I am using a custom AD7367 ADC board . The schematic of the board is enclosed. I am using a precision 3.0 V external reference. Three such boards are fabricated. To my surprise ADCs on two of boards are generating BUSY as expected (after Convert_n goes low), but DoutA and DoutB both are always zero even after applying input voltage to VinA and VinB.
Second, One of the board is generating only DoutA and DoutB is again always zero.
Enclosed : 1. Schematic diagram. 2. captured signals using Scope
Signal Info: 0) Convert_n , 1) Cs_n, 2) Busy 3) DoutA, 4)DoutB, 5) SCLK
kindly suggest ! the probable the reasons for such behavior of the ADC to help me debug the issue.