SP3481 Datasheet, PDF (4/9 Pages) Sipex Corporation – +3.3V Low Power Half-Duplex RS-485 Transceivers with 10Mbps Data Rate

RO 1
RE 2
DE 3
DI 4
R
8 V_CC
7B
6A
D
SP485 ^{5 GND}
Top View
SP3481/SP3485
Pinout (Top View)
DESCRIPTION
The SP3481 and the SP3485 are 2 members
in the family of +3.3V low power half-duplex
transceivers that meet the specifications of the
RS-485 and RS-422 serial protocols. These
devices are pin-to-pin compatible with the Sipex
SP481, SP483, and SP485 devices as well as
popular industry standards. The SP3481 and
the SP3485 feature Sipex's BiCMOS process
allowing low power operation without sacrificing
performance.
Drivers
The driver outputs of the SP3481 and SP3485
are differential outputs meeting the RS-485 and
RS-422 standards. The typical voltage output
swing with no load will be 0 Volts to +3.3 Volts.
With a load of 54Ω across the differential
outputs, the drivers maintain greater than
1.5V voltage levels. The drivers of the SP3481
and SP3485 have 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 tri-state the
driver outputs.
The tranceivers in the SP3481 and SP3485
operate up to 10Mbps. The 250mA I_SC
maximum limit on the driver output allows
the SP3481 and the SP3485 to withstand an
infinite short circuit over the -7.0V to +12.0V
common mode range without catastrophic
damage to the IC.
PIN FUNCTION
Pin 1 – RO – Receiver Output.
Pin 2 – RE – Receiver Output Enable Active LOW.
Pin 3 – DE – Driver Output Enable Active HIGH.
Pin 4 – DI – Driver Input.
Pin 5 – GND – Ground Connection.
Pin 6 – A – Driver Output/Receiver Input
Non-inverting.
Pin 7 – B – Driver Output/Receiver Input Inverting.
Pin 8 – V_CC
Receivers
The SP3481 and SP3485 receivers have
differential inputs with an input sensitivity as
low as ±200mV. 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 of the SP3481
and SP3485 have a tri-state 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 receivers of the SP3481 and SP3485 operate
up to 10Mbps. The receiver for each of the three
devices is equipped with fail-safe. Fail-safe
guarantees that the receiver output will be in a
HIGH state when the input is left unconnected.
Shutdown Mode for the SP3481
The SP3481 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 SP3481 into Shutdown
mode. In Shutdown, supply current will drop to
typical 1µA, 10µA maximum.
10/15/02
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
4
© Copyright 2000 Sipex Corporation