CPC7583
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2. Functional Description
2.1 Introduction
The CPC7583 has the following st ates:
•Talk. Loop break switches 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 witches 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 versions).
•All Off . All switches open.
See “Truth Tables” on page 12 for more information.
The CPC7583 offers break-before-make and
make-before-break switching from the ringing state t o
the talk state with simple logic level input control.
Solid-state switch construction means no impulse
noise is generated wh en switching during ringing
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 circuitry is
required. The linear line break s witches SW1 and
SW2 have exceptionally low RON and excellent
matching characteristics . The ringing switch SW4 has
a minimum open contact breakdo w n v oltage of 465 V.
This is sufficiently high, wit h proper protection, to
pre vent breakdo wn in the presence of a t ransient fault
condition (i.e., passing the tr ansient on to the ringing
generator).
Integr ated int o the CPC7583 is an ov er voltage
clamping circuit, activ e current limiting, and a thermal
shutdown mechanism to provide protection to the
SLIC de vice during a fault condition. Positive and
negativ e surges are reduced b y the current limiting
circuitry and hazardous potentials are diverted to
ground via diodes and t he integrated SCR.
P ower-cross potentials are also reduced by the current
limiting and thermal shutdown circu its .
To protect the CPC7583 from an o vervoltage 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 sw itches. To
minimize the stress o n the solid-state cont acts, use of
a foldback or crowbar type secondary protector is
recommended. With proper selection of the secondary
protector, a line card using the CPC7583 will meet all
rele vant ITU, LSSGR, TIA/ EI A and I EC prote ction
requirements.
The CPC7583 operates from a +5 V supply only. This
gives the device extremely low idle and a ctive pow er
consumption and allows use wi th virtually any range of
battery voltage. The battery voltage is also used by the
CPC7583 as a ref erence for the integr ated protect ion
circuit. In the ev ent of a loss of bat tery volt age, the
CPC7583 enters the all-off st ate.
2.2 Switch Logic
The CPC7583 provides , when switching from the
ringing state to the 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
referred to as a make-before-break or
break-bef ore-make operation. When the line break
s witch conta cts (SW1 and SW2) are closed ( or made)
bef o re th e ringing access switch contacts (SW3 and
SW4) are opened (broken), this is referred to as
make-before-break operation. Break-before-make
operation occurs when t he ringing access contacts
(SW3 and SW4) are opened (broken) before the line
break s witch cont acts (SW1 and SW2) are closed
(made). With the CPC7583, the make-bef ore -break
and break-before-make op er at ions can easily be
selected by applying the proper sequence of logic
inputs to INTESTout, INRINGING, and INTESTin.
The logic sequences for either mode of operat ion are
given in “Make-Before-Break Operation (Ringing to Talk
Transition)” on page 15 and “Break-Before-Make Operation
(Ringing to Talk Transition)” on page 15. Logic states and
e xplanations are giv en in “Truth Tables” on page 12.
Break-before-make oper at ion can also be achieved
using the TSD pin as an input. In “Break-Before-Make
Operation (Ringing to Talk Transition)” on page 15, lines 2
and 3, it is possib le to induce the s witches to the all-off
state b y grounding TSD instead of applying input to the
logic pins. This has the effect of o verriding the logic
inputs and forcing the de vice t o the all-of f stat e. F or