Generating common mode voltage for AD779x

Hi,

There's a restriction on the analog input range and common mode voltage when the in-amp is active. This will really requires you an analog front end to ensure that the limits are not exceeded for correct operation and to avoid linearity performance. So if your input is around 10mV, the negative input should be bias to at least 1V to meet the common mode requirements.

Would you like to consider using the AD7124, it has all the building blocks of the AD7793 with some advanced features. In AD7124, the common mode range must be between (AVSS − 0.05 + 0.5/gain) and (AVDD − 0.1 − 0.5/gain). The part can also accept a pseudo differential input so it can operate in a single ended application as it has a flexible MUX in which any analog of the analog input pins can be positive or negative input. So, in your application you can connect your single ended input to the one of the positive input and you can use the bias voltage midway between the analog power supply rails generated internally as your negative input. This generated bias voltage can be made available at any VBIAS pins and you can connect this to your selected negative input.

Thanks,

Jellenie

Hi,

There's a restriction on the analog input range and common mode voltage when the in-amp is active. This will really requires you an analog front end to ensure that the limits are not exceeded for correct operation and to avoid linearity performance. So if your input is around 10mV, the negative input should be bias to at least 1V to meet the common mode requirements.

Would you like to consider using the AD7124, it has all the building blocks of the AD7793 with some advanced features. In AD7124, the common mode range must be between (AVSS − 0.05 + 0.5/gain) and (AVDD − 0.1 − 0.5/gain). The part can also accept a pseudo differential input so it can operate in a single ended application as it has a flexible MUX in which any analog of the analog input pins can be positive or negative input. So, in your application you can connect your single ended input to the one of the positive input and you can use the bias voltage midway between the analog power supply rails generated internally as your negative input. This generated bias voltage can be made available at any VBIAS pins and you can connect this to your selected negative input.

Thanks,

Jellenie