ISO1540: Designing with ISO1540DR

Hi Sv,

There was an issue with this E2E post and it was not allowing to respond. Therefore, I had delete the responses which is now allowing me to respond.

Sv said:

Does this mean the Vol at side 1 will not got to 0V.

Yes, that is correct. The VOL at Side1 can go up to 0.8V.
The below FAQ explains the reason behind this in more detail : https://e2e.ti.com/support/isolation-group/isolation/f/isolation-forum/757564/faq-why-is-the-logic-low-level-output-voltage-vol1-up-to-0-8v-on-side1-of-the-iso1540-iso1541-and-iso1640-iso1641-bidirectional-i2c-isolators

Sv said:

Will this create any logic comparability issues?.

Yes, this will cause logic compatibility issue.
You can try swapping Side1 to master side and Side2 to slave side to resolve this issue. Make Sure VIL of MSP432E401YTPDTR is more than 0.8V.

Sv said:

Also, in our case, the VCC1 is +5V and VCC2 is +3.3V.

This is not a problem, VCC1 and VCC2 voltages can be different as these supplies power two independent dice.

You also mentioned that the MCU VOL is 0.7V but do you know if its VIL > 0.8V? Regarding your question on whether increasing pull-up resistor will resolve the issue, no, the increasing / decreasing pull-up resistor doesn't change VOL and VIL levels.

If the MCU and INA devices are not compatible, then you can consider using I2C buffers like TCA9517A. Thanks.

Regards,
Koteshwar Rao