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# INA290: Gain inquiries

Part Number: INA290

Hi Team,

Our customer is considering the INAx290 in his application and has the following inquiries.

My requirement is to measure low differential voltage (2-20mV) with 54V common mode voltage

Can you let me know the gain variants of the IC which is more suitable for me

I can see A1 - A5 variants are available. what does gain 20V/V to 500V/V really mean?

I wanted to know if we need any discrete component for this INA series? I can see we don't need any discrete components in data sheet, so its direct connection to current sense and other end to DAQ.

Also In table 8-1, page 20 of data sheet specifies the Vsense for A5 as 10mV, does it mean the min it can sense 10mV or much lower it can sense. Also wanted to the resolution (min step size) in mV (min it can measure and the step).

Regards,

Danilo

• Hi Danilo,

• To choose a proper gain variant, you would want to know the IC power supply and DAQ’s input range. If you can use 20V as power supply then any gain variant is OK; if 5V, then gain variants under 200V/V would be fine. Among all suitable gains, typically you want to choose the highest, while considering if there are transients that may cause output to clip.
• What does gain 20V/V to 500V/V really mean? – using 500 as an example, at 20mV input, we expect the output to be 20mV*500=10V, if the power supply is higher than 10V, therefore output is not limited.
• Any discrete component? - You don't need any discrete components at input or output. However when the characteristics of the input signal and output circuitry connected to the IC are not very clear, it is a good idea to put in place input filtering as shown section 8.1.2, as well as a low pass RC filter at the output (typically a couple of 100Ohm and >=0.05nF)
• Also In table 8-1, Vsense for A5 as 10mV – this is just an example, it doesn’t mean there is a limit to Vsense. The minimum Vsense it can measure is determined by the application’s error tolerance. Here is a plot showing the % error with respect to input differential voltage 2-20mV

Regards, Guang