CML Semiconductor Products

SPM and Security Subsystem

FX651

© 1997 Consumer Microcircuits Limited

D/651/4 September 1997

1.0

Features

Provisional Information

Functions:

Sensitivity

(SOIC) Package

Frequency Specifications

Installations

Applications

1.1

Brief Description

The FX651 integrated circuit combines 12kHz Subscriber Private Metering (SPM) detection with 18kHz

tone processing for anti-fraud purposes within a telephone system. This compact, low power device is

suitable for battery or line powered systems. Under simple logic or

µProcessor control it will:

Decode 12kHz SPM pulses in the presence of high level voice and 18kHz signalling, and

provide a logic output.

Transmit an NRZ modulated 18kHz security tone to line.

Decode an incoming modulated 18kHz security tone in the presence of high level voice

and 12 kHz SPM tones, and provide a logic output.

Employing high accuracy switched capacitor filters, the FX651 is protected from crosstalk and false

decoding.