CMX138 CML Microcircuits, CMX138 Datasheet - Page 67

• Manufacturer Part Number: CMX138
• Description: Audio Scrambler and Sub-Audio Signalling Processor
• Manufacturer: CML Microcircuits

Audio Scrambler and Sub-Audio Signalling Processor
11.1.4 Parametric Performance
For the following conditions unless otherwise specified:
© 2008 CML Microsystems Plc
Notes:
AC Parameters (cont.)
CTCSS Detector
In-band Tone Detector
DCS Decoder
Sensitivity
Response Time
De-response Time
Dropout immunity
Frequency Range
Sensitivity
Response Time
De-response Time
Drop-out immunity
Frequency Range
Sensitivity
Bit-Rate Sync Time
External components as recommended in Figure 2.
Maximum load on digital outputs = 30pF.
Xtal Frequency = 6.144MHz ±0.01% (100ppm); Tamb = −40°C to +85°C.
AV
Reference Signal Level = 308mVrms at 1kHz with AV
Signal levels track with supply voltage, so scale accordingly.
Input stage gain = 0dB, Output stage attenuation = 0dB.
71
72
73
75
DD
= DV
DD
Sub-Audio Detection Level threshold set to 16mV.
Composite signal = 308mVrms at 1kHz + 75mVrms Noise + 31mV rms Sub-Audio
signal. Noise bandwidth = 5kHz Band Limited Gaussian. For Sub-Audio signals
above 100Hz. Signals below 100Hz will take longer to detect.
In-band Tone Detection Level threshold set to 16mV.
With sub-audio dropout time (P2.5) set to = 120ms. The typical dropout immunity
is approximately 40ms more than the programmed dropout immunity. The typical
de-response time is approximately 90ms longer than the programmed dropout
immunity. See section 9.2.3 P2.5.
= 3.0V to 3.6V.
(Pure Tone)
(Composite Signal)
(Composite Signal)
(Pure Tone)
(Good Signal)
(Good Signal)
(In-band tone)
Page 67
Notes
72, 75
71
72
75
73
71
DD
Min.
288
60
58
–
–
–
–
–
–
–
–
–
= 3.3V.
Typ.
−26
140
210
160
−26
29
–
–
–
–
–
2
Max.
3000
250
260
50
20
–
–
–
–
–
–
–
D/138_FI1.0/5
mVp-p
edges
CMX138
Unit
ms
ms
ms
ms
ms
ms
dB
Hz
dB
Hz