INA238: I2C communication failed / no ACK

Nothing special should be necessary. I can only suggest to check for shorts, missing power, and that the A0/A1 pins actually are grounded.

Please show an oscilloscope trace.

Your V_OL is very high, i.e., your pull-up resistors maybe are too strong. But this does not make these waveforms incorrect; they look OK otherwise.

Did you check the INA238's pins?

I agree with Clemens. What pull-up resistors are you using? 

The PullUps are 3K => 1mA which is full in I2C spec.
But the INA238 is not acc. spec: VILmax = 0.4V is stated in the datesheet while the I2C spec for fast mode mentioned 0.3*VDD = 1V in our 3.3V application. 

Does anyone knew, why this device isn't acc. spec or if there is a suitable replacement (pincompatible isn't necessary)

Thanks in advance
Thomas Sagcob

The I²C switching levels are designed to be 1.8 V compatible. Please try weaker pullups.

HI Clemens,
the operating range for I2C IOs is limited to 5.5V so it should work in this range acc. spec.
We've developed circuits for the Automobile industry since decades: we don't try any values; we design only against specification. Even if it's functional in any test it's unacceptable to be out of spec.

- INA226 input voltage limit is 36V which isn't suitable for us.

- An 1.8V I2C device should have a Vil_max of 30% * 1.8V = 0.54V and not only 0.4V. 

If a specification is mentioned in a datasheet it should be fulfilled under any conditions and usecase!! 

Hi Thomas, 

Our portfolio is I2C compatible, however it does not follow every specific detail of the I2C official specification. There was some small changes that needed to be done for the functionality of the part. I apologize for the inconvenience. Is there anything I could help you with? 

Best,

Mohamed