SMP100MC_05 Datasheet, PDF (6/13 Pages) STMicroelectronics – Trisil™ for telecom equipment protection

Application information
SMP100MC
Figure 8.
Variation of thermal impedance
junction to ambient versus pulse
duration
Zth(j-a)/Rth(j-a)
1.0
0.9 Printed circuit board - FR4,
copper thickness = 35µm,
0.8
recommended pad layout
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
1.E-02
1.E-01
tp(s)
1.E+00
1.E+01
1.E+02
1.E+03
Figure 9.
Relative variation of junction
capacitance versus reverse voltage
applied (typical values)
C [VR] / C [VR=2V]
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
1
10
VR(V)
100
F =1MHz
VOSC = 1VRMS
Tj = 25°C
1000
2
Application information
In wire line applications, analog or digital, both central office and subscriber sides have to be
protected. This function is assumed by a combined series / parallel protection stage
Figure 10. Examples of protection stages for line cards
Ring
relay
Line
Line
Ex. Analog line card
Ex. ADSL line card or terminal
In such a stage, parallel function is assumed by one or several Trisil, and is used to protect
against short duration surge (lightning). During this kind of surges the Trisil limits the voltage
across the device to be protected at its break over value and then fires. The fuse assumes
the series function, and is used to protect the module against long duration or very high
current mains disturbances (50/60Hz). It acts by safe circuits opening. Lightning surge and
mains disturbance surges are defined by standards like GR1089, TIA/EIA IS-968,
ITU-T K20.
6/13
Doc ID 9699 Rev 5