October 2010 Doc ID 8627 Rev 4 1/12
12
LCDP1521
Dual-line programmable transient voltage suppressor for
SLIC protection
Features
■dual-line programmable transient voltage
suppressor
■wide negative firing voltage range
■VMGL = -150 V max.
■low dynamic switching voltages:
VFP and VDGL
■low gate triggering current: IGT = 5 mA max.
■peak pulse current: IPP = 20 A (10/1000 µs)
■holding current: IH = 150 mA min.
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 meet various
standards such as UL1950, IEC 950 / CSA
C22.2, UL1459 and FCC part68.
■Trisils have UL94 V0 approved resin.
■Trisils are UL497B approved (file: E136224).
Description
This device has been designed to protect 2 new
high voltage, as well as classical SLICs against
transient overvoltages.
Positive overvoltages are clamped by 2 diodes.
Negative surges are suppressed by 2 thyristors,
their breakdown voltage being referenced to
-VBAT through the gate.
This component presents a very low gate
triggering current (IGT) to reduce the current
consumption on printed circuit boards during the
firing phase.
TM: Trisil is a trademark of STMicroelectronics
Figure 1. Functional diagram
SO-8
TIP 1 RING 1
TIP 2 RING 2
GATE
GATE
GND
GND
1
2
3
4
8
7
6
5
www.st.com
Compliant with the following standards LCDP1521
2/12 Doc ID 8627 Rev 4
1 Compliant with the following standards
Table 1. Compliant with the following standards
Standard Peak surge
voltage (V)
Voltage
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
31
40
GR-1089 Core
Second level 5000 2/10 µs 500 2/10 µs 62
GR-1089 Core
Intra-building 1500 2/10 µs 100 2/10 µs 7
ITU-T-K20/K21 6000
1500 10/700 µs 150
37.5 5/310 µs 200
20
ITU-T-K20
(IEC 61000-4-2)
8000
15000 1/60 ns ESD contact discharge
ESD air discharge
0
0
VDE0433 4000
2000 10/700 µs 100
50 5/310 µs 120
40
VDE0878 4000
2000 1.2/50 µs 100
50 1/20 µs 27
0
IEC 61000-4-5 4000
4000
10/700 µs
1.2/50 µs
100
100
5/310 µs
8/20 µs
120
27
FCC Part 68, lightning
surge type A
1500
800
10/160 µs
10/560 µs
200
100
10/160 µs
10/560 µs
43
32
FCC Part 68, lightning
surge type B 1000 9/720 µs 25 5/320 µs 0
LCDP1521 Characteristics
Doc ID 8627 Rev 4 3/12
2 Characteristics
Figure 2. Electrical characteristics (Tamb = 25 °C)
Table 2. Thermal resistance
Symbol Parameter Value Unit
Rth (j-a) Junction to ambient 170 °C/W
VRM
VR
IPP
IH
IR
IRM
VF
I
V
Symbol Parameter
IGT Gate triggering current
IHHolding current
IRM Reverse leakage current line / GND
IRG Reverse leakage current gate / line
VRM Reverse voltage line / GND
VGT Gate triggering voltage
VFForward drop voltage line / GND
VFP Peak forward voltage line / GND
VDGL Dynamic switching voltage gate / Line
VGATE Gate / Gnd voltage
VRG Reverse voltage gate / Line
C Capacitance line / GND
Table 3. Absolute ratings (Tamb = 25 °C, unless otherwise specified)
Symbol Parameter Value Unit
IPP Peak pulse current(1)
10/1000 µs
8/20 µs
10/560 µs
5/310 µs
10/160 µs
1/20 µs
2/10 µs
20
60
20
25
30
60
70
A
ITSM
Non repetitive surge peak on-state
current (50 Hz sinusoidal)
