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AD9629 cannot output correct digital code at standalone mode

Question asked by wangis on Jul 25, 2016
Latest reply on Jul 25, 2016 by DougI

Hi

I have bought the evaluation board of AD9629-20 and I want to measure it under standalone mode.

I have set the Jumper as shown below:

J203: Pin 1 to Pin 2 (MODE_OR to LED)

J302: Pin 8 No Jumper  (Standalone mode)

          Pin 2 No Jumper (Default Mode)

          Pin 5 No Jumper (Offset Binary)

J605: Pin 1 to pin 2 ( internal oscillator)

J201 : Pin 2 to Pin 3 (internal 1V reference)

J202: No jumper.

The analog input signal is set as the 1MHz sine wave with 1Vpp and 0.5Voffset

Questions:

(1) Setup both inputs to VCM, default output code should be 1000-0000-0000, but output reveals 1111-1111-1x11

bit 3 of LSB keeps toggling ? Does any hardware configuration I miss so that ADC outputs wrong code ?

(2) If single end sine wave is given from SMA , output code reveals wrong waveform, it appears like a sine wave but MSB code is inverted.

 

thanks,

YH

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