[time-nuts] 10 MHz -> 16 MHz clock multiplier

Tom Van Baak tvb at LeapSecond.com
Tue Jan 8 03:54:31 UTC 2013


A week ago I asked about a 10 MHz to 16 MHz multiplier. Thanks very much for the suggestions and interesting discussion.

> What's the simplest way to generate 16 MHz from 10 MHz? This
> will be for clocking a microcontroller at 16 MHz given 10 MHz
> (Cs/Rb/GPSDO). Low price and low parts count is a goal; jitter
> is not a concern but absolute long-term phase coherence is a must.
> 
> The ICS525 (as in TAPR Clock-Block) is a good candidate but I
> was wondering if there's something cheaper, less functional, and
> maybe not SSOP. Any suggestions?
> 
> Thanks,
> /tvb

A few of you wanted to know more background. Some portable microcontroller-based timer/counters use a 16 MHz xtal timebase. To transparently give them "atomic" accuracy I thought it would be a cute hack to simply feed them 16 MHz as derived from a good 10 MHz (which we all have). For a quick test I used a house 10 MHz referenced DS345 to produce the 16 MHz square wave. I know some DDS have round-off error but the DS345, at least at this frequency, maintained phase to the nanosecond.

Not wanting to tie up my DS345 indefinitely, I wondered for this fixed 10:16 (5:8) frequency ratio if there was cheap, simple, or clever solution. The TAPR Clock-Block came to mind. The ICS525 chip it uses is cheap (under $5) and trivial to configure so that was clearly one solution. But I was curious what the group would propose.

Anyway, thanks to all who contributed. If there are any stones left unturned, send me email off-line.

/tvb
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