CPC7582

12

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R05

2. Functional Description

2.1 Introduction

2.1.1 CPC7582xA/B Logic States

switches SW3 and SW4 open, and test switches

SW5 and SW6 open.

ringing switches SW3 and SW4 closed, and test

switches SW5 and SW6 open.

switches SW3 and SW4 open, and loop test

switches SW5 and SW6 closed.

switches SW3 and SW4 open, and test switches

SW5 and SW6 open.

2.1.2 CPC7582xC Logic States:

switches SW3 and SW4 open, and test switches

SW5 and SW6 open.

ringing switches SW3 and SW4 closed, and test

switches SW5 and SW6 open.

closed, ringing switches SW3 and SW4 open, and

test switches SW5 and SW6 closed.

ringing switches SW3 and SW4 closed, and test

switches SW5 and SW6 closed.

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

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