July 1998
DS36277
Dominant Mode Multipoint Transceiver
General Description
Features
n FAILSAFE receiver, RO = HIGH for:
— OPEN inputs
The DS36277 Dominant Mode Multipoint Transceiver is de-
signed for use on bi-directional differential busses. It is opti-
mal for use on Interfaces that utilize Society of Automotive
Engineers (SAE) J1708 Electrical Standard.
— Terminated inputs
— SHORTED inputs
n Optimal for use in SAE J1708 Interfaces
n Compatible with popular interface standards:
— TIA/EIA-485 and TIA/EIA-422-A
— CCITT recommendation V.11
n Bi-directional transceiver
— Designed for multipoint transmission
n Wide bus common mode range
— (−7V to +12V)
The device is similar to standard TIA/EIA-485 transceivers,
but differs in enabling scheme. The Driver’s Input is normally
externally tied LOW, thus providing only two states: Active
(LOW), or Disabled (OFF). When the driver is active, the
dominant mode is LOW, conversely, when the driver is dis-
abled, the bus is pulled HIGH by external bias resistors.
The receiver provides a FAILSAFE feature that guarantees a
known output state when the Interface is in the following con-
ditions: Floating Line, Idle Line (no active drivers), and Line
Fault Conditions (open or short). The receiver output is
HIGH for the following conditions: Open Inputs, Terminated
Inputs (50Ω), or Shorted Inputs. FAILSAFE is a highly desir-
able feature when the transceivers are used with Asynchro-
nous Controllers such as UARTs.
n Available in plastic DIP and SOIC packages
Connection and Logic Diagram
Truth Tables
Driver
Inputs
Outputs
DE
L
DI
L
DO/RI
DO /RI
L
H
Z
H
L
L
H
X
H
Z
DS011384-1
Order Number DS36277TM or DS36277TN
See NS Package Number M08A or N08E
Receiver
Inputs
Output
RE
L
DO/RI–DO /RI
RO
H
≥ 0 mV
≤ −500 mV
SHORTED
OPEN
L
L
L
H
L
H
H
X
Z
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© 1999 National Semiconductor Corporation
DS011384
www.national.com
NSC [ National Semiconductor ]
