-to-point on the I2C bus with no external pullups? I'm about to attach a scope trace showing our issue as well.

over 1 year ago

0 Michael Misiewicz over 1 year ago

Prodigy 30 points

Here is the indeterminate pulldown by the TDS. We have played around with the external pullup resistance and gotten this level to move around, but by calculation it will never go to "zero" for the other chips based on this datasheet spec.

0 Michael Misiewicz over 1 year ago in reply to Michael Misiewicz

Prodigy 30 points

0 Seong Kim over 1 year ago in reply to Michael Misiewicz

TI__Mastermind 46271 points

Hello Michiael,

Is this occurring on one device? Or is the same behavior observed on multiple devices?

BR,

Seong

0 Michael Misiewicz over 1 year ago in reply to Seong Kim

Prodigy 30 points

we have multiple prototypes of the board using this chip, and they all exhibit the same behavior on the a-side SDA SCL lines.

0 Seong Kim over 1 year ago in reply to Michael Misiewicz

TI__Mastermind 46271 points

Hello Michael,

Noted. So you are sayin that the ACK (logic 0) is properly pulled down on the B-side, but it does not get pulled all the way down to ~0V on the A-side, correct? And the controller reads this as a NACK (logic 1)?

BR,

Seong

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TPD12S016: I2C for this chip does not pull down strongly