Application Information
External Components
Component
Value
Tolerance
R1
R2
1.0MΩ
560kΩ
820kΩ
0.1µF
18pF
33pF
0.1µF
0.1µF
±10%
±10%
±10%
±20%
±20%
±20%
±20%
±20%
C6
C7
C8
C9
C10
C11
D1
X1
0.47µF
0.1µF
0.1µF
0.1µF
0.1µF
±20%
±20%
±20%
±20%
±20%
±20%
R
C31
C2
C3
C4
C5
0.1µF
small signal type
4.0MHz
±0.01%
Note: 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 ohms. The crystal manufacturer should be consulted to determine optimum
values for different crystals.
The 0.1µF value for the dc blocking capacitors C4, C5, C7, C8, C9, C10 and C11 are not a requirement. For the capacitors
C4, C5 and C10, 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
Output Pin Condition Result and/or Function
Decode
Comp.
Input
Tone
Tx
Enabled
Tx Audio
Path
Enabled
Tone
Decoder
Enabled Enabled Notes
Rx Audio
Path
Rx Tone Rx Tone
Detect Decode
D0 to D5
Rx/Tx PTL
TONE
NOTONE
TONE
TONE
TONE
0
0
1
1
1
1
0
X
0
1
X
X
X
X
0
0
0
0
1
X
1
1
1
1
0
0
YES
YES
YES
NO
NO
NO
NO
NO
NO
YES
YES
YES
YES
NO (BIAS)
NO (BIAS)
NO (BIAS)
YES
1
2
3
4
5
6
NO (BIAS)
NO (BIAS)
NO (BIAS)
NO (BIAS)
NO (BIAS)
0
0
1
X
YES
YES
NOTONE
NOTES
1
2
3
4
5
6
Normal tone transmit condition.
NOTONE programmed in Tx mode; tone transmit output set to VDD/2. Tx audio path enabled.
Normal decode standby.
Normal decode standby with PTL used to enable audio.
Normal ‘decode of correct CTCSS tone’ condition; PTL has no effect.
NOTONE programmed in Rx mode; tone transmit output (BIAS). Rx audio path enabled.
Table 1 Combinations of Input/Output Conditions
x = don't care
4
CMLMICRO [ CML MICROCIRCUITS ]
