Hi Greg, our ADS1120 (SPI), ADS112C04 (I2C) and ADS112U04 (UART) could measure single-ended signals using an external 5V VREF while providing gains of 1, 2 and 4. The devices can only support four single-ended measurements, but you could easily extend that using an additional MUX. Another option could be ADS1158 . This device supports 16 single-ended inputs, but will require one external gain stage. One general misconception that many customers have is that they think they always need to utilize the complete full-scale range of an ADC. But in the end it is only important that you can resolve the input signals to the level that is required by your application. Instead of using a gain of 32 in a 16-bit ADC, you could for example simply use the 24-bit options of the above mentioned devices ( ADS1220 , ADS122C04 , ADS122U04 , ADS1258 , ADS124S08 ) at a lower gain to get the same performance even though you only utilize a fraction of the full-scale range. If you get one more bit of resolution, this is nothing else than having an additional gain of 2. To give you an example: ADS1120 at 20SPS and Gain=4 yields an input referred noise of 15.6uVrms. If you could use Gain=32 in a single-ended configuration (not possible with ADS1120 ) you would achieve 1.95uVrms. ADS1220 at 20SPS and Gain=4 yields an input referred noise of 1.2uVrms. So you can see that ADS1220 at Gain=4 would yield better resolution than ADS1120 at Gain=32. ADS124S08 at 20SPS and Gain=1 yields an input referred noise of 0.8uVrms. Regards,
↧