SP4082E Datasheet, PDF (12/14 Pages) Exar Corporation – 5V RS-485/RS-422 Transceivers 1/8th Unit Load, Slew-Rate Limited, ±15kV ESD-Protected

tion against short circuits over the whole com-
mon-mode voltage range. Second, a thermal-
shutdown circuit forces the driver outputs into
a high-impedance state if junction temperature
becomes excessive.
LINE LENGTH, EMI, AND REFLECTIONS
It features controlled slew-rate drivers that mini-
mize EMI and reduce reflections caused by im-
properly terminated cables.
Driver rise and fall times are limited to no faster
than 667ns, allowing error-free data transmis-
sion up to 115kbps.
The RS-485/RS-422 standard covers line
lengths up to 4,000ft. Maximum achievable
line length is a function of signal attenuation
and noise. Use of slew-controlled drivers may
help to reduce crosstalk interference and permit
communication over longer transmission lines.
Termination prevents reflections by eliminating
the impedance mismatches on a transmission
line. Line termination is typically used if rise and
fall times are shorter than the round-trip signal
propagation time. Slew-limited drivers may re-
duce or eliminate the need for cable termination
in many applications.
Typical ApplicationS:
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DESCRIPTION
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)6687000 • Fax [phone] • www.exar.com
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