[time-nuts] 74HC4046 receiver

Pete peterawson at earthlink.net
Thu Apr 9 01:09:24 UTC 2009


Quite correct, fumble fingers win again. As they say "here's
the rest of the story".

I was able to measure just 1 part. It is a NSC MM74HC4046N,
date code 9018, presumably still available from Fairchild. The VCO
was disabled (INH=H), the COMP input was grounded & I looked
at the PC1 output. Transition times were <3ns & abberations were
<5%. The resulting jitter measures:

Input Vp-p        Jitter ps rms
2.36                  8.6
2                       8.8
1.5                    9.2
1                       9.5
0.7                    10.2
0.5                    11.1
0.3                    14.5

I tried comparing this with a 74AC04, but my setup must be too
noisy as the best the 'AC04 could do was 12ps rms. The input to
the 'AC04 was AC coupled & yielded 49/51% duty cycle, apparently
switching cleanly with the 2.36Vp-p input. Ground bounch & ringing 
were <10%.

Pete Rawson

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