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If used in cascade with the programmable divide–by–N
counter, practically all usual reference frequencies, or chan-
nel spacings of 25, 20, 12.5, 10, 6.25 kHz, etc. are easily
achievable.
PROGRAMMABLE DIVIDE–BY–N
4–BIT COUNTER (D2)
This counter is programmable by using inputs D P0 ... D P3
CF
f in
C
MC14569B
ZERO DETECT
LSD
Figure 6. Cascading MC14568B and MC14522B or MC14526B with MC14569B
PC in
PC out
(40 kHz)
C1
G
MC14568B
CTI
V SS
"0"
Q1/C2
PE
DP0 – – – – DP3
Frequencies shown in parenthesis are given as an example.
Figure 7. Frequency Synthesizer with MC14568B and MC14569B Using a Mixer
MC14568B
6–468
TYPICAL APPLICATIONS
CF
C
MC14522B
OR
MC14526B
PE
DP0 – – – – – – DP3
V SS
F
V SS
CF
Q
MC14569B
C
ZERO DETECT
(Channel Spacing 10 kHz)
(pins 7 ... 4). The Preset Enable input enables the parallel
preset inputs D P0 ... D P3 . The "0" output must be externally
connected to the PE input for single stage applications.
Since there is not a cascade feedback input, this counter,
when cascaded, must be used as the most significant digit.
Because of this, it can be cascaded with binary counters as
well as with BCD counters (MC14569B, MC14522B,
MC14526B).
CF
Q4
C
Q4
MC14522B
OR
MC14526B
"0"
PE
"0"
DP0 – – – – – – DP3
VCO
MC14011
2M
Q1/C2
MC14568B
PE
"0"
DP0 – – – – – – DP3
f out
MSD
f out
(144 – 146 MHz)
V DD
2 k
CRYSTAL
OSCILLATOR
(143.5 MHz)
MOTOROLA CMOS LOGIC DATA
MIXER
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