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INA238: increase VIL method or pin to pin alternative

Part Number: INA238
Other Parts Discussed in Thread: TCA9800, INA226, ISO1541

Hi sir,

I am looking for a pin to pin compatible device of INA238, with 0.3V VIL instead f 0.4V
Or ant method to make INA238 work with around 0.9V VIL.

Don't have to be 0.3V of Vdd, the device will be used with I2C isolator, as long as the VIL is above 0.8V in 3.3V, it will be fine.
Or is there any method to increase VIL of INA238?



  • It would be possible to insert a buffer like the TCA9800.

    But where does that 0.9 V value come from? Does this voltage actually happen, or is it a worst-case value for some large test current?

  • Like Clemens said, there are various buffers and level shifters you could use.  One other option would be to use the INA226.  It's older than the INA238, but is pin compatible and comparable in cost and accuracy (but has less features).  It's VIL is 0.3*Vs, so at 3.3V supply, that would be 0.99V.

  • Hi Mitch,

    Thanks for the recommendation.

    It seems INA226 is good. Sorry forgot to mention, another requirement is that it will be used for 48V system.

    If use INA238 in 5V supply, is it possible to increase the VIL? I am using 2 INA238, one is 3.3V and one is 5V, the 5V one work for me but 3.3V one does not (use same I2C isolator). Also if I increase the pull up resistor to 47k, the 3.3V one could acknowledge the address, but no luck on read and write. I would if there is any way to increase VIL, since the board is already made, I could not insert buffer.


  • Ah, ya, with 48V VCM, the INA226 will not work for you.  I did not realize that you were using an isolator.  You may want to look at our similar reference design: I have seen that when using an isolator, capacitors are often needed from SDA/SCL to GND on both sides of the isolation as used in the mentioned reference design. 

    VIL on the device cannot be changed, so you will need to get the voltage low enough to be registered. (Sometimes the isolator chips do not treat both sides the same, so if you are using a bidirectional chip, then reversing may also help. But that would require a hardware change.)

  • Hi Mitch,

    Thanks for the sharing.

    I am using AnalogDevices ADM3260 which is quite similar to ISO1541 in terms of side 1 and side 2 logic voltage level. In other words, if use INA238 with ISO1541, I suppose it will not work. So if in this case, is there any way to make it works without changing PCB layout?

  • Hello Frank,

    It looks to me like a PCB change will be needed....  Either you will need an isolator that has a VOL that is lower than 0.4V (does not seem common to me), or use a I2C buffer like Clemens said. (The TCA9800 recommended has a VOL max of 0.26V, so that will help. VIL is also 0.3*Vcc.  (I haven't double checked the logic high states for this device, as logic low was our main concern).