INA180: Gain of INA180A2 can't reach 50V/V

Ethan Tao

Part Number: INA180

Tool/software:

Hello,

I found the gain can't reach 50. the gain is about 24 when I used 1m ohm shunt resistor. but it change to 41 when I used 2m ohm shunt resistor.

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 318050 points

What current? Please note that the INA180 has an input offset of up to 150 µV.

0 Mallika Senthil over 1 year ago

TI__Expert 7860 points

Hi Ethan,

I would need to know the current being applied across the shunt to give you a more detailed answer. I would suggest applying two different current values across the shunt - ensure that the output with one of the current input is at least 150mV ( above clipping). Then take the difference of the two outputs to find your gain.

Please keep in mind the input offset as Clemens suggested and note that the INA180 is single ended. Also here are the conditions for device normal functionality as listed in section 8.4.1 of the datasheet.
https://www.ti.com/lit/ds/symlink/ina180.pdf?ts=1719501931384&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FINA180

Best,
Mallika Senthil

0 Ethan Tao over 1 year ago in reply to Clemens Ladisch

Prodigy 10 points

Thanks Clemens,

I did test with different load. the current is 5.08A and 22.9A. the shunt resistance is 2m ohm.

0 Ethan Tao over 1 year ago in reply to Mallika Senthil

Prodigy 10 points

Hi Mallika,

thanks for your support.

I did test again. here is current and sense voltage curve. channel 1: current probe. channel 4: INA180A2 out put.The calculation of gain is 41.3 and 41.2.

I think that it's effect of input offset. but I don't know how to fixed it.

0 Mallika Senthil over 1 year ago in reply to Ethan Tao

TI__Expert 7860 points

Hi Ethan,

Have you tried this setup with different INA180s? Please share your circuit schematic as well.

Best,
Mallika Senthil

0 Ethan Tao over 1 year ago in reply to Mallika Senthil

Prodigy 10 points

Hello Mallika,

Here is schematic. another graphic is layout. the routed length is 53.6mm. I have a try with INA180A1. the gain is about 16.4V/V.

0 Mallika Senthil over 1 year ago in reply to Ethan Tao

TI__Expert 7860 points

Hi Ethan,

I have a few follow up questions and suggestions.
Firstly, please point out where R9 and R10 are in the layout.
Second, where are you probing current and voltage from in your schematic.
Also, please check whether your voltage is going below (GND-0.3V) at the input pins. As a test, I would recommend checking gain after removing all RC filters on the output and passing a DC current.

Best,
Mallika Senthil

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INA180: Gain of INA180A2 can't reach 50V/V