CMX602B 查看數據表（PDF） - MX-COM Inc
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CMX602B Datasheet PDF : 22 Pages
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Calling Line Identifier plus Call Waiting (Type II)
10
CMX602B PRELIMINARY INFORMATION
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 IR Q output will be pulled low, only if DET was
high for a period of time falling within the CAS qualifying time (tQCAS) limits (See Section 6.1). IRQ will
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 tQCAS timing has been optimized for the detection of 75 to 85ms CPE Alert Signals (CAS) used in
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.
Line Signal
DET
tDTON
Tone Alert signal
IRQ
tDTOFF
IRQ will only be pulled low if
DET output was high for tQCAS
MODE, ZP
Tone Alert Detect mode
Other mode
See Section 6.1 for definitions of tDTON, tDTOFF and tQCAS
Figure 9: Tone Alert Detector Operation
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.
A
Line
B
Line
Protection
Network
C3 R3
C4 R4
D1-D4
From Tone Alert,
Energy Detector and
Data Retiming blocks
DET
IRQ
R1
RD
R2
A
C5
B
RT
R5
ZP
MODE
VDD
Ring Signal
VtHI
Bridge Rectifier output (X)
VSS
RT
VtHI
VSS
IRQ for ZPLO or [ZPHI and MODELO]
DET for ZPHI
Figure 10: Ring or Line Polarity Reversal Operation
2000 MX-COM, Inc
www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054
Doc. # 20480204.002
4800 Bethania Station Road, Winston-Salem, NC 27105-1201, USA All trademarks and service marks are held by their respective companies.
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