TCA9554A: Regarding the issue where the TCA9554A does not return an ACK to the register address

Kyohei

Part Number: TCA9554A

Hi team,

My customer is considering adopting the TCA9554A and is currently evaluating it on their board.

During the evaluation, we encountered a situation where the device does not return an ACK to the register address on the evaluation board.

I have attached the waveforms for both the normal (OK) operation and the abnormal (NG) operation for your review.

Normal operation waveform

Abnormal operation waveform

One point of concern is that, in the abnormal waveform, the timing of SCL and SDA appears almost identical. We suspect this may be causing the malfunction. Could you please review the waveforms and advise on the possible cause?

Best regards,

Kyohei

8 months ago

0 Tyler Townsend 8 months ago

TI__Guru 65698 points

Hi Kyohei,

What changes on the EVM setup between the two scope captures, or is this fail-mode periodic?

Regards,

Tyler

0 Kyohei 8 months ago in reply to Tyler Townsend

Genius 3141 points

Hi Tyler-san,

Thank you for your support.

The changes observed between the two waveforms correspond to a device change.

Currently, eight devices are in use, and six of them exhibit the waveform in which the operation fails.

Best regards,

Kyohei

0 Tyler Townsend 8 months ago in reply to Kyohei

TI__Guru 65698 points

Hi Kyohei,

Do you have a top-side marking photo of a working and suspected fail device?

Regards,

Tyler

0 Kyohei 8 months ago in reply to Tyler Townsend

Genius 3141 points

Hi Tyler-san,

Thank you for your support.

I will check with the customer regarding the marking.

Does the confirmation of the marking imply that there is a possibility of a lot abnormality?

Best regards,

Kyohei

0 Tyler Townsend 8 months ago in reply to Kyohei

TI__Guru 65698 points

Hi Kyohei,

Not so much a lot abnormality, but checking for counterfeit devices.

Another angle is that the timing for the I2C bus is outside specifications. One TCA9554A may recognize the data stream, another device of its kind may not.

How is the customer generating the I2C write sequence? Is it bit-banging, or are they using a defined processor / MCU or some other I2C driver such as an AARDVARK.

Regards,

Tyler

0 Kyohei 7 months ago in reply to Tyler Townsend

Genius 3141 points

Hi Tyler-san,

Thank you for your support.

I have sent the lot numbers and X-ray images of the devices via private message.
As a difference between the working units and the non-working units, there appears to be a change in the assembly, including differences in the die pad and lead frame.
Could you please advise whether this assembly change could be related to the current issue?
We would appreciate your review.

Best regards,

Kyohei

0 Tyler Townsend 7 months ago in reply to Kyohei

TI__Guru 65698 points

Hi Kyohei,

I did not receive the information.

Can you resend at t-townsend@ti.com?

Maybe you sent to a different Tyler.

Regards,

Tyler

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TCA9554A: Regarding the issue where the TCA9554A does not return an ACK to the register address