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AD7712 Output Data are always low


This is about receiving data register contents from AD7712.

First of all, I am using an Automatic Test Equipement to evaluate the AD7712. The ATE acts as a microcontroller to drive and read data from the ADC.  From the ATE we have also the supply voltages (AVdd and DVdd).

Master Clock is supply by an external fonction generator ( Square 10 MHz - CMOS Level )

The problem is that AD7712 cannot output Data. The outputs from the Data Reqister are always low.

I respect the latency  and the time for the output data rate

I follow the the Figure 13a on page 22 of the specification REV. F for the timing for reading operation from the data register

I would like my system to read data register continuously.

1. Power on

2 Activation of external MCLK

3. write control register (to enable 24-bit reading)

4. read control register (to check if control reg is written correctly)

5 Send differential voltage to AIN1

6 read data register with the ATE


+2.5V on ref in+

GND on ref in-

external clocking at 10.00MHz  CMOS Level (to MCLK IN)

UNIpolar input on AIN1 AIN2 unused

mode to gnd

standby to +5V

control register setting:

operating mode = normal, MD2=0, MD1=0, MD0=0

pga gain = 1, G2=0, G1=0, G0=0

channel selection = AIN1 low-level input, CH=0

power-down = normal,PD=0

word-length = 24-bit, WL=1

reserved = 1

burnout current = off, BO=0

bipolar/unipolar selection = bipolar, B/U = 1

filter selection, FS11-FS0, 12-bit, d1920

Thanks for your help