Obsolete Product(s) - Obsolete Product(s)
SSRP105B1
2/6
Fig. 1: Topology of the classical line card protection.
APPLICATION INFORMATION
Fig. 2: Classical use of the SSRP105B1.
The classical line card requires protection before the
ring relay and a second one for the SLIC (
figure 1
).
The use of new SLICs with integrated ring
generator or board based on solid-state ring relay
suppresses this second protection (
figure 2
).
Then, the only remaining stage, located between
the line and the ring relay, has to optimize the
protection.
The classical symmetrical first stage protector
becomes not sufficient to avoid any circuit
destruction during surges.
The SSRP105B1 device takes into account this
fact and is based on asymmetrical voltage
characteristics (
figure 3a
). The ring signal being
shifted back by the battery voltage, the
SSRP105B1 negative breakover value V
BO-
is
greater than the positive one V
BO+
. This point
guarantees a protection operation very close to the
peak of the normal operating voltage without any
disturbance of the ring signal.
Fig. 3: SSRP105B1 electrical characteristics.
VBO-
I
V
V
BO+
a: Line to ground characteristics.
VBO-
I
V
V
BO+
b: Line to line characteristics.
In addition with the 2 crowbar functions which
perform the protection of both TIP and RING lines
versus ground, a third cell assumes the differential
mode protection of the SLIC. The breakover
voltage values of this third cell are the same for
both positive and negative parts of the
characteristics and are equivalent to the negative
breakover voltage value of the TIP and RING lines
versus GND cells (
figure 3b
).
PTC
PTC
R
R
SLIC
(*)
TIP
RING
SSRP105B1
(*) SLIC with integrated ring generator or Solid-State Relay
LINE
1st
stage
2nd
stage
PTC
PTC
R
R
SLIC
Ring generator
±V
RING
VRINGBAT
TIP
RING
