DS481 Low Power RS-485/RS-422 Multipoint Transceiver with Sleep Mode
July 1998
DS481
Low Power RS-485/RS-422 Multipoint Transceiver with
Sleep Mode
General Description
The DS481 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
2.0 Mbps (see Applications Information section).
The transceiver draws 200 碌A(chǔ) of supply current when un-
loaded or 0.2 碌A(chǔ) when in the automatic sleep mode. Sleep
mode is activated by inactivity on the enables (DE and RE
(Note 1)). Holding DE = L and RE (Note 1) = H for greater than
600 ns will enable the sleep mode. The DS481 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
廬
(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 DS481 is available in surface mount and DIP packages
and is characterized for Industrial and Commercial tempera-
ture range operation.
Features
n
n
n
n
n
n
n
Meets TIA/EIA RS-485 multipoint standard
Sleep mode reduces I
CC
to 0.2 碌A(chǔ)
Guaranteed full load output voltage (V
OD3
)
Low quiescent current: 200 碌A(chǔ) typ
鈭?V to +12V common-mode input voltage range
TRI-STATE outputs on driver and receiver
AC performance:
鈥?Driver transition time: 25 ns typ
鈥?Driver propagation delay: 40 ns typ
鈥?Driver skew: 1 ns typ
鈥?Receiver propagation delay: 200 ns typ
鈥?Receiver skew: 20 ns typ
Half-duplex flow through pinout
Operates from a single 5V supply
Allows up to 128 transceivers on the bus (DS481N/M)
Allows up to 64 tranceivers on the bus (DS481TN/M)
Current-limiting and thermal shutdown for driver
overload protection
Industrial temperature range operation
Pin and functional compatible with MAX481C and
MAX481E
n
n
n
n
n
n
n
Connection and Logic Diagram
Truth Table
DRIVER SECTION
RE
(Note 1)
X
X
X
DE
H
H
L
DE
L
L
X
L
DI
H
L
X
A-B
鈮?0.2V
鈮も垝0.2V
X
OPEN (Note 1)
A
H
L
Z
B
L
H
Z (Note 2)
RO
H
L
Z (Note 2)
H
RECEIVER SECTION
DS012919-1
*Note: Non Terminated, Open Input only
RE
(Note 1)
L
L
H
L
X = indeterminate
Z = TRI-STATE
Order Number
DS481N
DS481M
DS481TN
DS481TM
Temp. Range
0藲C to +70藲C
0藲C to +70藲C
鈭?0藲C to +85藲C
鈭?0藲C to +85藲C
Package/###
DIP/N08E
SOP/M08A
DIP/N08E
SOP/M08A
Note 1:
Non Terminated, Open Input only
Note 2:
Device enters sleep mode if enable conditions are held
>
600 ns,
DE = L and RE (Note 1) = H.
TRI-STATE
廬
is a registered trademark of National Semiconductor Corporation.
漏 1999 National Semiconductor Corporation
DS012919
www.national.com
1
2
3
4
5
6
7
8
9
10
