HC5526_03 Datasheet, PDF(16/20 Page) Intersil Corporation – ITU CO/PABX SLIC with Low Power Standby

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HC5526_03 Datasheet, PDF (16/20 Pages) Intersil Corporation – ITU CO/PABX SLIC with Low Power Standby

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HC5526

ring voltages. The protection circuit shown in Figure 21

utilizes diodes together with a clamping device to protect tip

and ring against high voltage transients.

Positive transients on tip or ring are clamped to within a

couple of volts above ground via diodes D1 and D2. Under

normal operating conditions D1 and D2 are reverse biased

and out of the circuit.

Negative transients on tip and ring are clamped to within a

couple of volts below ground via diodes D3 and D4 with the

help of a Surgector. The Surgector is required to block

conduction through diodes D3 and D4 under normal

operating conditions and allows negative surges to be

returned to system ground.

The fuse resistors (RF) serve a dual purpose of being

nondestructive power dissipaters during surge and fuses

when the line in exposed to a power cross.

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