[time-nuts] Philips PLL

[Randy Warner]

 Said/Didier,

There just must be something special about Philip's PLL designs. Way
back when when I was working in the underwater world we used a small
underwater range finder (sonar) that used the Philips 4046 PLL. The
Philips part was the ONLY 4046 that would meet the range and jitter
specs. We used other parts if we needed to test something and weren't
too concerned about accuracy, but none of those sonars ever SHIPPED
without the Philips part inside.

Randy

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-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of SAIDJACK at aol.com
Sent: Tuesday, August 08, 2006 11:08 PM
To: time-nuts at febo.com
Subject: Re: [time-nuts] Frequency Dividers

In a message dated 8/8/2006 19:51:06 Pacific Daylight Time,
didier at cox.net
writes:
 
Hi Didier,
 
 
On the PLL: Philips typically does very well on their PLL's - jitter  is
very low. Certainly I've seen some of their PLL's in the ps range, which
would put the 1PPS output at probably better than 1E-11, 1s accuracy. I
can  measure the unit I have, and let you know later...
 
bye,
Said
 

I have  used a number of pll controlled microcontrollers, and I would
not recommend using one of those in a timing application such as those
discussed here.

These PLLs are generally not very clean spectrally  (it's actually a
good thing for EMI, some chips have purposeful spread  spectrum clocks)
and may have lots of jitter.

However, most of the  chips with PLL will let you disable the PLL and
run from a crystal or an  external oscillator. Alternately, it you use
the timer instead of software  loops, you can run the core from the PLL
as long as the timer itself is  not driven from the PLL.

I use the Silabs C8051F133  in several  projects and it will run with up
to a 100 MHz clock (with many  instructions running in one clock cycle)
from the PLL or I believe 50 MHz  with an external oscillator. And if
you needed a 16 x 16 MAC engine for  that counter, it has that too  :-)

http://www.silabs.com/public/documents/tpub_doc/dsheet/Microcontrollers/
Precis
ion_Mixed-Signal/en/C8051F12x-13x.pdf

That's  not your father's 8051!!!

For timing applications, it has 5 general  purpose 16 bit timers and a 6
channel 16 bit Programmable Counter Array,  so by using one of the 16
bit timer as a prescaler for the PCA, you can  have create up to 10
low-jitter timer outputs with 6 of them having up to  32 bits capacity,
with minimum software overhead, so the CPU is mostly  available for
anything else you might want to do with it..

Pretty  neat, uh?

The other day, a rep for a well known  semiconductor/microcontroller
company that shall remain nameless was  showing me their latest ad for
an
8051 running at 50 MHz with a 4 clock  core and in big letters: FASTEST
8051 AVAILABLE. I pointed him to the  Silabs web site and left him
there...

Didier KO4BB

PS: only  problem for the hobbyist, it only comes in a surface mount 64
or 100 pins  TQFP (cheap development boards are available, with JTAG
programmer,  prototyping area and serial interface). I am not associated
with Silabs,  however I am a very satisfied customer and I can recommend
their products  (hardware and software), they are topnotch and Silabs
customer service is  excellent. I routinely use them in products that
operate way outside the  generous -40 to +85 C temperature range without
any  problem.



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