How to calculate the HF LPO frequenzy with the HF trim

David Boehlen

Hi,

I know how to set the HF TRIM, but I want to understand how to calculate the HF LPO.

I found for the HF TRIM in the manual: the ration = f/fo

0h = 29.52

1h = 34.24%

2h = 38.85%

...

The HF LPO has a nominal frequency of 9.6MHz and a range from 5.5MHz to 19.5MHz.

What is now f and fo ?

fo = 19,5 Mhz and f = 9,6MHz --> trim = 9,6/19,5 = 49,23 % ??

Thanks for Help

+1 jagadish gundavarapu over 1 year ago

Hi David,

Please have a look on above thread once.

Here f means input frequency and fo is the output frequency.

So, the trim formula would be as below.

HFTRIM(%) = (Input Frequency(f) / Output Frequency(fo)) * 100

And now the output frequency will become as below from the forumla

Output Frequency (fo) = (Input Frequency(f) / HFTRIM(%)) * 100

So, based on applied HFTRIM value the output frequency will be produced from trimmed input frequency. That means

If HFTRIM is 0h then fo will be 0.2952*f

If HFTRIM is 1h then fo will be 0.3424*f

....

If HFTRIM is 10h then fo will be 1*f (That means output frequency is same as input frequency)

....

If HFTRIM is 1Eh then fo will be 1.555*f

If HFTRIM is 1Fh then fo will be 1.5935*f

And here nominal value of HFLPO is 9.6Mhz.

--
Thanks & regards,
Jagadish.

0 David Boehlen over 1 year ago in reply to jagadish gundavarapu

Thank you very much!