73M1866B/73M1966B Data Sheet
DS_1x66B_001
4.4 Isolation Barrier Pulse Transformer
The isolation element used by the 73M1x66B is a standard digital pulse transformer. Several vendors
supply compatible transformers with up to 6000 V ratings. Since the transformer is the only component
crossing the isolation barrier other than EMI capacitors that may be required, it solely determines the
isolation between the PSTN and the FXO’s digital interface. This method of isolation is significantly
superior to other isolation techniques with major advantages in high common mode voltage operation,
lower radiated noise (EMI) and improved operation in noisy environments. Table 29 lists some pulse
transformers compatible with the 73M1x66B. The table also includes low-voltage transformers that offer
low-cost alternatives if such voltages are sufficient.
Table 29: Compatible Pulse Transformer Sources
Company
Number
Sumida
ESMIT 4180
ESMIT 4181
750110001
Wurth Electronics Midcom Inc.
UMEC
TG-UTB01543S
PT79280
Datatronics
AAsupreme
P950003
Table 30 lists some of the typical pulse transformer specifications used by the 73M1x66B. Contact the
manufacturer directly for product information.
Table 30: Pulse Transformer Electrical Characteristics
Parameter
Test Condition
Min
54
–
Nom
60
–
Max
200
6
Tolerance
Unit
μH
pF
Inductance
Interwinding
Capacitance
100 kHz, 10 mVAC, 1-2, Ls.
–
–
–
Turn Ratio
–
–
–
1:1
–
–
±2 %
N/A
Ω
DC Resistance
Primary
Secondary
1 sec
0.25
0.25
–
–
–
–
–
–
Ω
Dielectric Breakdown
Voltage
2000
3750
Vrms
ET Constant
–
–
1.2
6000
–
–
–
–
–
Vμs
V
Surge Test
1.2 x 50 μs
2800
-40
Operating Temperature
–
85
°C
32
Rev. 1.6
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
