74HC7046AU Ver la hoja de datos (PDF) - NXP Semiconductors.
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74HC7046AU Datasheet PDF : 38 Pages
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Philips Semiconductors
Phase-locked-loop with lock detector
Product specification
74HC/HCT7046A
Fig.34 Frequency synthesizer.
Note
For an extensive description and application example please refer to application note ordering number
9398 649 90011.
Also available a computer design program for PLL’s ordering number 9398 961 10061.
1.6
∆ ωe (t) 1.4
∆ ωe /ω n
1.2
1.0
ζ= 5.0
0.8
ζ= 2.0
ζ= 0.3
0.5
0.707
1.0
MGA959
−0.6
−0.4 ∆ Φe (t)
∆ Φe /ω n
−0.2
0
0.2
0.6
0.4
0.4
0.6
0.2
0.8
0
1.0
0
1
2
3
4
5
6
7 ωnt 8
Fig.35 Type 1, second order frequency step response.
Since the output frequency is proportional to the VCO control voltage, the PLL frequency response can be observed with
an oscilloscope by monitoring pin 9 of the VCO. The average frequency response, as calculated by the Laplace method,
is found experimentally by smoothing this voltage at pin 9 with a simple RC filter, whose time constant is long compared
to the phase detector sampling rate but short compared to the PLL response time.
December 1990
37
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