DS90UB913A-Q1: i2c Vol problem

Hi Terry,

It looks like the snapshot attached is for I2C communication. If this is the case, it has been violated the specs. The maximum value is ~0.4V for V_OL.

Aaron

Hi Aaron,

Thanks your comment ! 

May I know any incorrect design will cause this problem as you know ?

TKS !

Hello Aaron,

Provide waveform as attach file.

If the i2c host in De-serializer side and send command to Serializer side 913A<= Will not see i2c waveform in Serializer side

If the i2c host in De-serializer side and send command to Serializer side EEPROM <= the SDA Vol is much low 250mV (meet D/S spec)

If the i2c host in Serializer side and send command to 913A <= the SDA Vol is much high 619mV (over D/S spec)

Does this result reasonable ?

Many thanks !i2c.pptx

Hi Terry,

How many slave devices attached to this bus?

Aaron

Dear Aaron.

Good day.

Please kindly reference on below. Thanks for help~

Dear Aaron.

Good day.

Update more information on below. Please kindly help it. Thanks

I2C master will check each slave address, read ack bit back.

Vol from SENSOR and EEPROM are 0.33V,0.25V less than Vil(1.8x0.3=0.54V) but 913A vol is 0.6V greater than Vil.

Please confirm 913A Vol is qualified by TI’s specification.

Sensor

EEPROM

913A

Hello.

Can someone help me solve this problem? Thanks~

Hi AJ,

Could you please confirm how many devices on the same bus?

Aaron

Hi AJ,

Is there any way you can disable the sensor and EEPROM? I would like to see if it is still occurred after isolating the sensor and EEPROM.

Aaron

Dear Aaron / Casey.

Good day.

We remove the other two devices on I2C bus. The 913 vol voltage is down to 0.48V.

We also changed the 2.2K resistor to 4.7K and 10K Still the same situation. Please kindly help to check this issue. Thanks~

Remove the other two devices on I2C

10K Pullhigh

Hi AJ,

Thank you so much for checking. Do you mind if you can share the schematic? If you don't want to share on public, please let me know. I can invite you to a private chat.

Aaron

Dear Aaron

Please kindly reference on below. Thanks

Dear Aaron.

Good day.

Do you have any update?  Thanks for kindly help~

Hi AJ,

Thank you for providing the schematic. Unfortunately, TI isn't guaranteed if customer violates the specs. We need to get this fix. Based on my experience, seeing data isn't pulling down to ground is because there is another device is pulling high while 913 is trying to pulling down. Are you sure that there is no other devices beside EEPROM and the sensor? Also, could you please remove the caps on C273 and C275?

Aaron

Hi AJ,

After carefully thought about your schematic again, I realized that I2C is connecting the caps to ground. I think this could be the issue since the I2C is switching at the rate of 400kHz or higher speed where you have the cap charge when it switch to high, and discharge when low. Please remove the caps and see if you the issue goes away.

Hope this helps. Let me know if this resolve the issue.

Aaron

Hi AJ,

Not sure if you have a chance to check my suggestion. I will close this for now; however, you can open it the case again anytime.

Aaron

Dear Aaron.

Good day. I will check your suggestion and update for you. Thanks for kindly help~

Dear Aaron.

Good day.

I am sure I have removed the EEPROM and Sensor I2C. After removing the C273 and C275, the waveform is as follows.

Please help confirm if there are other reasons. Thank you.