ADM3485EAN [ADI]
ESD Protected, EMC Compliant, 3.3 V, 20 Mbps, EIA RS-485 Transceiver; ESD保护，符合EMC ， 3.3 V ， 20 Mbps的EIA RS- 485收发器
| 型号： | ADM3485EAN |
| 厂家： | 
ADI |
| 描述： | ESD Protected, EMC Compliant, 3.3 V, 20 Mbps, EIA RS-485 Transceiver |
| 文件： | 总11页 (文件大小：121K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
ESD Protected, EMC Compliant, 3.3 V,
20 Mbps, EIA RS-485 Transceiver
a
ADM3485E
FEATURES
FUNCTIONAL BLOCK DIAGRAM
Operates with +3.3 V Supply
ESD Protection: 8 kV Meets IEC1000-4-2
EFT Protection: 2 kV Meets IEC1000-4-4
ADM3485E
EIA RS-422 and RS-485 Compliant Over Full CM Range
19 kꢀ Input Impedance
Up to 50 Transceivers on Bus
20 Mbps Data Rate
R
RO
Short Circuit Protection
Specified Over Full Temperature Range
Thermal Shutdown
Interoperable with 5 V Logic
1 mA Supply Current
2 nA Shutdown Current
B
A
RE
DE
DI
D
8 ns Skew
APPLICATIONS
Telecommunications
DTE-DCE Interface
Packet Switching
Local Area Networks
Data Concentration
Data Multiplexers
Integrated Services Digital Network (ISDN)
AppleTalk
Industrial Controls
GENERAL DESCRIPTION
Excessive power dissipation caused by bus contention or by
output shorting is prevented by a thermal shutdown circuit.
This feature forces the driver output into a high impedance
state if, during fault conditions, a significant temperature
increase is detected in the internal driver circuitry.
The ADM3485E is a low power differential line transceiver
designed to operate using a single +3.3 V power supply. Low
power consumption makes it ideal for power sensitive applica-
tions. It is suitable for communication on multipoint bus trans-
mission lines. Internal protection against electrostatic discharge
(ESD) and electrical fast transient (EFT) allows operation in
electrically harsh environments.
The receiver contains a fail-safe feature that results in a
logic high output state if the inputs are unconnected
(floating).
It is intended for balanced data transmission and complies with
both EIA Standards RS-485 and RS-422. It contains a differen-
tial line driver and a differential line receiver, and is suitable for
half duplex data transfer.
The ADM3485E is fabricated on BiCMOS, an advanced
mixed technology process combining low power CMOS
with fast switching bipolar technology.
The ADM3485E is fully specified over the industrial tem-
perature range and is available in 8-lead DIP and SOIC
packages.
The input impedance is 19 kΩ allowing up to 50 transceivers to
be connected on the bus.
REV. A
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
Fax: 781/326-8703
World Wide Web Site: http://www.analog.com
© Analog Devices, Inc., 2000
(V = +3.3 V ꢁ 0.3 V. All specifications TMIN to TMAX unless otherwise noted.)
