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Output Frequency of CN0349

Category: Hardware
Product Number: CN-0349


my question has been asked several times in different versions, but none of the answers given seem to help in my case. My problem is the output frequency of "vanilla" CN0349 Boards. It seems to me, that with the 1Mhz oscillator connected to MCLK of the AD5934, it is not possible to programm any values greater than approx. 7250 Hz into the Start Frequency Registers. My logic so far is that with the euqation given on page 13 of the AD5934 datasheet, the maximum value programmable to the AD5934 in Hz, which is still <= 24 Bit is about 7250. I came across this problem, because my measurements were consistantly wrong and all of them wrong in the same way. Now i've tested this theory and so far it seems to be true. As long as i program values below the 7250 Hz threshold, i can use the registers and get the desired output frequency. BUT for some unkown reason, which i cannot find an answer to, at about 30 kHz the Board just randomly changes direction and lowers the frequency instead of increasing it.

Now it would be just great if anybody could help me out. My 2 questions beeing:

1. Am i right with my assumption that with the given equation on page 13 of the AD5934 datasheet, it is not possible to programm values greater than ~7250 Hz, since this is the maximum value still equal to/under 24 bit?

2. Why is it not possible to increase the frequency above 30/31 kHz? Are there any ways to work around this problem?

If you have any questions i will gladly answer them.

Thanks in advance.