R02

www.clare.com

11

2.5 Photo-Diode (PD) Output Behavior

Output from the PD pin provides a minimum of 0.2 mA

of photo-diode drive current for the opto-coupler LED

anytime sealing current exceeds 1 mA.

Because LED current is interrupted whenever loop

current is interrupted, the opto-coupler provides an

excellent means of indicating loop availability for

designs with a sealing current requirement.

2.6 On-State Behavior

2.6.1 Typical Conditions

On-state sealing current levels are determined by the

network’s power feed circuit and the loop’s dc

impedance. To compensate for low loop resistance or

very high loop voltage, the CPC1465 limits the

maximum sealing current to 70 mA.

The CPC1465 manages package power dissipation

by shunting excess sealing current through the 2.2 k

Ω

4W power resistor located between the PR+ and PR-

pins.

2.6.2 Over-Voltage Conditions

Potentials in excess of 100 V applied to the tip and

ring interface will cause the CPC1465 to disable the

sealing current hold circuit and enter a standby state

with very little current draw. Once the over-voltage

condition is removed, the CPC1465 automatically

resumes normal operation.