Calling Line Identifier

FX602

© 1998 Consumer Microcircuits Limited

20

D/602/7

Notes:

1

When the FX602 is in Tone Alert Detect mode, the IRQN output will go low on the first high to low

transition of the DET output and will remain low until the FX602 is switched to FSK or Zero Power

mode. Accordingly the IRQN output should be ignored when looking for a CAS signal.

2.

The task of monitoring the FX602's DET output during the CONFIRM_QUIET state may be eased by

noting that in FSK Receive mode any high pulses on the DET output will last for at least 8ms (or until

the mode is changed) so the signal need only be monitored more frequently than once every 8ms.

3.

The actual duration of the '50ms' monitoring period is not critical but should be at least 30ms to allow

time for the FSK level detector to respond.