AD7667 input question

Hi lzhang791,

If I understand you correctly, you want understand as this circuit convert +/-10 V input range to 0-2.5 V output. You can derive the transfer function of this circuit:

General view: Vout=Vin*k+b, where k is input signal gain, b is constant.

In this case:

If you don't understand how to do it, I can help you.

As result, output range

I hope this help you.

Regards,

Kirill

thank you，i understand。

i have another question:

   why use the multiplexer (U2)?  I thought the R3 connect the input.So the voltage I calculated is wrong.

Hi,

In fact, to input connect the reference voltage, not R3. U2 provide calibration or autozero mode. In datasheet says about this: "When desired, accurate gain and offset can be calibrated by acquiring a ground and voltage reference using an analog multiplexer (U2), as shown in Figure 45".

Regards,

Kirill

Hi,

In fact, to input connect the reference voltage, not R3. U2 provide calibration or autozero mode. In datasheet says about this: "When desired, accurate gain and offset can be calibrated by acquiring a ground and voltage reference using an analog multiplexer (U2), as shown in Figure 45".

Regards,

Kirill