🚀 go-pugleaf

In article <1993Jan6.132039.26487@cs.ucf.edu>, clarke@acme.ucf.edu (Thomas Clarke) writes:
> In article <1993Jan6.033742.14845@news2.cis.umn.edu> Mike Diack  
> <mike-d@staff.tc.umn.edu> writes:
> > In article <7116@m1.cs.man.ac.uk> Mark Robinson,
> > mark-r@spec0.ee.man.ac.uk writes:
> > >If anyone has a datasheet for the 74HC4046 PLL chip handy would
> > >you let me know how the frequency of the VCO is related to the
> > >values of R's and C and the max/min values that they can take.
> > >
> > >I want to run it with a lock range of about 1MHz, centred on
> > >8MHz, but the equations in the Maplin catalogue don't allow
> > >frequencies >2.8MHz (R=5k, C=50pF; ie the minimum allowed) even
> > >though they claim the VCO can get up to 15MHz. I think their
> > >data must be for the 4046 and none of our databooks are modern
> > >enough to include the 'HC4046 :-(
> > 
> > Something you should be aware of is that all HC4046's are NOT 
> > created equal. Two extremes I have found are
> > 1 : An SGS device that was barely able to oscillate at  1 MHz
> > (and the output waveform was triangular at that frequency)
> > and -
> > 2 : An RCA device that was still producing respectable square
> > waves at 10 Mhz
> > (Both devices running into a scope probe only , 5 volt supply)
> > 
> > At the frequency you want (8 Mhz) the design nomographs
> > become a bit irrelevant, as internal Cs & Rs dominate the issue.
> > 
> > I was driven to using LS124/324s, but i only wanted the vco
> > function, no doubt someone makes a better PLL.
> > cheers,
> Look at the Signetics NE564 - son of the old 560/1/2 .  It is a 
> PLL that gets up to about 30 MHz and has a TTL buffered output!
>

     You might want to take a look at the Motorola version of the 
54/74H4046. I have used the device in various circuits in a commercial
cellular application, and found them to be very stable.