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DS36C278
Low Power Multipoint EIA-RS-485 Transceiver
General Description
The DS36C278 is a low power differential bus line trans-
ceiver designed to meet the requirements of RS-485 stan-
dard for multipoint data transmission In addition it is com-
patible with TIA EIA-422-B
The CMOS design offers significant power savings over its
bipolar and ALS counterparts without sacrificing ruggedness
against ESD damage The device is ideal for use in battery
powered or power conscious applications I
500 A maximum
The driver and receiver outputs feature TRI-STATE capa-
bility The driver outputs operate over the entire common
mode range of
7V to
12V Bus contention or fault situa-
b
a
tions that cause excessive power dissipation within the de-
vice are handled by a thermal shutdown circuit which forces
the driver outputs into the high impedance state
The receiver incorporates a fail safe circuit which guaran-
tees a high output state when the inputs are left open
The DS36C278T is fully specified over the industrial temper-
ature range (
40 C to
85 C)
b
a
Connection and Logic Diagram
Order Number DS36C278TM DS36C278TN
DS36C278M DS36C278N
See NS Package Number M08A or N08E
TRI-STATE is a registered trademark of National Semiconductor Corporation
C 1996 National Semiconductor Corporation
is specified at
CC
TL F 12040– 1
TL F 12040
Features
100% RS-485 compliant
Y
Guaranteed RS-485 device interoperation
Low power CMOS design
Y
Built-in power up down glitch-free circuitry
Y
Permits live transceiver insertion displacement
DIP and SOIC packages available
Y
Industrial temperature range
Y
On-board thermal shutdown circuitry
Y
Prevents damage to the device in the event of ex-
cessive power dissipation
Wide common mode range
Y
Receiver open input fail-safe
Y
unit load (DS36C278)
Y
unit load (DS36C278T)
Y
ESD (human body model)
Y
Drop in replacement for
Y
LTC485 MAX485 DS75176 DS3695
Truth Table
DRIVER SECTION
RE
DE
DI
X
H
H
X
H
L
X
L
X
RECEIVER SECTION
RE
DE
RI-RI
L
L
t
a
L
L
s
b
H
L
L
L
OPEN
Note Non-terminated open input only
RRD-B30M36 Printed in U S A
December 1995
I
500 A max
CC
40 C to
85 C
b
a
7V to
12V
b
a
128 nodes
t
64 nodes
t
2 kV
t
DO RI
DO RI
H
L
L
H
Z
Z
RO
0 2V
H
0 2V
L
X
Z
H
http
www national com
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Table of Contents
Summary of Contents for National Semiconductor DS36C278
-
Page 1: General Description
0 2V DS36C278M DS36C278N See NS Package Number M08A or N08E OPEN Note Non-terminated open input only TRI-STATE is a registered trademark of National Semiconductor Corporation C 1996 National Semiconductor Corporation http www national com TL F 12040 RRD-B30M36 Printed in U S A... -
Page 2: Absolute Maximum Ratings
Absolute Maximum Ratings Recommended Operating (Note 1) Conditions If Military Aerospace specified devices are required please contact the National Semiconductor Sales Units Office Distributors for availability and specifications Supply Voltage (V 4 75 5 25 Supply Voltage (V Bus Voltage... -
Page 3: Device Characteristics
Disable Time High to Z 15 pF Figures 7 8 Disable Time Low to Z Figures 9 10 Enable Time Z to High 100 pF Figures 7 8 Enable Time Z to Low Figures 9 10 http www national com... -
Page 4: Parameter Measurement Information
V TL F 12040 – 4 TL F 12040–3 Vtest 7V to FIGURE 3 Driver V and V FIGURE 4 Driver I TL F 12040 – 5 FIGURE 5 Driver Differential Propagation Delay Test Circuit http www national com... - Page 5 FIGURE 10 TRI-STATE Waveforms (t TL F 12040 – 9 FIGURE 9 TRI-STATE Test Circuit (t TL F 12040 – 12 FIGURE 12 Receiver Differential Propagation Delay TL F 12040– 11 Test Circuit FIGURE 11 Receiver V and V http www national com...
- Page 6 TL F 12040 – 14 FIGURE 14 Receiver TRI-STATE Test Circuit TL F 12040 – 15 FIGURE 15 Receiver Enable and Disable Waveforms (t TL F 12040 – 16 FIGURE 16 Receiver Enable and Disable Waveforms (t http www national com...
- Page 7 Figure 18 are TL F 12040 – 19 scaled also Again both 0 mA reference points at 5V and FIGURE 18 Input Current vs Input Voltage 3V stay the same The other reference points are Operating Range http www national com...
- Page 8 com...
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Page 9: Physical Dimensions
Physical Dimensions inches (millimeters) 8-Lead (0 150 Wide) Molded Small Outline Package JEDEC Order Number DS36C278TM DS36C278M NS Package Number M08A http www national com... -
Page 10: Life Support Policy
49 (0) 180-534 16 80 Fax (852) 2736-9960 National does not assume any responsibility for use of any circuitry described no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications...