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R07

CPC7583

2. Functional Description

2.1 Introduction

The CPC7583 has the following states:

other switches open.

other switches open.

other switches open.

other switches open.

SW5, and SW6 closed, all other switches open.

test. SW5, SW6, SW7, and SW8 closed, all other

switches open (only on the xC and xD versions).

See “Truth Tables” on page 12 for more information.

The CPC7583 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 ringing

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 line break switches SW1 and

matching characteristics. The ringing switch SW4 has

a minimum open contact breakdown voltage of 465 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 CPC7583 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 the integrated SCR.

Power-cross potentials are also reduced by the current

limiting and thermal shutdown circuits.

To protect the CPC7583 from an overvoltage fault

condition, the use of a secondary protector is required.

The secondary protector must limit the voltage seen at

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 CPC7583 will meet all

relevant ITU, LSSGR, TIA/EIA and IEC protection

requirements.

The CPC7583 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. The battery voltage is also used by the

CPC7583 as a reference for the integrated protection

circuit. In the event of a loss of battery voltage, the

CPC7583 enters the all-off state.

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

relative to the state of the loop break switches SW1

and SW2 using simple logic-level input. This is

referred to as a make-before-break or

break-before-make operation. When the line break

switch contacts (SW1 and SW2) are closed (or made)

before the 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 the ringing access contacts

(SW3 and SW4) are opened (broken) before the line

break switch contacts (SW1 and SW2) are closed

(made). With the CPC7583, the make-before-break

and break-before-make operations can easily be

selected by applying the proper sequence of logic

The logic sequences for either mode of operation 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

explanations are given in “Truth Tables” on page 12.