CMX641A データシートの表示（PDF） - MX-COM Inc

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CMX641A

Dual SPM/Security Detector/Generator

MX-COM Inc  

Dual SPM/Security Detector/Generator

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CMX641A Advance Information

Table 3 shows the serial data input to produce the required sensitivity. Minimum, nominal and maximum

sensitivity figures are provided to make complete allowance for internal circuit offsets and component

tolerances. The gain of each bandpass filter, and therefore the device sensitivity, is adjusted by the applied

serial bits D1 to D5. The system frequency is selected by bit D0 (‘1’ = 12kHz; ‘0’ = 16kHz). Data is loaded bit 5

(D5) first (See Figure 7).

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.

4.2.1.1.2 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 5.5 and Figure 6 for a method of selecting amplifier gain and

components to meet a particular sensitivity requirement.

4.2.2 Enhanced Features Operating State (ENHANCED FEATURES pin = logic ‘1’)

In this state, the following features of the two SPM detector channels are independently controllable via a 16-

bit serial data word from a host µController.

i. The decode bandwidths, which can be set to ±1.5%, ±3%, ±5% and ±7.5% of the nominal tone

frequency.

ii. The level sensitivity.

iii. The system frequencies, which have one of three possible settings: 12kHz & 12kHz, 16kHz & 16kHz, or

12kHz for Channel 2 and 16kHz for Channel 1.

When the two channels are set to 12kHz/16kHz mode, there is an option to disconnect the channel 2 decode

path from its own amplifier and have both channels connected to the channel 1 input. The channel 2 amplifier

is then independent and available for some other use, say gain setting or filtering, within the host circuitry.

There is also a transmit tone, selectable to 12kHz or 16kHz, which is ASK modulated via a logic input pin.

4.2.2.1 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 4. Data is loaded bit 15 (D15) first (See Figure 8).

Channel 2

D15-D11

D10-D9

Channel 1

D8-D4

D3-D2

System Select

D1-D0

Level Sensitivity

set as in Table 3

above

Bandwidth

Control

Level Sensitivity

set as in Table 3

above

Bandwidth

Control

12kHz or

16kHz

Select

Table 4: 16-Bit Serial Input Word in Enhanced Features Operating State

4.2.2.1.1 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 3 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).

ã2001 MX-COM, Inc.

www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054

Doc. # 20480227.002

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

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