SIDACtor
Data Book
Analog Line Cards
Teccor Electronics
(972) 580-7777
3 - 19
R
On-Hook (Relay) Protection
On-hook protection is accomplished by choosing a SIDACtor that meets the following
criteria to ensure proper coordination between the ring voltage and the maximum
voltage rating of the relay to be protected.
V
DRM
>V
BATT
+V
RING
V
S
≤
V
Relay Breakdown
This criterion is typically accomplished using two P2600S
_
(where _ denotes the surge
current rating) SIDACtors connected from TIP to GND and RING to GND. However
those who choose to use relays such as Lucent
’
s LCAS (Line Card Access Switch)
should consider the P1200S
_
from TIP to GND and the P2000S
_
from RING to GND.
Off-Hook (SLIC) Protection
Off-hook protection is accomplished by choosing a SIDACtor that meets the following
criteria to ensure proper coordination between the supply voltage (V
REF
) and the
maximum voltage rating of the SLIC to be protected.
V
DRM
>V
REF
V
S
≤
V
SLIC Breakdown
This criterion can be accomplished a variety of different ways. For applications that
use an external ring generator and a fixed battery voltage, two P0641S_ (or P0721S
_
depending on the value of V
REF
) SIDACtors are used; one TIP to GND, one RING to
GND. For applications that use a ring generating SLIC such as AMD
’
s Am79R79, the
P11xx0C
_
can be used.
I
PP
Selection
To ensure the proper surge current rating of the SIDACtor is selected, the I
PP
of the
SIDACtor must be greater than or equal to the maximum available surge current
(I
PK(available)
) of the applicable regulatory requirements. The maximum available surge
current is calculated by dividing the peak surge voltage supplied by the voltage
generator (V
PK
) by the total circuit resistance (R
TOTAL
). The total circuit resistance is
determined by adding the source resistance (R
S
) of the surge generator to the series
resistance that is in front of the SIDACtor on both TIP and RING (R
TIP
and R
RING
).
I
PP
≥
I
PK(available)
I
PK(available)
=V
PK
/R
TOTAL
For metallic surges:
R
TOTAL
=R
S
+R
TIP
+R
RING
For longitudinal surges:
R
TOTAL
=R
S
+R
TIP
R
TOTAL
=R
S
+R
RING