INA193 current sensor on isolated power line

Hello Yossi,

Thank you for your post. I would like a little bit more information on your application.

What is the application requirement driving the need for separate grounds? 

What are the expected voltages for Supply_IN and RTN_IN?

What is the expected current through the 20mΩ shunt resistor?

Best Regards,

Joe

Hi Joe,

I have a system with seperated ground. Supply_In and RTN_In driven 18-36V and I expect max current of 3.5-4A that would go through INA193.

after that it connect to Isolated DC/DC and the output ot the DC/DC make the main gorund.

Best Regards,

Yossi

Hello Yossi,

I need a full schematic to understand what grounds are connected where.

Please provide a schematic where all connections to the GND and RTN_IN nodes are highlighted. 

Thank you,

Joe

Hi Joe,

See Attach schematic.

Please see how this all connect, I worried about the isloation between this gnd beacuse INA193.

1212.design1.pdf

Best Regards,

Yossi

Thank you Yossi,

Is the output signal of the INA193 being fed to a microcontroller? 

Best Regards,

Joe

Hi Joe,

Yes.

My question is if the GND connection is right ?

I am worried that the current that need to measured is "float" beacause it have another GND.

Best Regards

Yossi

Hello Yossi,

I would like you to try to remove the C2 1uF output capacitor. This is a very large output capacitor and and this can cause oscillations.

For sense voltages greater than 20mV, the maximum capacitive load is 10nF. Your design is operating in the 70mV to 80mV range for Vsense. 

Please let me know if this experiment with removing C2 works for you.

Best Regards,

Joe

Hi Joe,

C2 is optional for me. I can remove it or put something else.

I want to get back to my main issue, the GND connection is good ? I would get isolation between the GND and RTN ?

Yossi