14

Figure 12. Recommended Power Supply Filter for HCPL-47XX Optocouplers.

RECOMMENDED VCC FILTER

8

0.1 µF

VCC

10 µF

+

100

Ω

VO

RL

7

6

5

1

2

3

4

HCPL-4701 OR HCPL-4731

Figure 10. HCPL-47XX Isolated Monitoring Circuits for 2-Wire ISDN Telephone Line.

Figure 11. Typical Optical Isolation Used for Power-Loss Indication and Regulation Signal Feedback.

115/230

VAC

EMI FILTER

AND

CURRENT

LIMITER

ISOLATION

BARRIER

VO

GND 2

1

12

12

SOFT START

COMMAND

INTERRUPT FLAG

POWER DOWN

POWER

SUPPLY

FILTER

CAPACITOR

SWITCHING

ELEMENT

RECTIFIER

AND

FILTER

CONTROL

CIRCUIT

ERROR

FEEDBACK

VIA CNR200

HCPL-4701

2-WIRE

ISDN

LINE

PROTECTION

CIRCUIT

P0WER

SUPPLY

SECONDARY

POWER

EMERGENCY

POWER

PRIMARY–SECONDARY

POWER ISOLATION

BARRIER

VAC

PRIMARY

TELEPHONE LINE

ISOLATION BARRIER

HCPL-4731

HCPL-4701

SWITCHED–

MODE

POWER

SUPPLY

RECEIVE

TRANSMIT

LINE POLARITY

LINE PRESENCE

SECONDARY/

EMERGENCY

POWER

VCC

VCC – RETURN

TELEPHONE

LINE

INTERFACE

CIRCUIT

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.