CPC7582_1 Datasheet, PDF (13/19 Pages) Clare, Inc. – Line Card Access Switch

CPC7582
Table” on page 10 and “CPC7582xC Truth Table” on
page 11.
2.2.1 Make-Before-Break Operation - All Versions
To use make-before-break operation, change the logic
inputs to the talk state immediately following the
ringing state. Application of the talk state opens the
ringing return switch (SW3) as the break switches
(SW1 and SW2) close. The ringing switch (SW4)
remains closed until the next zero-crossing of the
ringing supply current. While in the make-before-break
state, ringing potentials in excess of the CPC7582
protection circuitry trigger levels will be diverted to
ground.
2.2.2 Make-Before-Break Operation for All Versions (Ringing to Talk Transition)
State
Ringing
Make-
before-
break
Talk
IN_RINGING
1
0
0
IN_TEST LATCH T_SD
Timing
Ringing
Break Return
Switches Switch
(SW3)
Ringing
Switch
(SW4)
Test
Switches
0
-
Off
On
On
Off
SW4 waiting for next zero-current
crossing to turn off. Maximum time is
one-half of the ringing cycle. In this
0
0 Floating transition state, current that is limited to On
Off
On
Off
the dc break switch current limit value
will be sourced from the ring node of the
SLIC.
0
Zero-cross current has occurred
On
Off
Off
Off
2.2.3 Break-Before-Make Operation - CPC7582xA/B
Break-before-make operation of the CPC7582xA/B
can be achieved using two different techniques.
The first method uses manipulation of the IN_RINGING
and IN_TEST logic inputs as shown in
“Break-Before-Make Operation CPC7582xA/B
(Ringing to Talk Transition)” on page 13.
1. At the end of the ringing state apply the all off
state (0, 0). This releases the ringing return
switch (SW3) while the ringing switch remains
on, waiting for the next zero current event.
2. Hold the all off state for at least one-half of a
ringing cycle to assure that a zero crossing event
occurs and that the ringing switch (SW4) has
opened.
Break-before-make operation occurs when the ringing
switch opens before the break switches (SW1 and
SW2) close.
2.2.4 Break-Before-Make Operation CPC7582xA/B (Ringing to Talk Transition)
State
Ringing
All-Off
Break-
Before-
Make
Talk
IN_RINGING
1
1
1
0
IN_TEST LATCH T_SD
Timing
Ringing
Break Return
Switches Switch
(SW3)
Ringing
Switch
(SW4)
Test
Switches
0
-
Off
On
On
Off
Hold this state for at least one-half of the
1
ringing cycle. SW4 waiting for zero
Off
Off
On
Off
current to turn off.
0 Floating
1
SW4 has opened
Off
Off
Off
Off
0
Close Break Switches
On
Off
Off
Off
2.2.5 Break-Before-Make Operation - All Versions
The second break-before-make method for the
CPC7582xA/B is also the only method available for
the CPC7582xC. As shown in “CPC7582xA/B Truth
Table” on page 10 and “CPC7582xC Truth Table” on
page 11, the bidirectional T_SD interface disables all of
R05
www.clare.com
13