Hi Team,
We are using the TMP112AQDRLRQ1 IC in our project, which operates at a maximum supply voltage of 3.6V. However, our controller operates at 5V.
We would like to know if the controller can reliably read the 3.3V I²C signals from the TMP112-Q1, or if we need to implement a level shifter to ensure proper communication and data accuracy.
We appreciate your guidance on this.
Thanks & Regards,
Kavivishnu
The TMP112A that you have specified has an Absolute Max Rating of 4V, so you must use a level shifter to connect it to 5V signals.
If you could switch to the TMP112D device, that one has an Absolute Max Rating of 6V that can tolerate 5V at it's I2C pins while powered with 3.3V at the V+.
When using the TMP112D with a 5V bus, you must ensure that the VOL signal from the controller meets the VIL requirement of TMP112. For a 3.3V supply, TMP112 would need the logic low to be less than 3.3*0.3 = 0.99V. A 5V bus with the same 30% ratio would have a limit of 5*0.3 = 1.5V, which would not meet the VIL Max requirement. In reality, most buses should pull close to 0V for logic low, so it should not be an issue. VIH is not a concern, because it is guaranteed to be exceeded by the higher voltage signal.
thanks,
ren
