SP26LV431 Datasheet, PDF (5/13 Pages) Sipex Corporation – High Speed, +3.3V Quad RS-422 Differential Line Driver

The SP26LV431 is a low-power quad differen-
tial line driver designed for digital data transmis-
sion meeting the specifications of the EIA stan-
dard RS-422 serial protocol. The SP26LV431
features Sipex's BiCMOS process allowing low
power operational characteristics of CMOS tech-
nology while meeting all of the demands of the
RS-422 serial protocol up to 60Mbps under load
in harsh environments.
The RS-422 standard is ideal for multi-drop
applications and for long-distance communica-
tion. The RS-422 protocol allows up to 10
receivers to be connected to a data bus, making
it an ideal choice for multi-drop applications.
Since the cabling can be as long as 4,000 feet,
RS-422 drivers are equipped with a wide com-
mon mode output range to accommodate ground
potential differences. Because the RS-422 is a
differential interface, data is virtually immune to
noise in the transmission line.
The SP26LV431 accepts TTL or CMOS input
levels and translates these to RS-422 output
levels. The SP26LV431 features active HIGH
and active LOW driver enable controls common
to all four driver channels see Figure 8. A logic
HIGH on the ENABLE pin (pin 4) or a logic
LOW on the ENABLE pin (pin 12) will enable the
differential driver outputs. A logic LOW on the
ENABLE pin (pin 4) and a logic HIGH on the
ENABLE pin (pin 12) will force the driver
outputs into high impedance (high-Z). Refer to
the truth table in Figure 8.
THEORY OF OPERATION
source and sink current capability. All drivers
are internally protected against short circuits on
their outputs. The driver outputs are short-circuit
limited to 150mA. The driver output skew times
are typically 0.8ns.
To minimize reflections, the multipoint bus
transmission line should be terminated at both
ends in its characteristic impedance, and stub
lengths off the main line should be kept as short
as possible.
ENABLE
DATA
ENABLE
*RT
DATA
OUTPUT
*RT is optional although highly
recommended to reduce reflection.
The RS-422 line driver outputs feature high
Figure 7. Two-Wire Balanced System, RS-422
ENABLE
LOW
ENABLE
Input
Non-
Inverting
A Output
Inverting
B Output
HIGH don't care high-Z
high-Z
HIGH don't care
LOW
LOW
HIGH
don't care
LOW
HIGH
HIGH
LOW
Figure 8. Truth Table, Enable / Disable Function
Common to All Four RS-422 Drivers
Rev: A Date: 2/08/04
SP26LV431 High Speed, +3.3V Quad RS-422 Differential Line Driver
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© Copyright 2004 Sipex Corporationn