When I used AD8575 as the buffer of the AD5791, the VREFP is +10V, and the VREFN is -10V, and I used the circuit the AD company had supplied. When the voltage output of AD5791 was between 10V to 5V, AD5791 was in a high degree of accuracy, but when the output was below the 5V, the degree of accuracy declined a lot. Then I checked my circuit, found that when the voltage output of the AD5791 was below the 5V, the reference voltage of the AD8676 pin 5 and pin 5 were the same, pin 7 was larger than pin 5. the reference voltage of the AD8676 pin 2 and pin 3 were sitll the same but pin 1 was larger than pin 2. I can't figure out this problem and expect somebody could help me. Thanks a lot!