Application Information
External Components
Component
R
1
R
2
R
3
C
1
C
2
C
3
C
4
C
5
Value
1.0MΩ
560kΩ
820kΩ
0.1µF
18pF
33pF
0.1µF
0.1µF
Tolerance
±10%
±10%
±10%
±20%
±20%
±20%
±20%
±20%
C
6
C
7
C
8
C
9
C
10
C
11
D
1
X
1
0.47µF
±20%
0.1µF
±20%
0.1µF
±20%
0.1µF
±20%
0.1µF
±20%
0.1µF
±20%
small signal type
4.0MHz
±0.01%
Note:
The values specified for R
1
, C
2
and C
3
have been found to be satisfactory when used with a crystal (X
1
) whose
equivalent series resistance is <= 1000 ohms. The crystal manufacturer should be consulted to determine optimum
values for different crystals.
The 0.1µF value for the dc blocking capacitors C
4
, C
5
, C
7
, C
8
, C
9
, C
10
and C11 are not a requirement. For the capacitors
C
4
, C
5
and C
10
, the input impedance is internal to the device and specified as typically 550kΩ. For the remaining
capacitors external circuits will be important in determining input impedance.
Fig.2 Recommended External Components
Input Pin Condition
Decode
Comp.
Input
Output Pin Condition
Rx Tone Rx Tone
Detect Decode
D
0
to D
5
Rx/Tx PTL
Result and/or Function
Tone
Tx Audio
Tx
Path
Enabled
Enabled
Tone
Decoder
Enabled
Rx Audio
Path
Enabled Notes
N
O
(
BIAS
)
N
O
(
BIAS
)
N
O
(
BIAS
)
Y
ES
Y
ES
Y
ES
1
2
3
4
5
6
T
ONE
0
0
X
0
1
Y
ES
Y
ES
N
O
N
OTONE
0
X
X
0
1
N
O
(
BIAS
)
Y
ES
N
O
T
ONE
1
0
0
0
1
N
O
(
BIAS
)
N
O
Y
ES
T
ONE
1
1
0
0
1
N
O
(
BIAS
)
N
O
Y
ES
T
ONE
1
X
1
1
0
N
O
(
BIAS
)
N
O
Y
ES
N
OTONE
1
X
X
X
0
N
O
(
BIAS
)
N
O
Y
ES
N
OTES
1
Normal tone transmit condition.
2
N
OTONE
programmed in Tx mode; tone transmit output set to V
DD
/2. Tx audio path enabled.
3
Normal decode standby.
4
Normal decode standby with PTL used to enable audio.
5
Normal ‘decode of correct CTCSS tone’ condition; PTL has no effect.
6
N
OTONE
programmed in Rx mode; tone transmit output (
BIAS
). Rx audio path enabled.
Table 1 Combinations of Input/Output Conditions
4
x = don't care
CMLMICRO [ CML MICROCIRCUITS ]
