CPC7583
12 www.clare.com Rev. 2.0 9/16/2002
2. Functional Description
2.1 Introduction
The CPC7583 has the following states:
•Idle/talk. Loop break s witches SW1, and SW2
closed, all other switches open.
•Ringing. Ringing switches SW3, SW4 closed, all
other switches open.
•TESTout. Testout s witches SW5, SW6 closed, all
other switches open.
•Ringing generator test. SW7, SW8 closed, all
other switches open.
•TESTin. Testin s w itches SW9 and SW10 closed.
•Simulta neous TESTin and TESTout. SW9, SW10,
SW5, and SW6 closed, all other switches open.
•Simultaneous test out and ringing generator
test. SW5, SW6, SW7, and SW8 closed, all other
switches open (only on the xC and xD v ersions).
•All Off . All switches open.
See “Truth Tables” on page 10 for more information.
The CPC7583 offers break-before-make and make-
before-break switching with simple logic-lev el input
control. Solid-state s witch construction means no
impulse noise is generated when s witching during ring
cadence or ring trip, eliminat ing the need for external
zero-cross switching circuitry. State-control is via
logic-le vel input so no additional driver circuit ry is
required. The line break switches SW1 and SW2 are
linear switches that hav e exceptionally low RON and
e xcellent matching characteristics . The ringing access
switch SW4 has an open contact breakdown voltage
rating of g reat er t han 480 V. This is sufficiently high,
with proper protection, to preve nt br eakdown in the
presence of a transient fault condition (i.e . , p assing
the transient on to t he ring generato r).
Integr ated int o the CPC7583 is a diode bridge/SCR
clamping circuit, current limiting , and a th ermal shut-
down mechanism t o provide protection to the SLIC
de vice during a fault condition. Positive and negative
surges are reduced by the current limiting circuitry and
hazardous potentials are div erted to ground via diodes
and the integrat ed SCR. Power-cross tr ansients are
also reduced b y the curr ent limit ing and t hermal shut-
down circuits .
To protect the CPC7583 from an overvoltage fault
condition, the use of a secondary protector is required.
The secondary protector must limit the v oltage seen at
the TLINE and RLINE terminals to a le vel below the
maximum breakdown voltage of the switches. To min-
imize the stre ss on the solid-state contacts, use of a
f oldback or crowbar type secondary protector is rec-
ommended. With proper selection of the secondary
protector, a line card using the CPC7583 will meet all
rele vant ITU, LSSGR, FCC and UL protection require-
ments.
The CPC7583 operates from a +5 V supply only. This
gives the device e xtremely low idle and active power
dissipation and allows use with virtually any range of
battery voltag e . A battery voltage is also used by the
CPC7583 as a ref erence for the integrated protect ion
circuit. In the event of a loss of battery vo lt age , the
CPC7583 enters the all-off st ate.
2.2 Switch Logic
The CPC7583 provides , when switching from the ring-
ing state to the idle/talk state, the ability to control the
release timing of the ringing switches SW3 and SW4
relativ e to the state of the loop break s wit ches SW1
and SW2 using simple logic-level input. This is
ref erred to a make-bef ore-break or break-before-mak e
operation. When the line br eak switch contacts (SW1
and SW2) are closed (or made) before the ringing
access s wit ch contacts (SW3 a nd SW4) are opened
(or broken), this is referred to make-before-break
operation. Break-before-make operation occurs when
the ringing access contacts (SW3 and SW4) are
opened (brok en) before the line break s witch contacts
(SW1 and SW2) are closed (made). With t he
CPC7583, the make-before-break and break-before-
make operations can easily be selected by applying
the proper sequence of logic inputs to INTESTout,
INRINGING, and INTESTin.
The logic sequences for either mode of operation are
given in “Make-Before-Break Operation (Ringing to Idle/
Talk Transition)” on page 13 and “Break-Before-Make Oper-
ation (Ringing to Idle/Talk Transition)” on page 13. Logic
states and explanations are given in “Truth Tables” on
page 10.
Break-before-make operation can also be achieve d
using pin 13 (TSD) as an input. In “Break-Before-Make
Operation (Ringing to Idle/Talk Transition)” on page 13,
lines 2 and 3, it is possible to induce the s wit ches to
the all-off state by grounding pin 13 (TSD) instead of
applying logic input to the pins. This has the effect of
ov erriding the logic inputs and f orcing the de vice to the
all-off state. Hold th is input state f or 25 ms. During this
hold period, toggle the inputs from the ringing state to
the idle/talk state . After the 25 ms, release pin 13