Data Sheet
February 2001
L7583A/B/C/D Line Card Access Switch
Features
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Small size/surface-mount packaging
Monolithic IC reliability
Low impulse noise
Make-before-break, break-before-make operation
Clean, bounce-free switching
Low, matched ON-resistance
Built-in current limiting, thermal shutdown, and
SLIC protection
5 V only operation, very low power consumption
Battery monitor, all OFF state upon loss of battery
No EMI
Latched logic level inputs, no driver circuitry
Only one external protector required
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The L7583A/B has seven states: the idle talk state
(line break switches closed, all other switches open),
the power ringing state (ringing access switches
closed, all other switches open), loop access state
(loop access switches closed, all switches open),
SLIC test state (test in switches closed, all other
switches open), simultaneous loop and SLIC
access state (loop and test in switches closed, all
others open), ringing generator test state (ring test
switches closed, all others open), and an all OFF
state. The seven states in the L7583A/B are also in
the L7583C/D, with an additional simultaneous test-
out and ring-test state, making the L7583C/D appro-
priate for digital loop carrier and other Bellcore TR-57
applications.
The L7583 offers break-before-make or make-
before-break switching, with simple logic level input
control. Because of the solid-state construction, volt-
age transients generated when switching into an
inductive ringing lead during ring cadence or ring trip
are minimized, possibly eliminating the need for
external zero cross switching circuitry. State control
is via logic level inputs, so no additional driver cir-
cuitry is required.
The line break switch is a linear switch that has
exceptionally low ON-resistance and an excellent
ON-resistance matching characteristic. The ringing
access switch has a breakdown voltage rating
>480 V which is sufficiently high, with proper protec-
tion, to prevent breakdown in the presence of a tran-
sient fault condition (i.e., passing the transient on to
the ringing generator).
Incorporated into the L7583Axx and L7583Cxx is a
diode bridge/SCR clamping circuit, current-limiting
circuitry, and a thermal shutdown mechanism to pro-
vide protection to the SLIC device and subsequent
circuitry during fault conditions. This is shown in Fig-
ure 1 as version A. Positive and negative lightning is
reduced by the current-limiting circuitry and steered
to ground via diodes and the integrated SCR. Power
cross is also reduced by the current-limiting and ther-
mal shutdown circuits.
Applications
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Central office
DLC
PBX
DAML
HFC/FITL
Description
The L7583A/B/C/D Line Card Access Switch is a
monolithic solid-state device providing the equivalent
switching functionality of three 2 form C switches.
The L7583 is designed to provide power ringing
access, line test access (test out), and SLIC test
access (test in) to tip and ring in central office, digital
loop carrier, private branch exchange, digitally added
main line, and hybrid fiber coax/fiber-in-the-loop ana-
log line card applications. An additional pair of solid-
state contacts are also available to provide access
for testing of the ringing generator.
AGERE [ AGERE SYSTEMS ]
