DS485
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SNLS122C – JULY 1998 – REVISED APRIL 2013
DS485 Low Power RS-485/RS-422 Multipoint Transceiver
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FEATURES
DESCRIPTION
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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).
1
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Meets TIA/EIA RS-485 Multipoint Standard
ensured Full Load Output Voltage (V OD3)
Low Quiescent Current: 200 μA typ
−7V to +12V Common-Mode Input Voltage
Range
TRI-STATE Outputs on Driver and Receiver
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
Half-Duplex Flow Through Pinout
Operates From a Single 5V Supply
Allows Up To 32 Transceivers on the Bus
Current-Limiting and Thermal Shutdown For
Driver Overload Protection
Industrial Temperature Range Operation
Pin and Functional Compatible With MAX485
and LTC485
The transceiver draws 200 μA of supply current when
unloaded 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 ensures a minimum
of 1.5V differential output voltage with maximum
loading across the common mode range (VOD3).
The receiver has a failsafe feature that ensures a
logic-high output if the input is open circuit.
The DS485 is available in 8-pin SOIC and PDIP
packages and is characterized for Industrial and
Commercial temperature range operation.
TRUTH TABLE
Connection and Logic Diagram
DRIVER SECTION
RE*
DE
DI
A
B
X
H
H
H
L
X
H
L
L
H
X
L
X
Z
Z
RECEIVER SECTION
Figure 1. 8-Pin SOIC or PDIP
See D or P Package
(1)
RE*
DE
A-B
RO
L
L
≥+0.2V
H
L
L
≤−0.2V
L
H
X
X
Z
L
L
OPEN* (1)
H
Non Terminated, Open Input only
X = indeterminate
Z = TRI-STATE
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 1998–2013, Texas Instruments Incorporated
DS485
SNLS122C – JULY 1998 – REVISED APRIL 2013
www.ti.com
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
ABSOLUTE MAXIMUM RATINGS (1) (2)
Supply Voltage (VCC)
+12V
Enable Input Voltage (RE*, DE)
−0.5V to (VCC + 0.5V)
Driver Input Voltage (DI)
−0.5V to (VCC + 0.5V)
−14V to +14V
Driver Output Voltage (A, B)
−14V to +14V
Receiver Input Voltage (A, B)
−0.5V to (VCC + 0.5V)
Receiver Output Voltage (RO)
Maximum Package Power Dissipation @ +25°C
SOIC Package
1.19W
PDIP Package
0.74W
SOIC Package
0.76W
Derate SOIC Package 9.5 mW/°C above +25°C
Derate PDIP Package 6.0 mW/°C above +25°C
Maximum Package Power Dissipation @ +70°C
PDIP Package
0.47W
−65°C to +150°C
Storage Temperature Range
Lead Temperature Range
Soldering, 4 sec
+260°C
≥2 kV
ESD (HBM)
(1)
(2)
If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and
specifications.
Absolute Maximum Ratings are those values beyond which the safety of the device cannot be ensured. They are not meant to imply that
the devices should be operated at these limits. The table of ELECTRICAL CHARACTERISTICS specifies conditions of device operation.
RECOMMENDED OPERATING CONDITIONS
Supply Voltage (VCC)
Operating Free Air Temperature (TA)
DS485
DS485T
Typ
Max
Units
+5.0
+5.25
V
0
+25
+70
°C
−40
+25
+85
°C
+12
V
−7
Bus Common Mode Voltage
2
Min
+4.75
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SNLS122C – JULY 1998 – REVISED APRIL 2013
ELECTRICAL CHARACTERISTICS
Over Supply Voltage and Operating Temperature Ranges, unless otherwise specified (1) (2)
Symbol
Parameter
Conditions
Pin
Min
Typ
Units
5
V
VOD1
Differential Driver Output Voltage
(No Load)
VOD2
Differential Driver Output Voltage
with Load
RL = 50Ω, (RS422), See Figure 2
2
2.8
RL = 27Ω, (RS485), See Figure 2
1.5
2.3
ΔVOD
Change in Magnitude of Output
Differential Voltage
RL = 27Ω or 50Ω (3)
VOD3
Differential Driver Output Voltage—
Full Load with Max VCM
R1 = 54Ω, R2 = 375Ω
VTEST = −7V to +12V, See Figure 6
