14
TELEPHONE LINE
ISOLATION BARRIER
RECEIVE
2-WIRE
ISDN
LINE
PROTECTION
CIRCUIT
TRANSMIT
LINE POLARITY
LINE PRESENCE
HCPL-4731
HCPL-4701
TELEPHONE
LINE
INTERFACE
CIRCUIT
PRIMARY–SECONDARY
POWER ISOLATION
BARRIER
SECONDARY/
EMERGENCY
POWER
EMERGENCY
POWER
SWITCHED–
MODE
V
V
CC
SECONDARY
POWER
VAC
PRIMARY
P0WER
SUPPLY
– RETURN
CC
POWER
SUPPLY
NOTE: THE CIRCUITS SHOWN IN THIS FIGURE REPRESENT POSSIBLE, FUNCTIONAL APPLICATION OF THE HCPL-47XX
OPTOCOUPLER TO AN ISDN LINE INTERFACE. THIS CIRCUIT ARRANGEMENT DOES NOT GUARANTEE COMPLIANCE,
CONFORMITY, OR ACCEPTANCE TO AN ISDN, OR OTHER TELECOMMUNICATION STANDARD, OR TO FCC OR TO OTHER
GOVERNMENTAL REGULATORY AGENCY REQUIREMENTS. THESE CIRCUITS ARE RECOMMENDATIONS THAT MAY MEET
THE NEEDS OF THESE APPLICATIONS. Agilent DOES NOT IMPLY, REPRESENT, NOR GUARANTEE THAT
THESE CIRCUIT ARRANGEMENTS ARE FREE FROM PATENT INFRINGEMENT.
Figure 10. HCPL-47XX Isolated Monitoring Circuits for 2-Wire ISDN Telephone Line.
ISOLATION
BARRIER
EMI FILTER
V
RECTIFIER
AND
FILTER
O
115/230
VAC
SWITCHING
ELEMENT
AND
CURRENT
LIMITER
GND 2
1
2
ERROR
FEEDBACK
VIA CNR200
CONTROL
CIRCUIT
SOFT START
COMMAND
HCPL-4701
INTERRUPT FLAG
POWER DOWN
POWER
SUPPLY
FILTER
CAPACITOR
1
2
1
Figure 11. Typical Optical Isolation Used for Power-Loss Indication and Regulation Signal Feedback.
RECOMMENDED V
FILTER
CC
100 Ω
1
2
8
7
V
V
CC
+
0.1 µF
10 µF
R
L
6
5
O
3
4
HCPL-4701 OR HCPL-4731
Figure 12. Recommended Power Supply Filter for HCPL-47XX Optocouplers.
AGILENT [ AGILENT TECHNOLOGIES, LTD. ]
