CPC7583_12 Datasheet, PDF (15/19 Pages) IXYS Corporation – Line Card Access Switch

INTEGRATED CIRCUITS DIVISION
CPC7583
Break-before-make operation can also be achieved
using the T_SD pin as an input. In “Break-Before-Make
Operation (Ringing to Talk Transition)” on page 15, lines 2
and 3, it is possible to induce the switches to the all-off
state by grounding T_SD instead of applying input to the
logic pins. This has the effect of overriding the logic
inputs and forcing the device to the all-off state. For
20 Hz ringing hold this input state for 25 ms. During
this hold period, toggle the inputs from the ringing
state to the talk state. After the 25 ms, release T_SD to
return switch control to the input pins IN_TESTout,
IN_RINGING, IN_TESTin and the latch control pin.
2.2.1 Make-Before-Break Operation (Ringing to Talk Transition)
State IN_RINGING IN_TESTIN IN_TESTOUT Latch
Ringing 1
0
0
Make-
before- 0
0
0
break
0
Talk
0
0
0
Break Ring Ring All Other
T_SD
Timing
Switches Return Access Test
1 and 2 Switch 3 Switch 4 Switches
Floating
-
Off
On
On
Off
SW4 waiting for next
zero-current crossing to turn
off. Maximum time is one-half
of ringing. In this transition
Floating 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.
Floating
Zero-cross current has
occurred
On
Off
Off
Off
2.2.2 Break-Before-Make Operation (Ringing to Talk Transition)
State IN_RINGING IN_TESTIN IN_TESTOUT Latch
Ringing 1
0
0
All off
1
0
1
0
All off
1
0
1
Talk
0
0
0
Break Ring Ring All Other
T_SD
Timing
Switches Return Access Test
1 and 2 Switch 3 Switch 4 Switches
Floating
-
Off
On
On
Off
Hold this state for one-half of
Floating ringing cycle. SW4 waiting for Off
Off
On
Off
zero current to turn off.
Floating
Zero current has occurred.
SW4 has opened
Off
Off
Off
Off
Floating Close break switches
On
Off
Off
Off
2.3 Alternate Break-Before-Make Operation
Note that break-before-make operation can also be
achieved using T_SD as an input. In lines 2 and 3 of the
table “Break-Before-Make Operation (Ringing to Talk
Transition)” on page 15, instead of using the logic input
pins to force the all-off state, force T_SD to ground. This
overrides the logic inputs and also forces the all off
state. Hold this state for one-half of the ringing cycle.
During this T_SD forced all-off state, change the inputs
from the power ringing state (IN_RING = 1, IN_TESTIN = 0,
IN_TESTOUT = 0) to the talk state (IN_RING = 0,
IN_TESTIN = 0, IN_TESTOUT = 0). After the hold period,
release T_SD to return switch control to the input pins
which will set the talk state.
R07
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