VOC
Driver Common-Mode Output Voltage
RL = 27Ω or 50Ω, See Figure 2
ΔVOC
Change in Magnitude of Common-Mode
Output Voltage
RL = 27Ω or 50Ω, See Figure 2 (3)
VIH
Input High Voltage
VIL
Input Low Voltage
IIN1
Input Current
VIN = 0V or VCC
IIN2
Input Current (4)
DE = 0V, VCC = 0V or 5.25V
VIN = +12V
VTH
Receiver Differential Threshold Voltage
−7V ≤ VCM ≤ +12V
ΔVTH
Receiver Input Hysteresis
VCM = 0V
VOH
Receiver Output High Voltage
IO = −4 mA, VID = 0.2V
VOL
Receiver Output Low Voltage
IO = 4 mA, VID = −0.2V
0.4
V
IOZR
TRI-STATE Output Current at Receiver
0.4V ≤ VO ≤ 2.4V
±1
μA
RIN
Receiver Input Resistance
−7V ≤ VIN ≤ +12V
A, B
ICC
(5)
DE = VCC, RE* = 0V or VCC
VCC
No-Load Supply Current
A, B
Max
1.5
DI,
DE,
RE*
Driver Short Circuit Current, VO = HIGH
−7V ≤ VO ≤ +12V
IOSD2
Driver Short Circuit Current, VO = LOW
−7V ≤ VO ≤ +12V
IOSR
Receiver Short Circuit Current
0V ≤ VO ≤ VCC
(2)
(3)
(4)
(5)
0.2
|V|
5
V
3
V
0.2
|V|
V
A, B
VIN = −7V
IOSD1
V
2.0
−0.2
0.8
V
±2
μA
1.0
mA
−0.8
mA
0.2
70
RO
A, B
RO
V
mV
3.5
V
12
kΩ
μA
200
900
200
500
μA
35
250
mA
35
250
mA
7
85
mA
DE = 0V, RE* = 0V or VCC
(1)
2.0
V
5
Current into device pins is defined as positive. Current out of device pins is defined as negative. All voltages are referenced to ground
except VOD1/2/3 and VID.
All typicals are given for: VCC = +5.0V, TA = +25°C.
Δ|VOD| and Δ|VOC| are changes in magnitude of V OD and VOC respectively, that occur when the input changes state.
IIN2 includes the receiver input current and driver TRI-STATE leakage current.
Supply current specification is valid for loaded transmitters when DE = 0V or enabled (DE = H) with no load.
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DS485
SNLS122C – JULY 1998 – REVISED APRIL 2013
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SWITCHING CHARACTERISTICS
Over Supply Voltage and Operating Temperature Ranges, unless otherwise specified (1) (2) (3)
Symbol
Parameter
Conditions
RL = 54Ω, CL = 100 pF
Min
Typ
Max
Units
10
40
65
ns
10
39
65
ns
1
10
ns
3
25
40
ns
3
25
tPLHD
Driver Differential Propagation Delay—Low to High
tPHLD
Driver Differential Propagation Delay—High to Low
tSKEW
Differential Skew |tPHLD − tPLHD|
tr
Driver Rise Time
tf
Driver Fall Time
40
ns
tZH
Driver Enable to Output High
CL = 100 pF
170
ns
tZL
Driver Enable to Output Low
CL = 100 pF
170
ns
tLZ
Driver Disable from Output Low
CL = 15 pF
170
ns
tHZ
Driver Disable from Output High
CL = 15 pF
170
ns
tPLHD
Receiver Differential Propagation Delay—Low to High
CL = 15 pF (RO)
tPHLD
Receiver Differential Propagation Delay—High to Low
tSKEW
Differential Skew |tPHLD − tPLHD|
tZH
Receiver Enable to Output High
tZL
70
190
320
ns
70
210
320
ns
20
50
ns
110
ns
Receiver Enable to Output Low
110
ns
tLZ
Receiver Disable from Output Low
110
ns
tHZ
Receiver Disable from Output High
110
fmax
Maximum Data Rate
(1)
(2)
(3)
(4)
4
CL = 15 pF
See
(4)
2.5
ns
Mbps
All typicals are given for: VCC = +5.0V, TA = +25°C.
f = 1 MHz, tr and tf ≤ 6 ns, ZO = 50Ω.
CL includes jig and probe capacitance.
fmax is the ensured data rate for 50 ft of twisted pair cable. f max may be conservatively determined from the ratio of driver transition time
(tr) to the data rate unit interval (1/fmax). Using a 10% ratio yields fmax = (0.1)/40 ns = 2.5 Mb/s. Higher data rates may be supported by
allowing larger ratios.
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SNLS122C – JULY 1998 – REVISED APRIL 2013
PARAMETER MEASUREMENT INFORMATION
Figure 2. VOD
Figure 3.
Figure 4.
Figure 5.
Figure 6. VOD3
Figure 7.
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DS485
SNLS122C – JULY 1998 – REVISED APRIL 2013
www.ti.com
Figure 8.
Figure 9.
Figure 10.
Figure 11.
Figure 12.
Figure 13.
