INA197: INA 197 non-linearity on range [0mV 2mV]

Marc GROMFELD

Part Number: INA197
Other Parts Discussed in Thread: INA293

I search support on INA197,

I use sense current AOP INA197 for a large range [0A ; 40A] with an sense resistor of 5mOhms .

The supply of amp is 12V and and force common mode (Vcm=+15V), in the aim to work in case describe in figure 26 to your datasheet component

"8.4.2.3 Low VSENSE Case 1: VSENSE < 20mV, −16v ≤ VCM < 0; and Low VSENSE Case 3: VSENSE < 20mV, VS < VCM ≤ 80V"

In my application ,i have curve simulary to the figure 26 some time (one time in two).

I have trace curve for current 0A to 400mA wich is equivalent to Vsense [0mV to 2mV]

See attachents document in x axis current 0 to 400mA and y axis V out of INA197 in mV

The curve is sometime linearity and other no linearity, i don't find an explication of this delta

One day i suppose offset Vos, but we i and this no better result.

It is possible to have some support on my application ?

Thank a lot

Best regard

over 2 years ago

0 kai klaas69 over 2 years ago

Guru 140200 points

Hi Marc,

yes, looks like input offset voltage error. Below I have simulated an input offset voltage running from -2mV and +2mV (in seven steps):

marc_ina197.TSC

Looks exactly like your curves.

Kai

0 Javier Contreras4 over 2 years ago

TI__Mastermind 27680 points

Hello Marc,

Kai is correct.

Can you use the INA293B2 or the INA281B2. The are a drop in replacement. They have better offset with the INA293 being the best. The major differences is the VCM cannot go below -4V which should not matter and bandwidth does change with Vsense voltage. They are normally faster but they do have some slower recovery if the inputs are saturated and slower at lower inputs. This information is all in the datasheet.