Hi
I want to use INA231 in my project; considering this is the first time I have used this chip, I am not sure the circuit design is correct. Could you please check it and let me know if I missed anything or anything is incorrect?
VCC: 3.8V
VDD: 3.3V
VIN is connected to a power supply.
Thank you.
Best Regards,
Eric
Hey Eric,
Here is a link to an app note that can help you get started with digital current shunt monitors: https://www.ti.com/lit/pdf/sboa511. This document also has a link to an Excel tool that can help you pick the right shunt resistor for your design.
Other than the shunt, the circuit looks generally fine. I don't see the pullup resistors for the SCL and SDA, but I presume they are on a different section of the schematic.
One other note, is that I recommend using the error calculator tool on the product page to help verify your design. Even if I max out the shunt resistor for the tool with the INA231, your error is still fairly high:
The accuracy will improve as the shunt gets larger, but that will have more power drain. The excel tool should help you pick that.
Also, the input bias current for the INA231 is 10µA, which will make it very hard to measure such small currents. You would be better off switching to one of our newer devices that have a low IB, such as the INA238 (16 bit) or INA228 (20 bit). For example, if we put the same parameters into those error calculator tools, we can see the accuracy is significantly improved:
