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The CMX661 is a low power, Dual Subscriber Pulse Metering (SPM) Detector – two detectors on a single chip – to indicate the presence on a telephone line of either 12kHz or 16kHz telephone call charge frequencies.
The detection frequency and bandwidth are common to both detectors and may be externally selected.
The detection sensitivity is set independently for each channel by external components and the
detector outputs can be set to a high-impedance state for device multiplexing requirements in
PBX and PABX line card applications.
Flexibility of decode bandwidth settings allows the CMX661 to operate in systems where the SPM generation is not necessarily perfectly accurate or stable. External hardwired selection of functionality economises on the number of host µC I/O control lines required, whilst the rapid response and de-response times of the CMX661 permit flexible tone length qualification by the host µC.
