STANDARD PRODUCT
PM4351 COMET
DATA SHEET
PMC-1970624
ISSUE 10
COMBINED E1/T1 TRANSCEIVER
PROPRIETARY AND CONFIDENTIAL
34
1) for systems requiring phantom feed or inter-building line protection
2) for systems with no DC current requirements or intra-building line protection.
See Table 12 for the descriptions of components for Figure 5. See Table 14 for
the descriptions of values for the transformer turns ratio, n, Rt1 and Rt2 for
Figure 5.
Figure 5 assumes primary protectors (like carbon blocks) are also present. The
protection resistors (PTCs) of 1
(but can be up to about 2
) are optional, but if
not included then 1 to 2
resistor with a series fuse should be used instead.
Note that the crowbar devices (Z1 – Z4) are not required if the transformer’s
isolation rating is not exceeded.
Table 12
- External Component Descriptions
Component
Rt1 & Rt2
Description
Part #
Source
Typically 12.7
=
±
1% Resistors (see
Table 14)
Rterm
18.2
=
±
1% Resistor for T1 & 120
E1
13
=
±
1% Resistor for 75
=
E1
(assuming a 1:2.42 transformer)
C0 & C1
4.7
μ
F
±
10% Capacitors
PTC1 – PTC4 1
Positive Temperature Coefficient
R
TVS1 & TVS2 6V Bi-directional Transient Voltage
Suppressor Diode
TVS2 & TVS3 6V Bi-directional Transient Voltage
Suppressor Diode
D1
Surge Protector Diode Array
Z1 – Z4
Bi-directional Transient Surge
Suppressors
T1 & T2
Generally 1:2.42CT Transformers
(see Table 14)
TC250-180
Raychem
LC01-6
Semtech
LC03-6
Semtech
SRDA3.3-4
SGT27B13
Semtech
Harris
50436 (single)
T1137 (dual)
TG23-1505NS
(single)
TG23-1505N1
(dual)
Midcom
Pulse
Halo
Halo