February 2012 Doc ID 13397 Rev 4 1/9
9
LCP1531
Programmable transient voltage suppressor for SLIC protection
Features
■Dual programmable transient suppressor
■Wide negative firing voltage range:
VGn = -175 V max.
■Low dynamic switching voltages:
VFP and VDGL
■Low gate triggering current: IGT = 5 mA max
■Peak pulse current: IPP = 37.5 A (5/310 µs)
■Holding current: IH = 150 mA min.
■Low space consuming package
Benefits
■A Trisil™ is not subject to ageing and provides
a fail-safe mode in short circuit for better
protection.
■Trisils are used to help equipment to meet
various standards such as YDT695, and
ITU-T K20/21.
■Trisils are UL94 V0 resin approved and are
UL497B approved [file: E136224]).
Description
These devices are ideally suited to meet the
protection requirement of VoIP SLICs located in
next generation residential gateways. They can
be used for protecting any ringing SLIC since they
meet the protection standard requirements.
Positive overvoltages are clamped by 2 diodes.
Negative surges are suppressed by 2 thyristors,
their breakdown voltage being referenced to -VBAT
through the gate.
These components present a very low gate
triggering current (IGT) to reduce the current
consumption on printed circuit board during the
firing phase.
TM: Trisil is a trademark of STMicroelectronics
Figure 1. LCP1531 functional diagram
SO-8
TIP
Gn
NC
RING
TIP
GND
RING
GND
1
www.st.com
Characteristics LCP1531
2/9 Doc ID 13397 Rev 4
1 Characteristics
Table 1. Standards compliance
Standard
Peak
surge
voltage
(V)
Voltag e
waveform
Required
peak
current
(A)
Current
waveform
Minimum serial
resistor to meet
standard (Ω)
GR-1089 Core First level 2500
1000
2/10 µs
10/1000 µs
500
100
2/10 µs
10/1000 µs
23
30
GR-1089 Core
Second level 5000 2/10 µs 500 2/10 µs 46
GR-1089 Core
Intra-building 1500 2/10 µs 100 2/10 µs 1.7
ITU-T-K20/K21 6000
1500 10/700 µs 150
37.5 5/310 µs 120
0
ITU-T-K20 (IEC 61000-4-2) 8000
15000 1/60 ns ESD contact discharge
ESD air discharge
0
0
IEC 61000-4-5 4000
4000
10/700 µs
1.2/50 µs
100
100
5/310 µs
8/20 µs
67
27
TIA-968-A,
lightning surge type A
1500
800
10/160 µs
10/560 µs
200
100
10/160 µs
10/560 µs
26
17
TIA-968-A,
lightning surge type B 1500 9/720 µs 37.5 5/320 µs 0
Table 2. Thermal resistance
Symbol Parameter Value Unit
Rth(j-a) Junction to ambient 120 °C/W
LCP1531 Characteristics
Doc ID 13397 Rev 4 3/9
Figure 2. Electrical characteristics (definitions)
Figure 3. Pulse waveform
Table 3. Absolute ratings (Tamb = 25 °C, unless otherwise specified)
Symbol Parameter Value Unit
IPP Peak pulse current
10/1000 µs
8/20 µs
10/560 µs
5/310 µs
10/160 µs
1/20 µs
2/10 µs
25
60
32
37.5
45
60
90
A
ITSM
Non-repetitive surge peak on-state current
(50 Hz sinusoidal)
t = 20 ms
t = 200 ms
t = 1 s
16
9
6
A
IGSM Maximum gate current (50 Hz sinusoidal) t = 10 ms 2 A
VGn Negative battery voltage range -175 V
Tstg
Tj
Storage temperature range
Operating junction temperature range
-55 to +150
-40 to +150 °C
TLMaximum lead temperature for soldering during 10 s. 260 °C
V
R
I
PP
I
H
I
R
V
F
I
V
Symbol Parameter
I = Gate triggering current
V = Peak forward voltage LINE / GND
V = Gate triggering voltage
V = Forward drop voltage LINE /GND
I = Reverse leakage current GATE / LINE
I = Holding current
V = Reverse voltage GATE / LINE
V = Dynamic switching voltage GATE / LINE
LINE / GND
C = Capacitance LINE /GND
GT
FP
GT
F
RG
H
RG
DGL
I = Peak pulse current
I = Breakdown current
V = Forward drop voltage
PP
R
F
100
50
%I
PP
tt
rp
0
Pulse waveform
10/1000 µs:
t = 10 µs
t = 1000 µs
r
p
Characteristics LCP1531
4/9 Doc ID 13397 Rev 4
Table 4. Parameters related to the diode LINE / GND (Tamb = 25 °C)
Symbol Test conditions Max. Unit
VFIF = 5 A t = 500 µs 3 V
VFP 10/700 µs VPP = 1.5 kV RS = 15 Ω5V
Table 5. Parameters related to the protection thyristors (Tamb = 25 °C)
Symbol Test conditions Min. Max. Unit
IGT VLINE = -48 V 0.1 5 mA
IHVGn = -48 V 150 mA
IRG VRG = -75 V 5 µA
VDGL
VGn = -48 V(1)
1. The oscillations with a time duration lower than 50 ns are not taken into account.
10/700 µs VPP = 1.5 kV RS = 15 ΩIPP = 27.5 A 7 V
Table 6. Parameters related to diode and protection thyristors (Tamb = 25 °C,)
Symbol Test conditions Typ. Max. Unit
IRVGn / LINE = -1 V VRM = -75 V Tj = 25 °C 5 µA
CVLINE = -50 V, VRMS = 1 V, F = 1 MHz
VLINE = -2 V, VRMS = 1 V, F = 1 MHz
15
35 pF
Table 7. Recommended gate capacitance
Symbol Component Min. Typ. Max. Unit
CGGate decoupling capacitance 100 220 nF
LCP1531 Technical information
Doc ID 13397 Rev 4 5/9
2 Technical information
Figure 4. LCP1531 concept behavior
Figure 4. shows the classical protection circuit using the LCP1531 crowbar concept. This
topology has been developed to protect the new high voltage SLICs. It allows to program the
negative firing threshold while the positive clamping value is fixed at GND.
