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.
RO
RE
DE
DI
1
2
3
4
8
7
6
5
V
B
A
R
CC
Pin 5 – GND – Ground Connection.
Pin 6 – A – Driver Output/Receiver Input
Non-inverting.
D
GND
SP485
Pin 7 – B – Driver Output/Receiver Input Inverting.
Pin 8 – Vcc – Positive Supply +3.00V < VCC < +3.60V
Top View
SP3483
Pinout (Top View)
Receivers
DESCRIPTION
TheSP3483 receiver has 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 receiver of
the SP3483 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 SP3483 device is part of a family of +3.3V
lowpowerhalf-duplextransceiversthatmeetthe
specifications of the RS-485 and RS-422 serial
protocols. The device is pin-to-pin compatible
with the Sipex SP483 device as well as popular
industrystandards.TheSP3483featuresSipex's
BiCMOS process allowing low power operation
without sacrificing performance.
Drivers
The driver outputs of theSP3483 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 loading of 54Ω across the differential
outputs, the drivers maintain greater than 1.5V
voltage levels. The drivers 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
force the driver outputs into high impedance
(high-Z).
The receiver of the SP3483 will operate up to
250kbps. The receiver is equipped with a
fail-safe feature that guarantees the receiver
output will be in a HIGH state when the input
is left unconnected.
Shutdown Mode
TheSP3483 isequippedwithaShutdownmode.
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 SP3483 into Shutdown
mode. In Shutdown, supply current will drop to
typical 1µA, 10µA maximum.
The SP3483 has internally slew rate limited
driver outputs to minimize EMI. The tranceivers
will operate up to 250kbps. The 250mA ISC
maximum limit on the driver output allows the
SP3483 to withstand an infinite short circuit
over the -7.0V to +12.0V common mode range
without catastrophic damage to the IC.
Date: 6/23/04
SP3483 Low Power Slew Rate Limited Half-Duplex RS485 Transceivers
© Copyright 2004 Sipex Corporation
4
SIPEX [ SIPEX CORPORATION ]
