L7582 Datasheet, PDF (1/16 Pages) Agere Systems – Tip Ring Access Switch

Data Sheet
November 1999
L7582 Tip Ring Access Switch
Features
s Small size/surface-mount packaging
s Monolithic IC reliability
s Low impulse noise
s Make-before-break, break-before-make operation
s Clean, bounce-free switching
s Low, matched ON-resistance
s Built-in current limiting, thermal shutdown, and
SLIC protection
s 5 V only operation, very low power consumption
s Battery monitor, all OFF state upon loss of battery
s No EMI
s Latched logic level inputs, no drive circuitry
s Only one external protector required
Applications
s Central office
s DLC
s PBX
s DAML
s HFC/FITL
Description
The L7582 Tip Ring Access Switch is a monolithic
solid-state device that provides the switching
functionality of a 2 form C switch.
The L7582 is designed to provide power ringing
access 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 provides access to the telephone loop
for line test access or message waiting in the PBX
application.
The L7582 has four states: the idle talk state (line
break switches closed, ringing and loop access
switches open), the power ringing state (ringing
access switches closed, line break and loop access
switches open), loop access state (loop access
switches closed, line break and ringing access
switches open), and an all OFF state.
The L7582 offers break-before-make or make-before-
break switching, with simple logic level input control.
Because of the solid-state construction, voltage tran-
sients generated when switching into an inductive
ringing load during ring cadence or ring trip are mini-
mized, possibly eliminating the need for external zero
cross switching circuitry. State control is via logic
level inputs so no additional driver circuitry 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 L7582Axx is a diode bridge/
SCR clamping circuit, current-limiting circuitry, and a
thermal shutdown mechanism to provide protection
to the SLIC device and subsequent circuitry during
fault conditions (see Figure 1). 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 thermal shutdown circuits.