When a negative surge occurs on one wire (L1 for example) a current IG flows through the
base of the transistor T1 and then injects a current in the gate of the thyristor Th1. Th1 fires
and all the surge current flows through the ground. After the surge when the current flowing
through Th1 becomes less negative than the holding current IH, then Th1 switches off.
When a positive surge occurs on one wire (L1 for example) the diode D1 conducts and the
surge current flows through the ground.
Figure 5. Example of PCB layout based on LCP1531 protection
Figure 5. shows the classical PCB layout used to optimize line protection.
The capacitor C is used to speed up the crowbar structure firing during the fast surge edges.
This allows minimization of the dynamic breakover voltage at the SLIC Tip and Ring inputs
during fast strikes. Note that this capacitor is generally present around the SLIC - Vbat pin.
So to be efficient it has to be as close as possible from the LCP1531 Gate pin and from the
reference ground track (or plan) (see Figure 5.). The optimized value for C is 100 nF.
The series resistors Rs1 and Rs2 designed in Figure 4. represent the fuse resistors or the
PTC which are mandatory to withstand the power contact or the power induction tests
V
Ring
GND
Gn
TIP
RING
GND
-Vbat
C
Rs1
Rs2
L 1
L 2
V Tip
Th1 D1
T1
IG ID1
To
line side
GND To
SLIC side
LCP1531
100 nF
Technical information LCP1531
6/9 Doc ID 13397 Rev 4
imposed by the various country standards. Taking into account this fact the actual lightning
surge current flowing through the LCP1531 is equal to:
I surge = V surge / (Rg + Rs)
With:
V surge = peak surge voltage imposed by the standard.
Rg = series resistor of the surge generator
Rs = series resistor of the line card (e.g. PTC)
The LCP1531 is particularly optimized for the new telecom applications such as the fiber in
the loop, the WLL, the remote central office. In this case, the operating voltages are smaller
than in the classical system. This makes the high voltage SLICs particularly suitable.
The schematics of Figure 6. gives the most frequent topology used for these applications.
Figure 6. Protection of high voltage SLIC
Rs (*) = PTC or fuse resistor
Gn
GND
GND
TIP
RING
-Vbat
LCP1531
100 nF
SLIC
Rs (*)
Rs (*)
Line
Line card
TIP
RING
GND
Figure 7. Surge peak current versus
overload duration
Figure 8. Relative variation of holding
current versus junction
temperature
I (A)
TSM
0
4
8
12
16
20
24
1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03
0
4
8
12
16
20
24
1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03
F=50Hz
Tjinitial=25°C
t(s)
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90
0.7
0.8
0.9
1
1.1
1.2
1.3
T (°C)
j
I [T ] / I [T =25°C]
Hj Hj
LCP1531 Package information
Doc ID 13397 Rev 4 7/9
3 Package information
●Epoxy meets UL94, V0
●Lead-free package
In order to meet environmental requirements, ST offers these devices in different grades of
ECOPACK® packages, depending on their level of environmental compliance. ECOPACK®
specifications, grade definitions and product status are available at: www.st.com.
ECOPACK® is an ST trademark.
Figure 9. SO-8 footprint (dimensions in mm)
Table 8. SO-8 dimensions
Ref.
Dimensions
Millimeters Inches
Min. Typ. Max. Min. Typ. Max.
A1.750.069
A1 0.1 0.25 0.004 0.010
A2 1.25 0.049
b 0.28 0.48 0.011 0.019
C 0.17 0.23 0.007 0.009
D 4.80 4.90 5.00 0.189 0.193 0.197
E 5.80 6.00 6.20 0.228 0.236 0.244
E1 3.80 3.90 4.00 0.150 0.154 0.157
e 1.27 0.050
h 0.25 0.50 0.010 0.020
L 0.40 1.27 0.016 0.050
L1 1.04 0.041
k° 0 8 0 8
ccc 0.10 0.004
E1
D
8
41
5
E
k
h x 45°
L
L1
C
(Seating
Plane) 0.25mm
(Gage Plane)
e
A
A2
bA1
ccc C
C
6.8
(0.268)
4.2
(0.165)
1.27
(0.050)
0.6
(0.024)
Ordering information LCP1531
8/9 Doc ID 13397 Rev 4
4 Ordering information
5 Revision history
Table 9. Ordering information
Order code Marking Package Weight Base qty Delivery mode
LCP1531RL CP153 SO-8 0.08 g 2500 Tape and reel
Table 10. Document revision history
Date Revision Changes
23-Mar-2007 1 First issue.
10-Apr-2008 2 Reformatted for current standards. Changed gate capacitance from
220 nF to 100 nF.
10-Aug-2011 3 Updated standards in Ta b l e 1 .
23-Feb-2012 4 Standardized nomenclature for Gn.
LCP1531
Doc ID 13397 Rev 4 9/9
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