I'm having an issue with the ads7961. I have it configured as a single ended device. However, when I apply a voltage less than the 2.5V reference I get values between 000h and 7FFh. The datasheet indicates these values should be between 800h and FFFh. When I apply a voltage above 2.5V it also returns the CORRECT value between 000h and 7FFh. Can anyone give me any insight as to what I could be doing wrong?