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DS1487 Datasheet

Low Power RS-485 1/4 Unit Load Multipoint Transceiver

No Preview Available !

January 1997
DS1487
Low Power RS-485 Unit Load Multipoint Transceiver
General Description
The DS1487 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 presents unit loading to the RS-485 bus al-
lowing up to 128 nodes to be connected together without
the use of repeaters
The transceiver draws 200 mA of supply current when un-
loaded or fully loaded with the driver disabled and operates
from a single a5V supply
The driver is short-circuit current limited and is protected
against excessive power dissipation by thermal shutdown
www.DataSheet4Uc.icrcouimtry 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
(VOD3)
The receiver has a failsafe feature that guarantees a logic-
high output if the input is open circuit
The DS1487 is available in surface mount and DIP pack-
ages
Features
Y Meets TIA EIA RS-485 multipoint standard
Y Allows up to 128 transceivers on the bus ( U L )
Y Guaranteed full load output voltage (VOD3)
Y Low quiescent current
200 mA typ
Y b7V to a12V common-mode input voltage range
Y TRI-STATE outputs on driver and receiver
Y AC performance
Driver transition time
Driver propagation delay
Driver skew
Receiver propagation delay
Receiver skew
25 ns typ
40 ns typ
1 ns typ
200 ns typ
20 ns typ
Y Half-duplex flow through pinout
Y Operates from a single 5V supply
Y Current-limiting and thermal shutdown for driver over-
load protection
Y Pin and functional compatible with MAX1487
Connection and Logic Diagram
Truth Table
Order Number
DS1487N
DS1487M
DIP and SOIC
Temp Range
0 C to a70 C
0 C to a70 C
TL F 12920 – 1
Package
DIP N08E
SOP M08A
DRIVER SECTION
RE DE DI
A
XHHH
XHL L
XLXZ
RECEIVER SECTION
RE DE
A-B
LL
LL
HX
LL
ta0 2V
sb0 2V
X
OPEN
Note Non Terminated Open Input only
X e indeterminate
Z e TRI-STATE
B
L
H
Z
RO
H
L
Z
H
TRI-STATE is a registered trademark of National Semiconductor Corporation
C1996 National Semiconductor Corporation TL F 12920
RRD-B30M17 Printed in U S A
http www national com


National Semiconductor Electronic Components Datasheet

DS1487 Datasheet

Low Power RS-485 1/4 Unit Load Multipoint Transceiver

No Preview Available !

Absolute Maximum Ratings (Note 1)
If Military Aerospace specified devices are required
please contact the National Semiconductor Sales
Office Distributors for availability and specifications
Supply Voltage (VCC)
Enable Input Voltage (RE DE)
Driver Input Voltage (DI)
Driver Output Voltage (A B)
a12V
b0 5V to (VCC a 0 5V)
b0 5V to (VCC a 0 5V)
b14V to a14V
Receiver Input Voltage (A B)
b14V to a14V
Receiver Output Voltage (RO)
b0 5V to (VCC a 0 5V)
Maximum Package Power Dissipation a25 C
M Package
1 19W
N Package
0 74W
Derate M Package 9 5 mW C above a25 C
Derate N Package 6 0 mW C above a25 C
Maximum Package Power Dissipation
M Package
N Package
Storage Temperature Range
Lead Temperature Range
(Soldering 4 sec )
ESD (HBM)
a70 C
0 76W
0 47W
b65 C to a150 C
a260 C
t2 kV
Recommended Operating
Conditions
Supply Voltage (VCC)
Operating Free Air
Temperature (TA)
DS1487
Min Typ Max Units
a4 75 a5 0 a5 25 V
0 a25 a70 C
Bus Common Mode Voltage b7
a12 V
Electrical Characteristics
Over Supply Voltage and Operating Temperature Ranges unless otherwise specified (Notes 2 3)
www.DataSheSyemt4boUl .com
Parameter
VOD1 Differential Driver Output Voltage
VOD2
Differential Driver Output Voltage
with Load
DVOD
Change in Magnitude of Output
Differential Voltage
Conditions
(No Load)
RL e 50X (RS422) Figure 1
RL e 27X (RS485) Figure 1
RL e 27X or 50X (Note 4)
Pin
AB
VOD3
VOC
DVOC
Differential Driver Output Voltage
Full Load with Max VCM
Driver Common-Mode Output Voltage
Change in Magnitude of Common-Mode
Output Voltage
R1 e 54X R2 e 375X
VTEST e b7V to a12V Figure 2
RL e 27X or 50X Figure 1
RL e 27X or 50X Figure 1 (Note 4)
VIH
VIL
IIN1
IIN2
VTH
DVTH
VOH
VOL
IOZR
RIN
ICC
IOSD1
IOSD2
IOSR
Input High Voltage
Input Low Voltage
Input Current
Input Current (Note 5)
DE e 0V VCC e 0V or 5 25V
Receiver Differential Threshold Voltage
Receiver Input Hysteresis
Receiver Output High Voltage
Receiver Output Low Voltage
TRI-STATE Output Current at Receiver
Receiver Input Resistance
No-Load Supply Current (Note 6)
Driver Short Circuit Current VO e HIGH
Driver Short Circuit Current VO e LOW
Receiver Short Circuit Current
VIN e 0V or VCC
VIN e a12V
VIN e b7V
b7V s VCM s a12V
VCM e 0V
IO e b4 mA VID e 0 2V
IO e 4 mA VID e b0 2V
0 4V s VO s 2 4V
b7V s VIN s a12V
DE e VCC RE e 0V or VCC
DE e 0V RE e 0V or VCC
b7V s VO s a12V
b7V s VO s a12V
VO e GND
DI DE
RE
AB
RO
AB
VCC
AB
RO
Min Typ Max Units
15 5 V
2 28
V
15 23
5
V
0 2 lVl
15 20
5
V
0 3V
0 2 lVl
20
08
g2
0 190 250
0 b100 b200
b0 2
02
70
35
05
g1
48 68
200 500
200 500
250
b250
7 85
V
V
mA
mA
mA
V
mV
V
V
mA
kX
mA
mA
mA
mA
mA
http www national com
2


Part Number DS1487
Description Low Power RS-485 1/4 Unit Load Multipoint Transceiver
Maker National Semiconductor
Total Page 8 Pages
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