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AD9858 schematic

Question asked by Suluku on Jul 25, 2014
Latest reply on Sep 8, 2014 by Suluku

Hi all,

Im trying to use the AD9858 to generate a sweep frequency. For now I can generate the single tone as wanted and the sweep frequency to certain point, still need to work on this. All above is working when using the evaluation board Rev.(D) powered vcc, dvdd and avdd pins on 3.3v. No power to the 5v (CP) as not needed.

Im using serial programming.

My issue is with the schematic ( which is attached). I used the evaluation board schematic and ignored all the pins Im not using except the two 5v.

SP_Select(91), PS0(97) and PS1(98) are to GND.

How ever, when I use the circuit (assuming there are no shorts as I had soldered the chip to an TQFP100 adapter) I get no output on the RFOUT.

Questions:

- Is the circuit wrong?

- Is flotting pins causing this?

- For the RFOUT I used the WBC1-1TLB with the brown dot instead of the WBC1-1TL red dot on the board. Any issue?

- For the serial communication, if I understand, I need to use the AHC125, AHCT14 and the AHC574.

 

Thanks

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