t = 10 ms
t = 1 s
5
3.5 A
I2tI
2t value for fusing (50 Hz sinusoidal) t = 10 ms 0.125 A2s
IGSM Maximum gate current (50 Hz sinusoidal) t = 10 ms 2 A
VMLG
VMGL
Maximum voltage LINE/GND
Maximum voltage GATE/LINE
-40 °C < Tamb < +85 °C
-40 °C < Tamb < +85 °C
-150
-150 V
Tstg
Tj
Storage temperature range
Maximum junction temperature
- 55 to + 150
150 °C
TL Maximum lead temperature for soldering during 10 s 260 °C
1. For pulse waveform see Figure 3.
Characteristics LCDP1521
4/12 Doc ID 8627 Rev 4
Figure 3. Repetitive peak pulse current
100
50
%I
PP
t
t
t
rp
0
tr: rise time (µs)
tp: pulse duration (µs)
ex: Pulse waveform 10/1000 µs
tr= 10 µs tp= 1000 µs
Table 4. Parameters related to the diode line / GND (Tamb = 25 °C)
Symbol Test conditions Max Unit
VFIF = 1 A t = 500 µs 2 V
VFP(1)
10/700 µs
1.2/50 µs
2/10 µs
1.5 kV
1.5 kV
2.5 kV
RS = 110 Ω
RS = 60 Ω
RS = 245 Ω
IPP = 10 A
IPP = 15 A
IPP = 10 A
5
10
20
V
1. See Figure 5: Test circuit for VFP and VDGL parameters. RS is the protection resistor located on the line card.
Table 5. Parameters related to the protection thyristor
(Tamb = 25°C unless otherwise specified)
Symbol Test conditions Min Max Unit
IGT VGND / LINE = -48 V 0.1 5 mA
IHVGATE = -48 V(1) 150 mA
VGT At IGT 2.5 V
IRG
VRG = -150 V
VRG = -150 V
Tc = 25 °C
Tc = 85 °C
5
50 µA
VDGL
VGATE = -48 V(2)
10/700 µs
1.2/50 µs
2/10 µs
1.5 kV
1.5 kV
2.5 kV
RS = 110 Ω
RS = 60 Ω
RS = 245 Ω
IPP = 10 A
IPP = 15 A
IPP = 10 A
5
10
20
V
1. See Figure 4: Functional holding current (IH) test circuit: go no-go test
2. See Figure 5: Test circuit for VFP and VDGL parameters. The oscillations with a time duration lower than 50 ns are not taken
into account
Table 6. Parameters related to diode and protection thyristor
(Tamb = 25 °C, unless otherwise specified)
Symbol Test conditions Typ. Max. Unit
IRM
VGATE / LINE = -1 V VRM = -150 V
VGATE / LINE = -1 V VRM = -150 V
Tc = 25 °C
Tc = 85 °C
5
50 µA
CVR = 50 V bias, VRMS = 1 V, F = 1 MHz
VR = 2 V bias, VRMS = 1 V, F = 1 MHz
20
48 pF
LCDP1521 Test circuits
Doc ID 8627 Rev 4 5/12
3 Test circuits
3.1 Functional holding current (IH): go no-go test
Figure 4. Functional holding current (IH) test circuit: go no-go test
This is a go no-go test, which confirms the holding current (IH) level in a functional test circuit.
3.1.1 Test procedure
●Adjust the current level at the IH value by short circuiting the D.U.T.
●Fire the D.U.T. with a surge current: IPP = 10 A, 10/1000 µs.
The D.U.T. will come back to the off-state within a duration of 50 ms max.
3.2 Test circuit for VFP and VDGL parameters
Figure 5. Test circuit for VFP and VDGL parameters
R
V
BAT = -100 V
Surge generator
D.U.T
C2
R4
R3
TIP
RING
GND
VP
R2
R1
L
C1
(VPis defined in unloaded condition)
Technical information LCDP1521
6/12 Doc ID 8627 Rev 4
4 Technical information
Figure 6. LCDP1521 concept behavior
Figure 6 shows the classic protection circuit using the LCDP1521 crowbar concept. This
topology has been developed to protect the new high voltage SLICs. This supports the
programming of 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.
The capacitor C is used to speed up the crowbar structure firing during the fast surge edges.
This minimizes 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 to the LCDP1521 Gate pin and to the
reference ground track (or plan). The optimized value for C is 220 nF.
