MT8931C
In Figure 21, two types of diodes (germanium 1N270
or schottky MBD301) can be used for D5,6. 1N270
will leave more margin for pulse template and
longitudinal conversion loss. However, MBD301 will
leave more margin for impedance template. All other
components are as described previously for Figure
20.
Proprietary NT&TE Line Interface
For proprietary applications, where stringent
requirements such as ETS 300-012 do not have to
be met, the line interface circuit may be simpler and
consequently less expensive. Figure 23 shows such
a line interface circuit.
R1 should be chosen
according to the transformer selected and the
desired output signal level, typical values of R1 may
The VAC Transformers are available from:
vary from 30Ω to 75Ω.
Numerous types of
transformers may be used, including the following:
Germany
Vacuumschmelze GMBH
Postfach 22 53
APC
8016D (dual with common mode choke)
TEW-5660 (surface mount)
TPW-3852-4 (single)
Filtran
Filtran
Pulse
VAC
D-63412 Hanau
Telephone: (49) 6181 380
PE-65495 (dual)
L4097-X028-80 (single)
Canada
Votron Electronic Ltd.
250 Rayette Road
In Figure 22, everything is the same as in Figure 21,
except transformer pin out.
Concord, Ontario L4K 2G6
Telephone: (905) 669-9870
USA
Vacuumschmelze Corporation
4027 Will Rogers Parkway
Oklahoma City, OK 73108
Telephone: (405) 943-9651
VDD
VDD
VDD
C1
MT8931C
D5
D1
T1
5
4
3
6
LTx
K1
L1
1
VDD
D2
D6
6
7
5
4
Tx+
Tx-
2
R2
R3
+
C2
C3
VBias
T2
9
2
1
Rx-
Rx+
3
4
5
2
1
6
VDD
10
D3
R1
LRx
VSS
K1
C4
Parts List:
D4
C1, 3 = 0.1µF Ceramic
C2 = 10µF Tantalum
C4 = 22pF
VDD
K1
D1-4 = IN914
D5, 6 = IN270 Germanium
D7 = IN4003
K1 = 2 Form A or C Relay
(eg., Aromat TQ2E-5V)
L1 = VAC N4025-X034
R1 = 3k01 1%
D7
R2, 3 = 100Ω 1%
T1, 2 = Filtran TPW-3852-4
Figure 20 - ETS 300-012 NT & TE Line Interface for Filtran TPW-3852-4
9-98
MITEL [ MITEL NETWORKS CORPORATION ]
