STANDARD PRODUCT
PM4351 COMET
DATA SHEET
PMC-1970624
ISSUE 10
COMBINED E1/T1 TRANSCEIVER
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 1Ω (but can be up to about 2Ω) are optional, but if
not included then 1 to 2Ω 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 Description
Part #
Source
Rt1 & Rt2
Rterm
Typically 12.7Ω=±1% Resistors (see
Table 14)
18.2Ω=±1% Resistor for T1 & 120Ω
E1
13Ω=±1% Resistor for 75Ω= E1
(assuming a 1:2.42 transformer)
C0 & C1
4.7µF±10% Capacitors
PTC1 – PTC4
TC250-180
LC01-6
Raychem
Semtech
Semtech
1Ω Positive Temperature Coefficient
R
TVS1 & TVS2 6V Bi-directional Transient Voltage
Suppressor Diode
TVS2 & TVS3 6V Bi-directional Transient Voltage
Suppressor Diode
LC03-6
D1
Surge Protector Diode Array
SRDA3.3-4
SGT27B13
Semtech
Harris
Z1 – Z4
Bi-directional Transient Surge
Suppressors
T1 & T2
Generally 1:2.42CT Transformers
(see Table 14)
50436 (single) Midcom
T1137 (dual)
TG23-1505NS
(single)
Pulse
Halo
TG23-1505N1
(dual)
Halo
PROPRIETARY AND CONFIDENTIAL
34
PMC [ PMC-SIERRA, INC ]
