The SP3493/SP3494 drivers will operate up to
250kbps and 2.5Mbps, respectively. In addition
to adhering to the 250mA ISC maximum limit on
the driver output, the driver output short-circuit
protectionwillallowthedevicestowithstandan
infinite short circuit over the -7.0V to +12V
common mode range without damage.
DESCRIPTION
The SP3493/3494 are +3.3V transceivers that
meet the electrical specifications of the
RS-485 and RS-422 serial protocols. The
SP3493/3494 feature Sipex's BiCMOS process
allowing low power operation without
sacrificing performance.
Receivers
The SP3493 device is a +3.3V full-duplex
transceiver that is pin-to-pin compatible with
the Sipex SP3490 and SP490 devices as well as
popular industry standards such as the
MAX3488, the LTC490, and the 75179. The
SP3493 has a driver with a data transmission
rate of 250kbps.
The receivers have differential inputs with an
input sensitivity as low +200mV. Input
impedance of the receivers is typically 15kΩ
(12kΩminimum). Awidecommonmoderange
of-7Vto+12Vallowsforlargegroundpotential
differences between systems.
Both the SP3493/SP3494 receivers are
equipped with fail-safe which guarantees that
the receiver outputs will be in a high state
when the input is left unconnected.
The SP3494 device is a +3.3V half-duplex
transceiver that is pin-to-pin compatible with
the Sipex SP3481 and SP481 devices as well as
popularindustrystandardssuchastheMAX3486
and the 75176. The SP3494 has a partially slew-
rate limited driver with a data transmission rate
of 2.5Mbps.
The SP3494 receiver has a high impedance
(high-Z) enable control pin. A logic LOW on
RE (pin 2) will enable the receiver; a logic
HIGH on RE (pin 2) will disable the receiver.
Drivers
The SP3494 is equipped with a shutdown mode.
To enable the shutdown state, both the driver
and receiver must be disabled simultaneously.
A logic LOW on DE (pin 3) and a logic HIGH
onRE(pin2)willputtheSP3494intoshutdown.
Inshutdown, thesupplycurrentwilldropto2nA
typical, 1µA maximum.
TheSP3493/3494devicesbothhavedifferential
outputs. The typical voltage output swing with
no load will bo 0V to V . With worst case
loading of 54Ω across theCdCifferential outputs,
thedrivercanmaintaingreaterthan1.5Vvoltage
levels.
The SP3494 device has an enable control line
whichisactiveHIGH. AlogicHIGHonDE(pin
3) will enable the differential driver outputs.
A logic LOW on DE (pin 3) will force the driver
outputsathighimpedance(high-Z). TheSP3493
device does not have a driver enable.
10/16/02
SP3493/3494 +3.3V Low Power Slew-Rate Limited RS-485/RS-422 Transceivers
© Copyright 2002 Sipex Corporation
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SIPEX [ SIPEX CORPORATION ]
