SP26LV431 Datasheet, PDF (9/22 Pages) Sipex Corporation – High Speed, +3.3V Quad RS-422 Differential Line Driver

SP26LV431
REV. 1.1.0
HIGH SPEED +3.3V QUAD RS-422 DIFFERENTIAL LINE DRIVER
1.0 PRODUCT DESCRIPTION
The SP26LV431 is a low-power quad differential line driver designed for digital data transmission meeting the
specifications of the EIA standard RS-422 serial protocol. The SP26LV431 features Exar's BiCMOS process
allowing low power operational characteristics of CMOS technology 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 communication. 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 common
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 Table 1. 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 Table 1.
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.
FIGURE 9. TWO-WIRE BALANCED SYSTEM, RS-422
TABLE 1: TRUTH TABLE, ENABLE/DISABLE FUNCTION COMMON TO ALL FOUR RS-422 DRIVERS
ENABLE
ENABLE
INPUT
NON-INVERTING A
OUTPUT
INVERTING B OUTPUT
LOW
HIGH
don’t care
high-Z
high-Z
HIGH
don’t care
LOW
LOW
HIGH
don’t care
LOW
HIGH
HIGH
LOW
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