Lucent Technologies Inc.

11

Data Sheet

November 1999

L7582 Tip Ring Access Switch

External Secondary Protector

With the above integrated protection features, only one

overvoltage secondary protection device on the loop

side of the L7582 is required. The purpose of this

device is to limit fault voltages seen by the L7582 so as

not to exceed the breakdown voltage or input-output

isolation rating of the device. To minimize stress on the

L7582, use of a foldback- or crowbar-type device is rec-

ommended. A detailed explanation and design equa-

tions on the choice of the external secondary

protection device are given in the

An Introduction to

tion Note. Basic design equations governing the choice

of external secondary protector are given below:

s

s

s

where:

age of external secondary protector.

of external secondary protector.

voltage of L7582 break switch.

voltage of L7582 ring access switch.

ringing signal.

Series current-limiting fused resistors or PTCs should

be chosen so as not to exceed the current rating of the

external secondary protector. Refer to the manufac-

turer’s data sheet for requirements.

Table 12. Electrical Specifications, Protection Circuitry

* Previous versions of this data sheet specified a Trigger Current of 50 mA minimum. Trigger Current is defined as the minimum current drawn

from tip and ring to turn on the SCR. The specification in this data sheet is Gate Trigger Current, which is defined as the maximum current

that can flow into the battery before the SCR turns on.

† Typical at 25 °C.

‡ Twice ± dynamic current limit of break switches.

§ In some instances, the typical ON-state voltage can range as low as –25 V.

Parameters Related to Diodes (in Diode Bridge)

Parameter

Test Condition

Measure

Min

Typ

Max

Unit

Voltage Drop @ Continuous Cur-

rent (50 Hz/60 Hz)

Apply ±dc current limit

of break switches

Forward

Voltage

——

3

V

Voltage Drop @ Surge

Current

Apply ±dynamic cur-

rent limit of break

switches

Forward

Voltage

—5

—

V

Parameters Related to Protection SCR

Surge Current

—

—

—

—

‡

A

——

—

25

50

mA

Coefficient

—

—

—

–0.5

—

%/°C

Hold Current

—

—

70

—

—

mA

Gate Trigger Voltage

Trigger current

—

—

V

Reverse Leakage Current

——

—

1.0

µA

0.5 A, t = 0.5 µs

2.0 A, t = 0.5 µs

—

—

—

–3

–5

—

—

V

V