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CMX641A

Dual SPM Detector plus Payphone Security
Features:
  • Two (12.kHz/16kHz) SPM Detectors
  • Detects 12kHz and 16kHz SPM Frequencies
  • Xtal Controlled Accuracy
  • "Controlled" (µC) and "Fixed" Signal Sensitivity Modes
  • Selectable Tone-Follower or Packet-Mode Outputs
  • High Speechband Rejection Properties
  • 'Output Enable' Multiplexing Facility
Applications:
  • Call Charge Applications on PABX Line Cards
  • Complex and/or Simple Telephone Systems, Hotel and Office Call-Charge/Logging Sytems
  • Billing Systems
  • Public Call Monitoring
  • Payphone Systems
  • PCMCIA Fax and Data Modems
Packages:
  • CMX641AD2 - 24-pin SOIC
  • CMX641AP4 - 24-pin PDIP
Supply Requirement:
  • 2.7 to 5.5 V power supply
Description

The CMX641A is a low power, system selectable 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 sensitivity, frequency and bandwidth are independently selectable for each channel, under µC control, as is the frequency of the security tone generator, which may be ASK modulated by an external signal.
The CMX641A is also backwards compatible with the FX641 and MX641 dual SPM detectors, whilst offering a lower operating voltage and power requirement.

The CMX641A has two modes of operation:
  1. Fixed Bandwidth Operating state, in which the two channels are set to the same system frequency and sensitivity setting.
    Sensitivity and system frequency can be under either µC or external control. This state is fully pin and function compatible with the FX641 and MX641.

  2. Enhanced Features Operating state, under µC control, in which each channel has independently controllable sensitivity, bandwidth and system frequency (12kHz or 16kHz).
    There is also a 12kHz/16kHz transmission tone which can be keyed on and off directly by a dedicated logic pin.
This device is suitable for PBX/PABX line-card installations, payphone security applications and pair-gain systems.
The CMX641A is available in 24-pin plastic DIL and SOIC packages and consumes typically 1.2mA at 3V.
Block Diagram

CMX641A: a low power, system selectable Dual Subscriber Pulse Metering (SPM) Detector; two detectors on a single chip

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