Si3220/Si3225
Ringtrip Timeout Counter
mode change (active mode). The ringtrip timeout
counter ensures ringing is exited within its time setting
(RTCOUNT x 1.25 ms/LSB, typically 200 ms).
The Dual ProSLIC incorporates a ringtrip timeout
counter, RTCOUNT, that will monitor the status of the
ringing control. When exiting ringing, the Dual ProSLIC Ringtrip Debounce Interval
will allow the ringtrip timeout counter a sufficient amount
of time (RTCOUNT x 1.25 ms/LSB) for the mode to
switch to On-hook Transmission or Active. The mode
that is being exited to is governed by whether the
command to exit ringing is a ringing active timer
expiration (on-hook transmission) or ringtrip/manual
The ac and dc ring trip debounce intervals can be
calculated based on the following equations:
RTACDB = t
RTDCDB = t
(1600/RTPER)
(1600/RTPER)
debounce
debounce
RTACTH
AC Ring Trip
Threshold
LFS
_
Debounce
Filter_AC
Input
Signal
RTP
Digital
LPF
Full Wave
Rectifier
ILOOP
+
Processor
Interrupt
RTACDB
RTRIPS
Logic
RTPER
Digital
LPF
RTRIPE
+
_
Debounce
Filter_DC
DC Ring Trip
Threshold
RTDCDB
RTDCTH
Figure 27. Ring Trip Detect Processing Circuitry
Rev. 1.0
51
SILICONIMAGE [ Silicon image ]
