CLP200M Datasheet, PDF (6/21 Pages) STMicroelectronics – OVERVOLTAGE AND OVERCURRENT PROTECTION FOR TELECOM LINE

CLP200M
external reference supplies, V_b1 and V_b2 (see fig.5b)..
Fig. 5b : Method to adjust the reference voltage.
Fuse
TIP
FS
RING
Fuse
R sense
TIPL
TIPS
Overcurrent
detector
OR
SW3 SW1
SW4 SW2
OR
Overvoltage
detector
Overvoltage
reference
(+/- 215 V)
Overvoltage
detector
Overvoltage
reference
(+/- 215 V)
GND
Overcurrent
detector
RINGL
R sense
RINGS
2.4 Speech mode
Fig. 6 : Switching by current during speech mode.
I LG
Fuse
TIP
R sense
TIPL
TIPS
1
Overcurrent
detector
Rp
2
OR
SW3 SW1
Overvoltage
detector
Overvoltage
reference
VLG
(+/- 215 V)
FS
GND
-Vbat
External
voltage
reference
1
Rp
2
VB1
VB2
1
Rp
2
ILG
A2
4
-VREF2
5
VREF1
6
VLG
In speech mode (Ring relay in position 1), the pro-
tection is provided by the combination of both
CLP200M and the external voltage reference de-
vice.
In normal conditions, the working point of this cir-
cuit is located in region 4 of A2 curve : the
CLP200M is idle.
When a surge occurs on the line, the external volt-
age reference device clamps at GND or -V_bat re-
spectively for positive and negative surges.
This generates a current which is detected by
R_SENSE and causes the protection to act : the line is
short-circuited to GND.
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The operating point moves to region 5 for positive
surges or region 6 for negative surges.
Once the surge current falls below the switching-
off current I_SWOFF, the CLP200M returns to its in-
itial state (region 4).
Furthermore, the CLP200M switches when an
overvoltage, either positive or negative, occurs
either :
simultaneously on both TIP and RING lines ver-
sus GND.
between TIP and RING.
on TIP (or RING) versus GND.