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AD9265 some bit is no ouput

Question asked by bg085 on Sep 2, 2012
Latest reply on Sep 5, 2012 by bg085

the hardware design is Strict reference the Evaluation Board User Guide(UG-003)of ANALOG DEVICE

 

(1)when AD9265 work in test mode ,all is ok.

(2)when AD9265  work in normal mode and dither disable,and the full range signal  sine wave is send to vin+ and vin-, bit8~bit11 (PIN18/PIN19/PIN21/PIN22) always hold a fixed level  .

(3)when AD9265  work in normal mode and dither enable, bit8~bit11 (PIN18/PIN19/PIN21/PIN22) always ouput only  random number,not  the correct adc output data.

 

 

ps:

Rbias pin  connect  to GND with a 10k Resistance.

Vref pin connect to GND with a 1.0 μF capacitor in parallel with a 0.1 μF capacitor  .

Sense pin  connect to GND directly.

Dither  pin  connect to GND with a 10k Resistance..

PDWN pin  connect to GND with a 10k Resistance.

 

The exposed thermal pad (pin 0)has been connect to AGND in PCB design.

This wrong is in cmos mode ,also in LVDS mode .

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