Brief Description
The FX641 is a low-power, system-selectable Dual Subscriber Private 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.
Under µProcessor control via a common serial interface, each channel of the FX641 will detect call-charge pulses from a telephone line and provide a digital output for recording, billing or security purposes.

FEATUREs
● Two (12kHz/16kHz) SPM Detectors on a Single Chip
● Detects 12kHz and 16kHz SPM Frequencies
● Xtal Accuracy; Stable Frequency Limits
● “Controlled” (µC) and “Fixed” Signal Sensitivity Modes
● Selectable Tone Follower or Packet Mode Outputs
● High Speech-Band Rejection Properties
● “Output Enable” Multiplexing Facility
● Call-Charge Applications on PABX Line Cards