Datasheet

MAX3172/MAX3174
+3.3V Multiprotocol Software-Selectable
Cable Terminators and Transceivers
12 ______________________________________________________________________________________
with a minimum of a 100Ω resistor (Figure 6). This resis-
tor, although not required, prevents reflections from
corrupting transmitted data.
In Figure 7, the MAX3172/MAX3174 are used to termi-
nate the V.11 receiver. Internal to the MAX3172/
MAX3174, S1 is closed and S2 is open to present a
104Ω typical differential resistance and high-Z com-
mon-mode impedance. S3 opens to disable the
MAX3170’s internal V.28 termination.
The V.11 specification allows for signals with common-
mode variations of ±7V with differential signal ampli-
tudes from 2V to 6V. Also, data rates may be as high as
10Mbps. The MAX3172/MAX3174 maintain steady ter-
mination impedance between 100Ω and 110Ω over
these conditions.
V.35 Termination
Figure 8 shows a standard V.35 interface. The genera-
tor and the load must both present a 100Ω ±1 0 Ω differ-
ential impedance and a 150Ω ±1 5Ω common-mode
impedance (as shown by the resistive T-networks in
Figure 8). The V.35 driver generates a current output
(typically ±11mA) that develops an output voltage
between 440mV and 660mV across the load termina-
tion networks.
R6
10kΩ
R8
5kΩ
R3
127Ω
R2
52Ω
R1
52Ω
A′
B′
C′
A
B
GND
R5
30kΩ
R7
10kΩ
R4
30kΩ
MAX3172
MAX3174
MAX3170
S3
S2
S1
RECEIVER
50Ω
50Ω
125Ω
50Ω
50Ω
125Ω
A′
B′
C′
A
B
C
GENERATOR
BALANCED
INTERCONNECTING
CABLE
CABLE
TERMINATION
RECEIVER
LOAD
Figure 8. Typical V.35 Interface
Figure 7. V.11 Termination and Internal Resistance Networks