6
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SNLS122C – JULY 1998 – REVISED APRIL 2013
Figure 14.
PIN DESCRIPTIONS
Pin #
I/O
Name
1
O
RO
Receiver Output: If A > B by 200 mV, RO will be high; If A < B by 200 mV, RO will be low. RO will be high also if
the inputs (A and B) are open (non-terminated).
Function
2
I
RE*
Receiver Output Enable: RO is enabled when RE* is low; RO is in TRI-STATE when RE* is high.
3
I
DE
Driver Output Enable: The driver outputs (A and B) are enabled when DE is high; they are in TRI-STATE when DE
is low. Pins A and B also function as the receiver input pins (see below).
4
I
DI
Driver Input: A low on DI forces A low and B high while a high on DI forces A high and B low when the driver is
enabled.
5
NA
GND
6
I/O
A
Non-inverting Driver Output and Receiver Input pin. Driver output levels conform to RS-485 signaling levels.
7
I/O
B
Inverting Driver Output and Receiver Input pin. Driver output levels conform to RS-485 signaling levels.
8
NA
VCC
Ground
Power Supply: 4.75V ≤ VCC ≤ 5.25V
Related TI Low Power RS-485 Transceivers
Part Number
DS36C278
DS36C278T
DS36C279
DS36C279T
DS36C280
DS36C280T
Temperature Range
Number of XCVRs on Bus
0°C to +70°C
128
Ultra Low Power Transceiver
Comments
−40°C to +85°C
64
Ultra Low Power Transceiver
0°C to +70°C
128
Auto-Sleep Mode
−40°C to +85°C
64
Auto-Sleep Mode
0°C to +70°C
128
Adjustable Slew Rate Control
−40°C to +85°C
64
Adjustable Slew Rate Control
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DS485
SNLS122C – JULY 1998 – REVISED APRIL 2013
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APPLICATIONS INFORMATION
The DS485 is a low power transceiver designed for use in RS-485 multipoint applications. The DS485 can
transmit data up to 2.5 Mbps based on a ratio of driver transition time to the unit interval (bit time) of 10%. This
maximum data rate may be further limited by the interconnecting media. The DS485 provides a standard unit
load to the RS-485 bus across the common mode range of −7V to +12V. This allows up to 32 transceivers
(standard unit load) to be connected to the bus. More transceivers may be connected to the bus if they support a
reduced unit load (see Related TI Low Power RS-485 Transceivers). The DS485 also ensures the driver's output
differential voltage into a worst case load that models standard termination loads and 32 unit loads referenced to
the maximum common mode voltage extremes. With a minimum of 1.5V swing into this load, a 1.3V differential
noise margin is supported along with the standard common mode rejection range of the receivers.
Due to the multipoint nature of the bus, contention between drivers may occur. This will not cause damage to the
drivers since they feature short-circuit protection and also thermal shutdown protection. Thermal shutdown
senses die temperature and puts the driver outputs into TRI-STATE if a fault condition occurs that causes
excessive power dissipation which can elevate the junction temperature to +150°C.
A typical multipoint application is shown in the following figure. Note that termination is typically required but is
only located at the two ends of the cable (not on every node). Commonly pull up and pull down resistors may be
required at one end of the bus to provide a failsafe bias. These resistors provide a bias to the line when all
drivers are in TRI-STATE. See Application Note AN-847(SNLA031) for a complete discussion of failsafe biasing
of differention buses.
Figure 15. Multipoint RS-485 Application
8
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SNLS122C – JULY 1998 – REVISED APRIL 2013
REVISION HISTORY
Changes from Revision B (April 2013) to Revision C
•
Page
Changed layout of National Data Sheet to TI format ............................................................................................................ 8
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PACKAGE OPTION ADDENDUM
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25-Aug-2017
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Op Temp (°C)
Device Marking
(4/5)
DS485M
LIFEBUY
SOIC
D
8
95
TBD
Call TI
Call TI
0 to 70
DS485
M
DS485M/NOPB
LIFEBUY
SOIC
D
8
95
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
0 to 70
DS485
M
DS485MX/NOPB
LIFEBUY
SOIC
D
8
2500
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
0 to 70
DS485
M
DS485N/NOPB
LIFEBUY
PDIP
P
8
40
Green (RoHS
& no Sb/Br)
CU SN
Level-1-NA-UNLIM
0 to 70
DS485
N
DS485TM
LIFEBUY
SOIC
D
8
95
TBD
Call TI
Call TI
-40 to 85
DS485
TM
DS485TM/NOPB
LIFEBUY
SOIC
D
8
95
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 85
DS485
TM
DS485TMX/NOPB
LIFEBUY
SOIC
D
8
2500
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 85
DS485
TM
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of