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Question asked by anapoly on Apr 1, 2013
Latest reply on Apr 4, 2013 by anapoly

In the pin function description for AD9951 IOUT, it is described  "should be biased through a resistor to AVDD"

So whar is the resistor value?

  It seems there is no evaluation module for AD9951. I checked AD9954 EVM and found 25ohms for

the resistor.


1.   Could anyone give me any advice this is the proper value?  And why we need bias for IOUT? 

(I understand we need DAC_Rset for the DAC current but there is no clear description for the IOUT resistor.)


2. There are R4,R6 and R5,R7(all 0 ohm) for AD9954 COMP_IN.   I do not need those for AD9951, because thre is no COMP_In in the AD9951,

am I correct?

(By the way, why we need AVDD in the transformer midpoint (port 2)??   we should not connect the AVDD directly to the IOUT??)


Best Regards