Datasheet

In a switching-card architecture, a common switching
card contains all the protection switches for the T1/E1/J1
lines entering the system (see Figures 7 and 8).
With an adjacent card architecture, the switches pro-
tecting any given line card reside physically in the adja-
cent line card (see Figures 9 and 10).
Receive and transmit interfaces reside in the same
board for each T1/E1/J1 port. The diagrams represent
the typical interface transformers and resistors recom-
mended for Dallas/Maxim LIUs, such as the DS21Q55.
The protection switches are placed in the low-voltage
side of the transformer to meet the isolation require-
ments. Note that there is also a TVS in the line side of
the transformers. The receive and transmit resistors pro-
vide impedance matching to the T1/E1/J1 transmission
cable characteristic impedance. Refer to Application
Note 2857 for more information on T1/E1/J1 applications.
MAX4670
Integrated T1/E1/J1 Short-Haul and
Long-Haul Protection Switch
_______________________________________________________________________________________ 9
MAX4670
NO1
R
X
NC1
COM1
NO2
R
X
NC2
COM2
INA
INB
INC
IND
NO3
T
X
NC3
COM3
NO4
T
X
NC4
COM4
NO5
T
X
NC5
COM5
NO6
T
X
NC6
COM6
NO7
R
X
NC7
COM7
NO8
R
X
NC8
COM8
0.6
Ω
0.6
Ω
0.6
Ω
0.6
Ω
0.6
Ω
0.6
Ω
0.6
Ω
0.6
Ω
V+
GND SWITCH
INA NC1/NC2 NO1/NO2
LOW X OFF ON
HIGH LOW OFF ON
HIGH HIGH ON OFF
INB NC3/NC4 NO3/NO4
LOW X OFF ON
HIGH LOW OFF ON
HIGH HIGH ON OFF
INC NC5/NC6 NO5/NO6
LOW X OFF ON
HIGH LOW OFF ON
HIGH HIGH ON OFF
IND NC7/NC8 NO7/NO8
LOW X OFF ON
HIGH LOW OFF ON
HIGH HIGH ON OFF
SWITCH
Figure 1. Functional Diagram