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AD8223 gain issue

Question asked by Pascal65535 on Sep 20, 2017
Latest reply on Oct 25, 2017 by harrynsc

Hello every one!

In my design, I am using a AD8223 as a current sense amplifier on a +5V 10A power supply.

Here is the AD8223 wiring:

-Vs = GND (0V)

+Vs = +15V

REF = GND

RG = 1.23kohm

IN+ and IN- are connected to the sense resistor, which is in series with the +5V output rail.

The sense resistor is 0.005ohm.

The power supply I am sensing runs in constant-current mode and can be set form 0A to 10A. Its output voltage can vary from 0V to 5V depending on settings and load.

 

If I correctly understand the datasheet, this configuration is possible. However, the voltage gain of the AD8223 is not 70 as expected but 80 according to my measurements.

I checked the resistors values and the power supplies and everything seems OK.

 

Do you know where the problem comes from?

 

Thank you!

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