DS485 Datasheet, PDF (1/10 Pages) National Semiconductor (TI) – Low Power RS-485/RS-422 Multipoint Transceiver

July 1998
DS485
Low Power RS-485/RS-422 Multipoint Transceiver
General Description
The DS485 is a low-power transceiver for RS-485 and
RS-422 communication. The device contains one driver and
one receiver. The drivers slew rate allows for operation up to
2.5 Mbps (see Applications Information section).
The transceiver draws 200 µA of supply current when un-
loaded or fully loaded with the driver disabled and operates
from a single +5V supply.
The driver is short-circuit current limited and is protected
against excessive power dissipation by thermal shutdown
circuitry that places the driver outputs into TRI-STATE^®
(High Impedance state) under fault conditions. The driver
guarantees a minimum of 1.5V differential output voltage
with maximum loading across the common mode range
(V_OD3).
The receiver has a failsafe feature that guarantees a
logic-high output if the input is open circuit.
The DS485 is available in surface mount and DIP packages
and is characterized for Industrial and Commercial tempera-
ture range operation.
Features
n Meets TIA/EIA RS-485 multipoint standard
n Guaranteed full load output voltage (V _OD3)
n Low quiescent current: 200 µA typ
n −7V to +12V common-mode input voltage range
n TRI-STATE outputs on driver and receiver
n AC performance:
— Driver transition time: 25 ns typ
— Driver propagation delay: 40 ns typ
— Driver skew: 1 ns typ
— Receiver propagation delay: 200 ns typ
— Receiver skew: 20 ns typ
n Half-duplex flow through pinout
n Operates from a single 5V supply
n Allows up to 32 transceivers on the bus
n Current-limiting and thermal shutdown for driver
overload protection
n Industrial temperature range operation
n Pin and functional compatible with MAX485 and LTC485
Connection and Logic Diagram
Truth Table
DIP and SOIC
DRIVER SECTION
RE*
DE
DI
A
B
X
H
H
H
L
X
H
L
L
H
X
L
X
Z
Z
RECEIVER SECTION
RE*
DE
A-B
RO
L
L
≥+0.2V
H
DS012880-1
L
L
≤−0.2V
L
H
X
X
Z
Order Number
Temp. Range
Package/###
L
L
OPEN*
H
DS485N
0˚C to +70˚C
DIP/N08E
DS485M
0˚C to +70˚C
SOP/M08A
*Note: Non Terminated, Open Input only
X = indeterminate
DS485TN
−40˚C to +85˚C
DIP/N08E
Z = TRI-STATE
DS485TM
−40˚C to +85˚C
SOP/M08A
TRI-STATE^® is a registered trademark of National Semiconductor Corporation.
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