
SIDACtor
Data Book
SIDACtor Selection Criteria
Teccor Electronics
(972) 580-7777
5 - 5
T
$%$
When selecting a SIDACtor, the following criteria should be used:
Off-state Voltage (V
DRM
)
The V
DRM
of the SIDACtor must be greater than the maximum operating voltage of the
circuit that the SIDACtor is protecting.
Example 1: For a POTS (Plain Old Telephone Service) application, convert the maximum
operating ring voltage (150V
RMS
) to a peak voltage and add the maximum DC bias
of the central office battery:
150V
RMS
√
2 + 56.6V
PK
= 268.8V
PK
∴
V
DRM
>268.8V
Example 2: For an ISDN application, add the maximum voltage of the DC power supply to the
maximum voltage of the transmission signal:
150V
PK
+ 3V
PK
= 153V
PK
∴
V
DRM
>153V
Switching Voltage (V
S
)
The V
S
of the SIDACtor should be equal to or less than the instantaneous peak
voltage rating of the component it is protecting.
Example 1: V
S
≤
V
Relay Breakdown
Example 2: V
S
≤
SLIC V
PK
Peak Pulse Current (I
PP
)
For circuits that do not require additional series resistance, the surge current rating
(I
PP
) of the SIDACtor should be greater than or equal to the surge currents associated
with the lightning immunity tests of the applicable regulatory requirement (I
PK
).
I
PP
≥
I
PK
For circuits that utilize additional series resistance, the surge current rating (I
PP
) of the
SIDACtor should be greater than or equal to the
available
surge currents associated
with the lightning immunity tests of the applicable regulatory requirement (I
PK(available)
).
I
PP
≥
I
PK(available)
The maximum available surge current is calculated by dividing the peak surge voltage
(V
PK
) by the total circuit resistance (R
TOTAL
).
I
PK(available)
= V
PK
/R
TOTAL
For longitudinal surges (TIP-GND, RING-GND), R
TOTAL
is calculated for both TIP and
RING.
R
SOURCE
= V
PK
/I
PK
R
TOTAL
= R
TIP
+ R
SOURCE
R
TOTAL
= R
RING
+ R
SOURCE