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SP3493 Datasheet, PDF (6/11 Pages) Sipex Corporation – +3.3V Low Power Slew Rate Limited RS-485/RS-422 Transceivers | |||
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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.
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 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
popular industry standards such as the MAX3486
and the 75176. The SP3494 has a partially slew-
rate limited driver with a data transmission rate
of 2.5Mbps.
Drivers
The SP3493/3494devices both have differential
outputs. The typical voltage output swing with
no load will bo 0V to V . With worst case
CC
loading of 54⦠across the differential outputs,
the driver can maintain greater than 1.5V voltage
levels.
The SP3494 device has an enable control line
which is active HIGH. A logic HIGH on DE (pin
3) will enable the differential driver outputs.
A logic LOW on DE (pin 3) will force the driver
outputs at high impedance (high-Z). The SP3493
device does not have a driver enable.
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
protection will allow the devices to withstand an
infinite short circuit over the -7.0V to +12V
common mode range without damage.
Receivers
The receivers have differential inputs with an
input sensitivity as low +200mV. Input
impedance of the receivers is typically 15kâ¦
(12k⦠minimum). A wide common mode range
of -7V to +12V allows for large ground potential
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 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.
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
on RE (pin 2) will put the SP3494 into shutdown.
In shutdown, the supply current will drop to 2nA
typical, 1µA maximum.
10/16/02
SP3493/3494 +3.3V Low Power Slew-Rate Limited RS-485/RS-422 Transceivers
6
© Copyright 2002 Sipex Corporation
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