Hi,
I am designing a controller as shown in the block diagram below. I am using low side current sensing with INA180. Max Current is 20A and sense resistor used is 0.002ohms.
Will there be any issue for sensing DC Input current if ground is on the IN+ terminal ?
As per datasheet, chip allows for a Vcm(common mode voltage) as low as -0.2V. Datasheet also mentions in the pin table, to connect IN- to ground. See the snippet below
Hi Cyril,
We expect it should work since the voltage seen at the -IN pin at the max current (20A * .002Ω = .04V below GND) is within the -0.2V recommended operating conditions spec.
However, the specification for CMRR isn't tested for voltages under 0V.
You also have to be careful that there are no transients that would push the voltage seen at the -IN pin below the absolute max of -0.3V.
Datasheet also mentions in the pin table, to connect IN- to ground. See the snippet below
This is a more typical low side current sensing configuration to which the data sheet refers to.
The second video titles "Design considerations for current sense amplifiers" in our series: Precision labs series: Current sense amplifiers | TI.com talks about high-side and low side considerations in more detail.
Best Regards,
Angel
