TCA4311: "I2C write failed" issue reported occasionally

Rannie Zhou

Part Number: TCA4311

Tool/software:

Hi team,

My customer is using TCA4311 in their system paired with TCA9548. They meet the "I2C write failed" issue in their system occasionally w/ TCA4311.

Issue signature:

TCA9548+TCA4311 connection:

With TCA4311, the waveform of passing and when failed:

pass:

fail:

If they remove TCA4311 and connect SMBUS, there will be no write fail problem.

Why does TCA4311 affect the operation of the SMBUS bus?

BRs,

Rannie

8 months ago

0 Clemens Ladisch 8 months ago

Guru 318760 points

Please show a proper schematic, including all I²C signals and pull-up resistors. And the clock signal looks strange; please use a higher sample rate.

0 Rannie Zhou 8 months ago in reply to Clemens Ladisch

TI__Expert 4660 points

Hi Clemens,

Adding the sch:

Brs,

Rannie

0 Clemens Ladisch 8 months ago in reply to Rannie Zhou

Guru 318760 points

This schematic does not show any pull-up resistors on the NMC_SMBCLK/DAT lines.

Please show an oscilloscope trace with both NMC_SMBCLK and NMC_SMBCLK_OUT.

0 Tyler Townsend 8 months ago in reply to Rannie Zhou

TI__Guru 53258 points

Hi Rannie,

In the passing and failing condition, is it possible to capture both sides of the buffer?

Please try to capture all 4 signals SDAIN + SDAOUT + SCLIN + SCLOUT.

Regards,

Tyler

0 Rannie Zhou 8 months ago in reply to Tyler Townsend

TI__Expert 4660 points

Hi Tyler and Clemens,

We probe with Logic analyzer and found that there is an external clock signal like below:

0 Clemens Ladisch 8 months ago in reply to Rannie Zhou

Guru 318760 points

Please probe with an oscilloscope. It is possible that the edges are too slow or that you have noise.

0 Tyler Townsend 8 months ago in reply to Rannie Zhou

TI__Guru 53258 points

Hi Rannie,

I second Clemens here.

Can we gather analog waveforms using o-scope?

Regards,

Tyler

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TCA4311: "I2C write failed" issue reported occasionally