🚀 go-pugleaf

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!
--
Thomas Clarke
Institute for Simulation and Training, University of Central FL
12424 Research Parkway, Suite 300, Orlando, FL 32826
(407)658-5030, FAX: (407)658-5059, clarke@acme.ucf.edu