CPC7582_1 Datasheet, PDF (12/19 Pages) Clare, Inc. – Line Card Access Switch

CPC7582
2. Functional Description
2.1 Introduction
2.1.1 CPC7582xA/B Logic States
• Talk. Break switches SW1 and SW2 closed, ringing
switches SW3 and SW4 open, and test switches
SW5 and SW6 open.
• Ringing. Break switches SW1 and SW2 open,
ringing switches SW3 and SW4 closed, and test
switches SW5 and SW6 open.
• Test. Break switches SW1 and SW2 open, ringing
switches SW3 and SW4 open, and loop test
switches SW5 and SW6 closed.
• All off. Break switches SW1 and SW2 open, ringing
switches SW3 and SW4 open, and test switches
SW5 and SW6 open.
2.1.2 CPC7582xC Logic States:
• Talk. Break switches SW1 and SW2 closed, ringing
switches SW3 and SW4 open, and test switches
SW5 and SW6 open.
• Ringing. Break switches SW1 and SW2 open,
ringing switches SW3 and SW4 closed, and test
switches SW5 and SW6 open.
• Test/Monitor. Break switches SW1 and SW2
closed, ringing switches SW3 and SW4 open, and
test switches SW5 and SW6 closed.
• Ringing Test. Break switches SW1 and SW2 open,
ringing switches SW3 and SW4 closed, and test
switches SW5 and SW6 closed.
• All off. Break switches SW1 and SW2 open, ringing
switches SW3 and SW4 open, and test switches
SW5 and SW6 open.
The CPC7582 offers break-before-make and make-
before-break switching from the ringing state to the
talk state with simple logic-level input control.
Solid-state switch construction means no impulse
noise is generated when switching during ring
cadence or ring trip, eliminating the need for external
zero-cross switching circuitry. State control is via
logic-level input so no additional driver circuitry is
required. The linear break switches SW1 and SW2
have exceptionally low R_ON and excellent matching
characteristics. The ringing switch SW4 has a
minimum open contact breakdown voltage of 480 V.
This is sufficiently high, with proper protection, to
prevent breakdown in the presence of a transient fault
condition (i.e., passing the transient on to the ringing
generator).
Integrated into the CPC7582 is an over voltage
clamping circuit, active current limiting, and a thermal
shutdown mechanism to provide protection to the
SLIC device during a fault condition. Positive and
negative surges are reduced by the current limiting
circuitry and hazardous potentials are diverted to
ground via diodes and, in xA/C parts, an integrated
SCR. Power-cross potentials are also reduced by the
current limiting and thermal shutdown circuits.
To protect the CPC7582 from an overvoltage fault
condition, use of a secondary protector is required.
The secondary protector must limit the voltage seen at
the tip and ring terminals to a level below the
maximum breakdown voltage of the switches. To
minimize the stress on the solid-state contacts, use of
a foldback or crowbar type secondary protector is
recommended. With proper selection of the secondary
protector, a line card using the CPC7582BC will meet
all relevant ITU, LSSGR, TIA/EIA and IEC protection
requirements.
The CPC7582 operates from a +5 V supply only. This
gives the device extremely low idle and active power
consumption and allows use with virtually any range of
battery voltage. Battery voltage is also used by the
CPC7582 as a reference for the integrated protection
circuit. In the event of a loss of battery voltage, the
CPC7582 enters the all-off state.
2.2 Switch Logic
The CPC7582 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
relative to the state of the break switches SW1 and
SW2 using simple logic-level inputs. This is referred to
as make-before-break or break-before-make
operation. When the break switch contacts (SW1 and
SW2) are closed (or made) before the ringing switch
contacts (SW3 and SW4) are opened (or broken), this
is referred to as make-before-break operation.
Break-before-make operation occurs when the ringing
contacts (SW3 and SW4) are opened (broken) before
the break switch contacts (SW1 and SW2) are closed
(made). With the CPC7582, the make-before-break
and break-before-make operations can easily be
selected by applying logic-level inputs to the device.
The logic sequences for these modes of operation are
given in “Make-Before-Break Operation for All
Versions (Ringing to Talk Transition)” on page 13,
“Break-Before-Make Operation CPC7582xA/B
(Ringing to Talk Transition)” on page 13, and
“Break-Before-Make Operation for all Version (Ringing
to Talk Transition)” on page 14. Logic states and input
control settings are given in “CPC7582xA/B Truth
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