ADM3485E–SPECIFICATIONS
CC
Parameter
Min
Typ Max
Units Test Conditions/Comments
DRIVER
Differential Output Voltage, VOD
2.0
1.5
1.5
V
V
V
V
V
V
V
RL = 100 Ω, Figure 1, VCC > 3.1 V
RL = 54 Ω, Figure 1
RL = 60 Ω, Figure 2, –7 V < VTST < +12 V
R = 54 Ω or 100 Ω, Figure 1
R = 54 Ω or 100 Ω, Figure 1
R = 54 Ω or 100 Ω, Figure 1
∆|VOD| for Complementary Output States
Common-Mode Output Voltage VOC
∆|VOC| for Complementary Output States
CMOS Input Logic Threshold Low, VINL
0.2
3
0.2
0.8
CMOS Input Logic Threshold High, VINH 2.0
Logic Input Current (DE, DI, RE)
Output Short Circuit Current
V
µA
mA
1.0
250
VO = –7 V or +12 V
RECEIVER
Differential Input Threshold Voltage, VTH –0.2
+0.2
V
–7 V < VCM < +12 V
VCM = 0 V
–7 V < VCM < +12 V
VIN = +12 V
Input Voltage Hysteresis, ∆VTH
Input Resistance
50
19
+1
–0.8
1
mV
kΩ
mA
mA
µA
V
12
Input Current (A, B)
VIN = –7 V
Logic Enable Input Current (RE)
Output Voltage Low, VOL
Output Voltage High, VOH
0.4
IOUT = +2.5 mA
IOUT = –1.5 mA
VCC – 0.4 V
V
Short Circuit Output Current
Three-State Output Leakage Current
60
1.0
mA
µA
VOUT = GND or VCC
VCC = 3.6 V, 0 V < VOUT < VCC
POWER SUPPLY CURRENT
ICC
Outputs Unloaded,
DE = VCC, RE = 0 V
DE = 0 V, RE = 0 V
DE = 0 V, RE = VCC
1
1
1.2
1.2
1
mA
mA
µA
Supply Current in Shutdown
0.002
ESD/EFT IMMUNITY
ESD Protection
EFT Protection
8
2
kV
kV
IEC1000-4-2 A, B Pins Contact Discharge
IEC1000-4-4, A, B Pins
Specifications subject to change without notice.
–2–
REV. A
ADM3485E
TIMING SPECIFICATIONS (VCC = +3.3 V, TA = +25ꢂC)
Parameter
Min
Typ
Max
Units Test Conditions/ Comments
DRIVER
Differential Output Delay TDD
Differential Output Transition Time
Propagation Delay Input to Output TPLH, TPHL
Driver O/P to O/P TSKEW
1
1
7
35
15
35
8
ns
ns
ns
ns
RL = 60 Ω, CL1 = CL2 = 15 pF, Figure 3
RL = 60 Ω, CL1 = CL2 = 15 pF, Figure 3
RL = 27 Ω, CL1 = CL2 = 15 pF, Figure 7
RL = 54 Ω, CL1 = CL2 = 15 pF, Figure 3
8
22
ENABLE/DISABLE
Driver Enable to Output Valid
Driver Disable Timing
45
40
650
90
80
110
ns
ns
ns
RL = 110 Ω, CL = 50 pF, Figure 2
RL = 110 Ω, CL = 50 pF, Figure 2
RL = 110 Ω, CL = 15 pF, Figure 2
Driver Enable from Shutdown
RECEIVER
Time to Shutdown
Propagation Delay Input to Output TPLH, TPHL
Skew TPLH–TPHL
Receiver Enable TEN
Receiver Disable TDEN
Receiver Enable from Shutdown
80
25
190
65
300
90
10
50
45
ns
ns
ns
ns
ns
ns
CL = 15 pF, Figure 8
CL = 15 pF, Figure 8
CL = 15 pF, Figure 6
CL = 15 pF, Figure 6
CL = 15 pF, Figure 6
25
25
500
Specifications subject to change without notice.
(V = +3.3 V ꢁ 0.3 V, T = TMIN to TMAX
)
TIMING SPECIFICATIONS
CC
A
Parameter
Min
Typ
Max
Units Test Conditions/ Comments
DRIVER
Differential Output Delay TDD
Differential Output Transition Time
Propagation Delay Input to Output TPLH, TPHL
Driver O/P to O/P TSKEW
1
2
7
70
15
70
10
ns
ns
ns
ns
RL = 60 Ω, CL1 = CL2 = 15 pF, Figure 3
RL = 60 Ω, CL1 = CL2 = 15 pF, Figure 3
RL = 27 Ω, CL1 = CL2 = 15 pF, Figure 7
RL = 54 Ω, CL1 = CL2 = 15 pF, Figure 3
8
22
ENABLE/DISABLE
Driver Enable to Output Valid
Driver Disable Timing
Driver Enable from Shutdown
45
40
650
110
110
110
ns
ns
ns
RL = 110 Ω, CL = 50 pF, Figure 2
RL = 110 Ω, CL = 50 pF, Figure 2
RL = 110 Ω, CL = 15 pF, Figure 2
RECEIVER
Time to Shutdown
Propagation Delay Input to Output TPLH, TPHL
Skew TPLH–TPHL
Receiver Enable TEN
Receiver Disable TDEN
Receiver Enable from Shutdown
50
25
190
65
500
115
20
50
50
ns
ns
ns
ns
ns
ns
CL = 15 pF, Figure 8
CL = 15 pF, Figure 8
CL = 15 pF, Figure 6
CL = 15 pF, Figure 6
CL = 15 pF, Figure 6
25
25
600
Specifications subject to change without notice.
