Datasheet

MAX3040–MAX3045
±10kV ESD-Protected, Quad 5V RS-485/RS-422
Transmitters
12 ______________________________________________________________________________________
Typical Multiple-Point Connection
Figure 14 shows a typical multiple-point connection for
the MAX3040–MAX3045 with the MAX3095. Because of
the high frequencies and the distances involved, high
attention must be paid to transmission-line effects while
using termination resistors. A terminating resistor (RT)
is simply a resistor that should be placed at the
extreme ends of the cable to match the characteristic
impedance of the cable. When the termination resis-
tance is not the same value as the characteristic
impedance of the cable, reflections will occur as the
signal is traveling down the cable. Although some
reflections are inevitable due to the cable and resistor
tolerances, large mismatches can cause significant
reflections resulting in errors in the data. With this in
mind, it is very important to match the terminating resis-
tance and the characteristic impedance as closely as
possible. As a general rule in a multi-drop system, termi-
nation resistors should always be placed at both ends of
the cable.
MAX3095MAX3043–MAX3045
RT
T1IN
T2IN
GND
V
CC
R1OUT
R1
D1
EN
EN
G
G
RT
R2OUT
R2
D2
T3IN
RT
R3OUT
R3
D3
T4IN
RT
R4OUT
R4
D4
GND
V
CC
Figure 13. Typical Connection of a Quad Transmitter and a Quad Receiver as a Pair