The series resistors Rs1 and Rs2 in Figure 6 represent the fuse resistors or the PTC which
are mandatory to withstand the power contact or the power induction tests imposed by the
Table 7. Test circuit component values
Pulse (µs) VpC1C2LR
1R2R3R4IPP Rs
trtp(V) (μF) (nF) (μH) (Ω)(Ω)(Ω)(Ω)(A)(Ω)
10 700 1500 20 200 0 50 15 25 25 10 110
1.25015001 33 0 761325251560
2 10 2500 10 0 1.1 1.3 0 3 3 10 245
VRing
GND
Gate
TIP
RING
GND
-Vbat
C
Rs1
Rs2
L 1
L 2
V Tip
Th1 D1
T1
IG ID1
LCDP1521 Technical information
Doc ID 8627 Rev 4 7/12
various country standards. Taking into account this fact, the actual lightning surge current
flowing through the LCDP is equal to:
Isurge = Vsurge / (Rg + Rs)
With:
Vsurge = peak surge voltage imposed by the standard.
Rg = series resistor of the surge generator
Rs = series resistor of the line card (equivalent to PTC + R in Figure 7)
Example: For a line card with 60 Ω of series resistors, which has to be qualified under
GR-1089 Core 1000 V, 10/1000µs surge, the actual current through the LCDP1521 is equal
to:
Isurge = 1000 / (10 + 60) = 14 A
The LCDP1521 is particularly optimized for the new telecom applications such as the fiber in
the loop, the WLL, and the remote central office. In this case the operating voltages are
smaller than in the classic system. This makes the high voltage SLICs particularly suitable.
The schematics of Figure 7 show the topologies most frequently used for these applications.
Figure 7. Protection of high voltage SLICs
LC D Pxxxx
SLIC 1
-Vbat
PTC or Fuse
PTC or Fuse
R
R
Line 1
PTC or Fuse
PTC or Fuse
Line 2
Ring relay 1
RING
TIP
SLIC 2
R
R
Ring relay 2
Technical information LCDP1521
8/12 Doc ID 8627 Rev 4
Figure 8. Surge peak current versus overload duration.
Figure 9. Relative variation of holding current versus junction temperature
0.01 0.10 1.00 10.00 100.00 1000.00
0
1
2
3
4
5
6
7
t(s)
ITSM(A)
F=50Hz
Tj initial=25°C
-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
Tj ( °C )
IH ( Tj ) / IH ( Tj=25°C )
LCDP1521 Ordering information scheme
Doc ID 8627 Rev 4 9/12
5 Ordering information scheme
Figure 10. Ordering information scheme
LCDP 15 2 1 RL
Line card dual protection
Holding current
15 = 150 mA
Version
2 = devices protected
Package
1 = SO-8
Packaging
Blank = Tube
RL = tape and reel
Package information LCDP1521
10/12 Doc ID 8627 Rev 4
6 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 11. Footprint, dimensions in mm (inches)
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
k0° 8°0° 8°
ppp 0.10 0.004
E1
D
8
4
1
5
E
e
A
A2
bA1
ppp C
C
k
h x 45°
L
L1
Seating
Plane
C
6.8
(0.268)
4.2
(0.165)
1.27
(0.050)
0.6
(0.024)
LCDP1521 Ordering Information
Doc ID 8627 Rev 4 11/12
7 Ordering Information
8 Revision history
Table 9. Ordering information
Order code Marking Package Weight Base qty Delivery mode
LCDP1521 CDP152 SO-8 0.08 g 100 Tube
LCDP1521RL(1)
1. Preferred device
2500 Tape and reel
Table 10. Document revision history
Date Revision Changes
March 2002 1 Initial release.
24-Jun-2005 2 Peak pulse current changed from 15 to 20 A (10/1000 µs)
07-Feb-2006 3 Added footnote to ordering information table
20-Oct-2010 4 Updated ECOPACK statement. Updated trademark statement.
LCDP1521
12/12 Doc ID 8627 Rev 4
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