Forums

12.288 MHZ synthesis

Started by Unknown October 14, 2004
Hi Group

I am designing a frequency synthesizer that produces a 12.288 MHz clock from
a 8 kHz input clock.

I was thinking about using a 74HC4046A VCO/PLL in combination with at
74HC4059 divider, but I'm not too happy about it. For one thing I only have
a 3V power supply, and the 4046A requires 3.0V to function. Another thing is
that at 3.0 V, the 12.288 MHz is rather close to the upper frequency limit.

Have any of you guys a better suggestion?

Best regards
Kresten


"Kresten N&#2013266168;rgaard" <knc@remooove_develco.dk> wrote in message
news:416e9146$0$209$edfadb0f@dread14.news.tele.dk...
> Hi Group > > I am designing a frequency synthesizer that produces a 12.288 MHz clock
from
> a 8 kHz input clock. > > I was thinking about using a 74HC4046A VCO/PLL in combination with at > 74HC4059 divider, but I'm not too happy about it. For one thing I only
have
> a 3V power supply, and the 4046A requires 3.0V to function. Another thing
is
> that at 3.0 V, the 12.288 MHz is rather close to the upper frequency
limit.
> > Have any of you guys a better suggestion? > > Best regards > Kresten >
Since you didn't include any of the requirements other than input and output center f, I'll throw out a suggestion: use a 12.288MHz VCXO that runs at 3V. Of course, you only get maybe +-100ppm pull range, but you didn't specify it so... good luck, Bob
Kresten N&#2013266168;rgaard schrieb in Nachricht
<416e9146$0$209$edfadb0f@dread14.news.tele.dk>...
>Hi Group > >I am designing a frequency synthesizer that produces a 12.288 MHz clock
from
>a 8 kHz input clock. > >I was thinking about using a 74HC4046A VCO/PLL in combination with at >74HC4059 divider, but I'm not too happy about it. For one thing I only have >a 3V power supply, and the 4046A requires 3.0V to function. Another thing
is
>that at 3.0 V, the 12.288 MHz is rather close to the upper frequency limit. > >Have any of you guys a better suggestion?
Why not use a pll clock synthesizer IC? For example Maxim and others build them. Ways simpler and smaller too! regards - Henry PS: I'm locking for a job as electronics designer. See my vitae in a few days on my homepage... -- <Schau auch mal auf meine Homepage www.ehydra.dyndns.info> <u.a. Versand von Wasserflohzuchtansatz, Wasserpflanzen/-schnecken, brasilianischer Sauerklee, Natron zum Backen/Baden, u.a.> <Alternativ &#2013266172;ber http://people.freenet.de/algenkocher>