Data Sheet
L8583D Line Card Access Switch
October 2002
Switching Behavior
When switching from the power ringing state to the idle/talk state, via simple logic level input control, the L8583D is
able to provide control with respect to the timing when the ringing access contacts are released relative to the state
of the line break contacts.
Make-before-break operation occurs when the line break switch contacts are closed (or made) before the ringing
access switch contact is opened (or broken). Break-before-make operation occurs when the ringing access contact
is opened before the line break switch contacts are closed.
Using the logic level input pins RING, TESTin, and TESTout, either make-before-break or break-before-make oper-
ation of the L8583D is easily achieved. The logic sequences for either mode of operation are given in Table 13 and
Table 14. See the Truth Table (Table 16) for an explanation of logic states.
When using an L8583D in the make-before-break mode, during the ring-to-idle transition, for a period of up to one-
half cycle at the ringing frequency, the ring break switch and the pnpn-type ring access switch can both be in the on
state. This is the maximum time after the logic signal at INRING has transitioned that the ring access switch is wait-
ing for the next zero current cross, so it can close. During this interval, current that is limited to the dc break switch
current-limit value will be sourced from the ring node of the SLIC.
Table 13. Make-Before-Break Operation—Part I
RIN TESTin TESTout TSD
G
State
Timing
Break
Ring
Ring
All Other
Access
Switches Return
Access
3 and 4 Switch 7 Switch 8 Switches
5 V
0 V
0 V
0 V
0 V
0 V
Float Power
Ringing
Float Make- SW8 waiting for next zero cur-
before- rent crossing to turn off maxi-
break mum time—one-half of ringing.
In this transition state, current
that is limited to the dc break
—
Open
Closed
Closed
Closed
Open
Open
Closed
Open
switch current-limit value will be
sourced from the ring node of the
SLIC.
0 V
0 V
0 V
Float Idle/Talk Zero cross current has occurred.
Closed
Open
Open
Open
11
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
