SP3490 Datasheet, PDF (8/11 Pages) Sipex Corporation – +3.3V Low Power Full Duplex RS-485 Transceivers with 10Mbps Data Rate

DESCRIPTION
The SP3490 and the SP3491 are two members
in the family of +3.3V low power full duplex
transceivers that meet the electrical specifications
of the RS-485 and RS-422 serial protocols.
These devices are pin-to-pin compatible with
the Sipex SP490 and the SP491 devices as well
as popular industry standards. The SP3490 and
the SP3491 feature Sipex's BiCMOS process
allowing low power operation without sacrificing
performance.
Driver
The drivers for both the SP3490 and SP3491
have differential outputs. The typical voltage
output swing with no load will be 0 volts to V_CC.
With a load of 54Ω across the differential
outputs, the driver maintains greater than 1.5V
voltage levels.
The driver of the SP3491 has a driver enable
control line which is active high. A logic high on
DE (pin 4) of the SP3491 will enable the differ-
ential driver outputs. A logic low on DE (pin 4)
of the SP3491 will tri-state the driver outputs.
The SP3490 does not have a driver enable.
Receiver
The receivers for the SP3490 and SP3491 have
differential inputs with an input sensitivity
as low as ±100mV. Input impedance of the
receivers is typically 15kΩ (12kΩ minimum).
A wide common mode range of -7V to +12V
allows for large ground potential differences
between systems. The receivers for both the
SP3490 and SP3491 are equipped with a
fail-safe feature that guarantees the receiver
output will be in a high state when the input
is left unconnected.
The receiver of the SP3491 has a receiver enable
control line which is active low. A logic low on
REB (pin 3) of the SP3491 will enable the
differential receiver. A logic high on REB
(pin 3) of the SP3491 will tri-state the receiver.
Rev. 10/11/02
SP3490/3491 Low Power Full-Duplex RS485 Transceivers
8
© Copyright 2002 Sipex Corporation