Use AD8295 for Loadcell Amplifier Board

Hello, I'm making a loadcell amplifier board. Input from -18mVDC to +18mVDC. Output +-2.5V. Input signal frequency from 0 to 14Hz. I have made a design as the attach. The total gain changes from about 140 to 50 according to real condition.

- First, I don't know why the output is very fluctuated and gaining is wrong.

- Second, I intend changing the low-pass filter to pre-amp + filter. The IA will became to post-amp.

Anyone help me what is the wrong in my design and how to solve it.

Thanks,

Anhcao

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  • Thank you Scott,

    I intend use +-5V (total diff 10V) for loadcell. So the maximum common-mode voltage is about +-18mV. The voltage regulator is 7805 and 7905. What is the voltage at the Rg if input voltage is very low (mV) ? I haven't found any information about this in AD8295 at datasheet.

    I'm considering the AD8231. Can I use AD8231 as an pre-amp for the board? If the supply voltage is +-2.5V, the input voltage range is about +-2.2V ? I'm not sure this because I can't find the spec for dual-supply mode.

    Regards,

    Ahn

Reply
  • Thank you Scott,

    I intend use +-5V (total diff 10V) for loadcell. So the maximum common-mode voltage is about +-18mV. The voltage regulator is 7805 and 7905. What is the voltage at the Rg if input voltage is very low (mV) ? I haven't found any information about this in AD8295 at datasheet.

    I'm considering the AD8231. Can I use AD8231 as an pre-amp for the board? If the supply voltage is +-2.5V, the input voltage range is about +-2.2V ? I'm not sure this because I can't find the spec for dual-supply mode.

    Regards,

    Ahn

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