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# Understanding and calculating the AD9850 tuning word

I program the frequency of my device using a tuning word of 32 bits,

00000100   00011000   10010011   01110101     and I get an output frequency of 2 Mhz. I am unable to how this sequence of digits works.

From the datasheet

The relationship of the output frequency, reference clock, and tuning word of the AD9850 is determined by the formula

fOUT = (Phase × CLKIN)/2^32

where:

Phase is the value of the 32-bit tuning word.

CLKIN is the input reference clock frequency in MHz.

fOUT is the frequency of the output signal in MHz.

Maybe this is producing hex words rather than a number ?

Could someone perform a specimen calculation for say 500 Khz and then for 1500 Khz so I can see how it works  and how the string of digits is obtained ?

Also I would be grateful if someone may be able to point out the meaning of the power-down bit.

Parents
• I find maths is sometimes over complicated so I found the easiest way as follows:

(2^32 x Frequency Required) / clock speed(e.g. 125,000,000)

This gives you a Decimal number which you then convert to Binary and enter into the word.