CPC7695 Datasheet, PDF (19/25 Pages) Clare, Inc. – Line Card Access Switch

INTEGRATED CIRCUITS DIVISION
CPC7695
Operation Logic Table (Ringing to Talk Transition): Make-Before-Break
State IN_RINGING IN_TESTin IN_TESTout Latch
Ringing 1
0
0
Make-
Before- 0
0
0
Break
0
Talk
0
0
0
T_SD
Timing
Break
Switches
Ringing
Return
Switch
(SW3)
Ringing
Switch
(SW4)
Test
Switches
-
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
Z
transition state, current that is
limited to the break switch
On
Off
On
Off
DC current limit value will be
sourced from the ring node of
the SLIC.
Zero-cross current has
occurred
On
Off
Off
Off
2.7.2 Break-Before-Make Operation
Break-before-make operation of the CPC7695 can be
achieved using two different techniques.
The first method uses manipulation of the (IN_RINGING,
IN_TESTin, IN_TESTout) logic inputs as shown below in the
“Operation Logic Table (Ringing to Talk Transition):
Break-Before-Make” on page 19.
1. At the end of the Ringing state apply the All-Off
state (1,0,1). This releases the ringing return
switch (SW3) while the ringing switch (SW4)
remains active 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 has opened.
3. Apply inputs for the next desired state. For
theTalk state, the inputs would be (0,0,0).
Break-before-make operation occurs when the ringing
switch opens before the break switches SW1 and
SW2 close.
Operation Logic Table (Ringing to Talk Transition): Break-Before-Make
State IN_RINGING IN_TESTin IN_TESTout Latch T_SD
Timing
Break
Switches
Ringing
Return
Switch
(SW3)
Ringing
Switch
(SW4)
Test
Switches
Ringing 1
0
0
-
Off
On
On
Off
Hold this state for at least
All-Off ^*
1
0
1
one-half of ringing cycle. SW4 Off
Off
On
Off
waiting for zero current to turn off.
Break-
0
Z
Before- ₁
0
1
Make ^*
Zero current has occurred. SW4
has opened
Off
Off
Off
Off
Talk
0
0
0
Break switches close.
On
Off
Off
Off
* For the CPC7695xA/B versions the input pattern (1,1,1) may also be used for the All-Off state.
R01
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