Low Voltage CTCSS Encoder/Decoder
6
MX465
3
External Components
Figure 2 : Recommended External Components for Typical Application
R1
R2
R3
C1
C2
C3
C4
C5
Note 1
Note 1
Note 2
Note 2
Note 1
1.0M
Ω
560k
Ω
820k
Ω
0.1
µ
F
18pF
33pF
0.1
µ
F
0.1
µ
F
±
10%
±
10%
±
10%
±
20%
±
20%
±
20%
±
20%
±
20%
C6
C7
C8
C9
C10
C11
D1
X1
Note 1
Note 2
Note 2
Note 2
Note 2
Note 2
0.47
µ
F
0.1
µ
F
0.1
µ
F
0.1
µ
F
0.1
µ
F
0.1
µ
F
small signal
4MHz
100ppm max.
±
20%
±
20%
±
20%
±
20%
±
20%
±
20%
Table 2: External Components
External Components Notes:
1. The values specified for R1, C2, and C3 have been found to be satisfactory when used with a crystal
(X1) whose equivalent series resistance is
≤
1000
Ω
. For best results, a crystal oscillator design
should drive the clock inverter input with signal levels of at least 40% of V
DD
, peak to peak. Tuning
fork crystals generally cannot meet this requirement. To obtain crystal oscillator design assistance,
consult your crystal manufacturer.
2. The 0.1
µ
F value for the DC Blocking capacitors, C4, C5, C7, C8, C9, C10, and C11 is not a
requirement. For the capacitors C4, C5, and C10, the input impedance is internal to the device and
specified typical as 550k
Ω
. For the remaining capacitors external circuits will be important in
determining the input impedance.
©1998 MX•COM, INC.
www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054
Doc. #20480143.010
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