CMX602BD4 MX-COM, Inc., CMX602BD4 Datasheet - Page 10

• Manufacturer Part Number: CMX602BD4
• Description: Calling line identifier plus call waiting
• Manufacturer: MX-COM, Inc.

Calling Line Identifier plus Call Waiting (Type II)
4.8 Tone Alert Detector
The Tone Alert Detector block is enabled when the CMX602B is set to Tone Alert Detector operating mode. It
then monitors the received signal for the presence of simultaneous 2130Hz and 2750Hz tones of sufficient
level and duration.
Two digital bandpass filters, centered around 2130Hz and 2750Hz, are used within the block to provide
additional rejection of interfering signals.
The CMX602B DET output will be set high while Tone Alert signal is detected.
When DET goes low at the end of the Tone Alert signal, the
high for a period of time falling within the CAS qualifying time (t
remain low until the CMX602B is switched out of Tone Detect mode. This IRQ falling transition indicates a
valid CAS dual-tone has occurred.
Note: The t
off-hook applications. The longer (88ms to 110ms) Tone Alert signal employed by British Telecom for on-
hook applications will not necessarily cause IRQ to go low.
4.9 Ring or Line Polarity Reversal Detector
These circuits are used to detect the Line Polarity Reversal and Ringing signals associated with the Calling
Line Identification protocol. Figure 10 illustrates their use in a typical application.
4800 Bethania Station Road, Winston-Salem, NC 27105-1201, USA
2000 MX-COM, Inc
QCAS
IRQ for ZP
timing has been optimized for the detection of 75 to 85ms CPE Alert Signals (CAS) used in
Line Signal
MODE, ZP
Line
A
B
Bridge Rectifier output (X)
LO
DET
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IRQ
Protection
Network
or [ZP and MODE
See Section 6.1 for definitions of t
Line
Figure 10: Ring or Line Polarity Reversal Operation
HI
t
DTON
Figure 9: Tone Alert Detector Operation
DET for ZP
C3
C4
Ring Signal
R4
R3
LO
RT
HI
Tone Alert Detect mode
Tone Alert signal
]
R1
R2
D1-D4
RD
10
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From Tone Alert,
Energy Detector and
Data Retiming blocks
DTON
A
IR Q
C5
QCAS
output will be pulled low, only if DET was
, t
IRQ will only be pulled low if
DET output was high for t
DTOFF
) limits (See Section 6.1). IRQ will
RT
t
DTOFF
B
and t
CMX602B PRELIMINARY INFORMATION
R5
QCAS
Other mode
V
DD
Vt
Vt
V
V
QCAS
SS
SS
HI
HI
DET
IRQ
ZP
MODE
Doc. # 20480204.002