REV. A
–3–
ADM3485E
ABSOLUTE MAXIMUM RATINGS*
(TA = +25°C unless otherwise noted)
Operating Temperature Range
Industrial (A Version) . . . . . . . . . . . . . . . . –40°C to +85°C
Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C
Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . +300°C
Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . . +215°C
Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . +220°C
ESD Rating: Air (Human Body Model, All Pins) . . . . . >4 kV
ESD Rating: IEC1000-4-2 Contact (A, B Pins) . . . . . . >8 kV
EFT Rating: IEC1000-4-4 (A, B Pins) . . . . . . . . . . . . . >2 kV
VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7 V
Inputs
Driver Input (DI) . . . . . . . . . . . . . . . . –0.3 V to VCC + 0.3 V
Control Inputs (DE, RE) . . . . . . . . . . –0.3 V to VCC + 0.3 V
Receiver Inputs (A, B) . . . . . . . . . . . . . . . –7.5 V to +12.5 V
Outputs
Driver Outputs . . . . . . . . . . . . . . . . . . . . . –7.5 V to +12.5 V
Receiver Output . . . . . . . . . . . . . . . . . –0.5 V to VCC + 0.5 V
Power Dissipation 8-Lead DIP . . . . . . . . . . . . . . . . . 800 mW
θJA, Thermal Impedance . . . . . . . . . . . . . . . . . . . . 140°C/W
Power Dissipation 8-Lead SOIC . . . . . . . . . . . . . . . . 650 mW
θJA, Thermal Impedance . . . . . . . . . . . . . . . . . . . . 115°C/W
*Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those listed in the operational sections
of this specification is not implied. Exposure to absolute maximum ratings for
extended periods of time may affect device reliability.
ORDERING GUIDE
Model
Temperature Range
Package Description
Package Options
ADM3485EAN
ADM3485EAR
–40°C to +85°C
–40°C to +85°C
Plastic DIP
Small Outline (SOIC)
N-8
SO-8
PIN CONFIGURATION
DIP/SOIC
1
2
3
4
8
7
6
5
RO
V
CC
ADM3485E
B
RE
DE
DI
TOP VIEW
(Not to Scale)
A
GND
PIN FUNCTION DESCRIPTIONS
Mnemonic
Pin
DIP/
SOIC Function
RO
RE
1
2
Receiver Output. High when A > B by 200 mV or low when A < B by 200 mV.
Receiver Output Enable. With RE low, the receiver output RO is enabled. With RE high, the output goes
high impedance. If RE is high and DE low, the ADM3485E enters a shutdown state.
DE
DI
3
4
Driver Output Enable. A high level enables the driver differential outputs, A and B. A low level places it in a
high impedance state.
Driver Input. When the driver is enabled, a logic low on DI forces A low and B high, while a logic high on DI
forces A high and B low.
GND
A
B
5
6
7
8
Ground Connection, 0 V.
Noninverting Receiver Input A/Driver Output A.
Inverting Receiver Input B/Driver Output B.
Power Supply, 3.3 V 0.3 V.
