AD7787

Question

Hi, 
 I am wanting to use the AD7787 for reading two single-ended signals, but one of the inputs is a differential input. I am guessing I can tie the - signal to ground and simply drive the + input with my single-ended voltage. i am hoping that by doing that I will have two inputs that are equivalent. I will be using a 4.096v reference and my input range will be 0-4.096v. Does anyone know if I am on the right track please? 
 Gerry

MaryMc · Accepted Answer

Hello Gerry, 
 AIN1+ is referenced to AIN1- while AIN2 is referenced to GND. With the buffer disabled, AIN1- can be tied to GND so AIN1+ and AIN2 are similar. 
 If the buffer is enabled, both AIN1+ and AIN1- are buffered. In this case, AIN1- requires 100 mV of headroom. So, AIN1-needs to be connected to some voltage that is 100 mV above ground. 
 AIN2 is also buffered when the buffer is enabled. However, the voltage seen by the ADC is still AIN2 - GND. 
 Regards, 
 Mary.

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AD7787