DS_1x22_017
73M1822/73M1922 Data Sheet
4.3 Over-Voltage and EMI Protection
Over-voltage/over-current protection is required to meet worst-case conditions for target countries.
UL1950, EN60950, IEC 60950, ITU-T K.20/K.21 and GR-1089-CORE specifications define the protection
requirements for many countries. A single design can be implemented to meet all these requirements.
Figure 12 shows a recommended protection circuit topology. Fuse (F1) should be rated for 600 V operation
and the bidirectional thyristor (E1) should have a minimum break-over of 275 V and be able to survive a 100
A fast transient. In addition to over-voltage and current protection, the line-interface designer should make
provisions to prevent EMI emissions and susceptibility. Figure 12 also illustrates how L1, L2, C35, C36 and
C42 can provide this suppression. The ferrite beads, L1 and L2, should be capable of passing 200 mA and
have an impedance of 2000 Ω at 100 MHz. C35, C36 and C42 should be 220 pF and rated for a
breakdown voltage greater than the highest isolation voltage that is required for country compatibility. C35
and C36 should be returned to an earth ground. EMI suppression is dependent on the physical design of
the overall circuit and not all the suppression components may be needed in every design and application.
The values shown are typical and should be optimized for a particular design.
L1
Ω
F1
2000
@ 100 MHz
J1
TR600-150
T
6
5
4
3
2
1
C42
220 pF,
300 V
E1
P3100SBRP
R
L2
2000
C35
Ω
@ 100 MHz
RJ-11
C36
220 pF, 3000 V
220 pF, 3000 V
Figure 12: Suggested Over-voltage Protection and EMI Suppression Circuit
Table 27: Reference Bill of Materials for Figure 12
Reference
Part Description
Bidirectional thyristor, 275V/ 100A
150mA, 600V PTC resettable fuse
2 KΩ @ 100 MHz, 200 mA min, 0805
220 pF, 3000 V
Source
Example MFR P/N
TB3100H-13-H
E1
Diodes, Inc.
Bourns
F1
MF-R015/600 or equivalent
MPZ2012S601A
L1,L2
C36, C35
C42
Steward/TDK
TDK
C4532COG3F221K
VJ1206Y221KXEAT5Z
Vishay
220 pF, 300 V
Rev. 1.6
31
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
