CLP200M Datasheet, PDF (4/21 Pages) STMicroelectronics – OVERVOLTAGE AND OVERCURRENT PROTECTION FOR TELECOM LINE

CLP200M
APPLICATION CIRCUIT : CLP200M in line card
Fig. 3 : CLP200M in line card
I
Fuse
TIP
R sense
TIPL
TIPS
Overcurrent
detector
OR
SW3 SW1
FS
SW4 SW2
OR
Over voltage
detector
Overvoltage
reference
(+/- 215 V)
Over voltage
detector
Overvoltage
reference
(+/- 215 V)
GND
RING
Fuse
Overcurrent
detector
RINGL
R sense
RINGS
1
Rp
2
1
Rp
2
-Vbat
External
voltage
reference
-Vbat
(*)
TIP
SLIC
RING
Ring
Generator
(*) LCP1511D or THDT series
Figure 3 above shows the topology of a protected
analog subscriber line at the exchange side. The
CLP200M is connected to the ring relay via two
balanced Rp resistors, and to the Subscriber Line
Interface Circuit. A second device is located near
the SLIC : it can be either a LCP1511D or a THDT
series.
These two devices are complementary and their
functions are explained below :
The first stage based on CLP200M manages
the high power issued from the external
surges. When used in ringing mode, the
CLP200M operates in voltage mode and pro-
vides a symmetrical and bidirectional
overvoltage protection at +/-215 V on both TIP
and RING lines. When used in speech mode,
the CLP200M operates in current mode and
the activation current of the CLP200M is ad-
justed by RSENSE.
The second stage is the external voltage refer-
ence device which defines the firing threshold
voltage during the speech mode and also as-
sumes a residual power overvoltage
suppression. This protection stage can be either
a fixed or programmable breakover device. The
THDTxx family acts as a fixed breakover device
while the LCP1511D operates as a programma-
ble protection.
Thanks to this topology, the surge current in the
line is reduced after the CLP200M. Because the
remaining surge energy is low, the power ratings of
Rp, the ring relay contacts and the externalvoltage
reference circuit may be downsized. This results in
a significant cost reduction.
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