CPC5710N Datasheet, PDF (5/9 Pages) Clare, Inc. – Phone Line Monitor (PLM) IC

2. Applications
CPC5710N
2.1 Another-Phone-Off-Hook (APOH) and Line Polarity Detector
This circuit performs two additional phone line
interface functions, APOH and line polarity detection.
The APOH output is logic low if another phone
connected in parallel to the detector is off-hook,
specifically, if the tip lead to ring lead voltage is less
than approximately 18 V.
The polarity output indicates the polarity of the phone
line. If tip is positive with respect to ring, polarity out
will be high.
Figure 3. APOH and Polarity Detection Application Circuit
U1 CPC5710
A
R1-4
8.06 MΩ
1% EIA
TIP 1206
R5
604 KΩ
RING
LIN/CMP
VDD
IN+
IN-
+
1.625 V
-
-
+
0V
AV=6
2V
VSS
+
1.25 V
-
Unless noted otherwise:
All resistors 1%, 1/16 W.
All capacitors 16 V 10%.
+V
VDD
VDD
CMPOUT
LINOUT+
LINOUT-
VSS
VSS
R14
4.7 MΩ
+V
R16
10 KΩ
R13
20 KΩ
1/4 U2
IN+ ^LM339
OUT
IN-
R12
20 KΩ
R11
499 KΩ
R10
21 KΩ
R8
A
20 KΩ
R9
499 KΩ
R17
4.7 MΩ
1/4 U2
IN+ ^LM339
OUT
IN-
R6
4.7 M
1/4 U2
IN+ ^LM339
OUT
IN-
R7
21 KΩ
Polarity
OUT
+V
R15
10 KΩ
APOH
OUT
C1
1 nF
A
A
A
Rev. 1.0 12/16/2002
www.clare.com
5