[time-nuts] Frequency Dividers

Tom Van Baak tvb at leapsecond.com
Tue Aug 8 16:50:59 EDT 2006


Hi Randy,

For most purposes seven 7490's or four HC390's or
three HCT40103, etc. will work just fine. Speaking
for myself, the main thing was parts count. And being
more of a software person than hardware I prefer a
one IC solution (which has the fun of software) to
a 3, 4, or 7 IC solution.

The other issues, which may or may not have any
bearing on some applications is that the latency
and the tempco of a multi-chip solution is likely
worse than a single IC solution.

Lastly, once one has programmed a PIC you realize
that dividing by almost any number is just as easy
as 10M so the same part and same PCB can be
used for all sorts of creative purposes.

/tvb

----- Original Message -----
From: "Randy Warner" <Randy at synergy-gps.com>
To: "Discussion of precise time and frequency measurement version=3.1.0"
<time-nuts at febo.com>
Sent: Tuesday, August 08, 2006 12:23
Subject: Re: [time-nuts] Frequency Dividers


> Guys,
>
> First off, what I am about to do is ask a REALLY STUPID question, but
> more and more of the GPS stuff I do is drifting towards the precision
> timing end of things, so I thought I should ask.
>
> I have been seeing a lot of traffic concerning making 10MHz frequency
> dividers using PIC's. While they provide an elegant solution to
> providing an accurate 1PPS from a precision source, I have to ask if
> there is a reason for going this route? I am just using three HCT40103
> down counters hooked to a DS4000 to get what I think is a very stable
> 1PPS. Am I missing something? I realize 40103's are as old as dirt (I
> guess I am showing my 4000 series CMOS days), but the HCT series have
> plenty of bandwidth.
>
> Please be gentle....
>
> Randy
>
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