CMX641AP4 View Datasheet(PDF) - CML Microsystems Plc
Part Name
Description
MFG CO.
'CMX641AP4' PDF : 26 Pages View PDF
Dual SPM/Security Detector/Generator
CMX641A
In controlled sensitivity mode, the ‘will detect’ bandwidth is internally set at ±1.5% i.e. in 12kHz mode, the
CMX641A will detect frequencies between 11.82kHz to 12.18kHz inclusive. In 16kHz mode, it will detect
frequencies between 15.76kHz to 16.24kHz inclusive. The ‘will not detect’ bandedges are ±4% so that, in
12kHz mode, the CMX641A will not respond to frequencies of 11.52kHz or lower or to 12.48kHz or
higher. In 16kHz, the equivalent frequencies are 15.36kHz and 16.64kHz.
Fixed Sensitivity Mode (PRESET LEVEL pin = logic ‘1’ or open circuit)
In this mode, the sensitivity of each channel is set by correct selection of external components around
each Channel input amplifier. See section 1.6.5 and Figure 6 for a method of selecting amplifier gain
and components to meet a particular sensitivity requirement.
1.5.2.2 Enhanced Features Operating State (ENHANCED FEATURES pin = logic ‘1’)
This state is selected by tying pin 23 to logic 1. It has individually programmable tone detect
bandwidths, signal sensitivities and a 12kHz or 16kHz ASK keyed transmission tone. Control of the
CMX641A in this state is via a 16-bit serial data word, as shown in Table 3. Data is loaded bit 15 (D15)
first (See Figure 8).
Channel 2
D15-D11
D10-D9
Level
Sensitivity set
Bandwidth
as in Table 2
Control
Above
Channel 1
D8-D4
D3-D2
Level
Sensitivity set
Bandwidth
as in Table 2
Control
Above
System Select
D1-D0
12kHz or 16kHz
Select
Table 3 16-Bit Serial Input Word in Enhanced Features Operating State
Channel Level Sensitivities
These are independently programmable via bits D15-D11 for channel 2 and bits D8-D4 for channel 1.
The 5-bit coding and sensitivities are as given in Table 2 above for the Fixed Bandwidth Operating State.
For example, if D15-D11 = ‘01001’ and D8-D4 = ‘00101’, both in 12kHz mode, then channel 2 would have
a nominal sensitivity of –26.5dB(ref) and channel 1 would have a nominal sensitivity of –22.5dB(ref).
Will Detect and Will Not Detect Bandwidths
There are four individually programmable bandwidths per channel. The ‘will detect’ bandwidth can be
programmed to ±1.5%, ±3%, ±5% or ±7.5%. The corresponding ‘will not detect’ band edges are ±4%,
±5.5%, ±7.5% and ±10%. Bits D10 and D9 control channel 2 and bits D3 and D2 control channel 1.
D10-D9 (Channel 2)
D3-D2 (Channel 1)
00
01
10
11
Lower
Will Not Detect
11.52kHz (-4%)
11.34kHz (-5.5%)
11.10kHz (-7.5%)
10.80kHz (-10.0%)
Lower
Will Detect
11.82kHz (-1.5%)
11.64kHz (-3.0%)
11.40kHz (-5.0%)
11.10kHz (-7.5%)
Upper
Will Detect
12.18kHz (+1.5%)
12.36kHz (+3.0%)
12.60kHz (+5.0%)
12.90kHz (+7.5%)
Upper
Will Not Detect
12.48kHz (+4%)
12.66kHz (+5.5%)
12.90kHz (+7.5%)
13.20kHz (+10.0%)
Table 4 Setting 12kHz Will Detect/Will Not Detect Bandwidths in
Enhanced Features Operating State
© 2002 Consumer Microcircuits Limited
13
D/641A/5
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