VCC
REV. A
–4–
ADM3485E
Test Circuits
375ꢀ
R/2
R/2
V
OD
V
R
V
OD3
L
TST
V
OC
V
CC
375ꢀ
Figure 1. Driver Voltage Measurement Test Circuit
Figure 5. Driver Voltage Measurement Test Circuit 2
V
CC
V
CC
+1.5V
–1.5V
R
S1
L
R
L
0V OR 3V
DE IN
S1
S2
S2
DE
C
V
RE
L
C
V
L
OUT
OUT
RE IN
Figure 2. Driver Enable/DisableTest Circuit
Figure 6. Receiver Enable/Disable Test Circuit
V
OM
R
L
V
OUT
C
C
S1
L1
DE
DI
IN
C
D
RL
DIFF
L
V
OUT
L2
V
CC
Figure 3. Driver Differential Output Delay Test Circuit
Figure 7. Driver Propagation Delay Test Circuit
3V
0V
A
B
C
C
L1
V
DI
OUT
RO
V
D
RL
R
ID
DIFF
RE
C
RE
L2
L
+1.5V
Figure 4. Driver/Receiver Propagation Delay Test Circuit
Figure 8. Receiver Propagation Delay Test Circuit
REV. A
–5–
ADM3485E
Switching Characteristics
3V
1.5V
tPLH
1.5V
3V
0V
0V
1.5V
tZL
1.5V
DE
tPLH
B
tLZ
1/2 VO
VO
A
1.5V
1.5V
D
O/P
V
V
+ 0.25V
OL
tSKEW
tSKEW
LOW
V
V
OL
VO
90% POINT
90% POINT
tZH
tHZ
0V
OH
O/P
HIGH
D
10% POINT
10% POINT
– 0.25V
OH
–VO
tR
tF
0V
Figure 9. Driver Propagation Delay, Rise/Fall Timing
Figure 11. Driver Enable/Disable Timing
3V
0V
1.5V
tZL
1.5V
RE
0V
0V
A–B
tLZ
tPLH
tPLH
1.5V
1.5V
R
O/P
V
V
+ 0.25V
OL
LOW
V
V
OL
tZH
tHZ
V
OH
OH
O/P
HIGH
R
1.5V
1.5V
– 0.25V
OH
RO
V
OL
0V
Figure 10. Receiver Propagation Delay
Figure 12. Receiver Enable/Disable Timing
REV. A
–6–
Typical Performance Characteristics–ADM3485E
12
14
12
10
8
10
8
6
4
6
4
2
0
2
0
0
0.5
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
1.0
1.5
2.0
2.5
3.0
3.5
OUTPUT LOW VOLTAGE – V
OUTPUT HIGH VOLTAGE – V
Figure 13. Output Current vs. Receiver Output Low
Voltage
Figure 16. Output Current vs. Receiver Output High
Voltage
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
3.30
3.25
3.20
3.15
3.10
3.05
3.00
2.95
2.90
–30
–50
–10
10
30
50
70
90
110
–30
–50
–10
10
30
50
70
90
110
TEMPERATURE –
C
TEMPERATURE – ꢂC
Figure 14. Receiver Output Low Voltage vs. Temperature
Figure 17. Receiver Output High Voltage vs. Temperature
120
100
2.6
2.5
2.4
2.3
2.2
2.1
80
60
40
2.0
1.9
1.8
1.7
1.6
20
0
0.5
0
1.0
1.5
2.0
2.5
3.0
–30
–50
–10
10
30
50
70
90
110
DIFFERENTIAL OUTPUT VOLTAGE – V
TEMPERATURE – ꢂC
Figure 15. Driver Output Current vs. Differential
Output Voltage
Figure 18. Driver Differential Output Voltage vs. Temperature
–7–
REV. A
ADM3485E
100
90
1.20
1.15
80
70
1.10
1.05
I
(mA) DE = V , RE = X
CC
CC
60
50
40
1.00
0.95
0.90
I
(mA) RE = LO, DE = LO
CC
0.85
30
0.80
0.75
20
10
I
(mA)
60
CC
0
–40
0.70
–50
–30
–20
–10
10
30
50
70
90
110
0
20
40
80
TEMPERATURE – ꢂC
TEMPERATURE – ꢂC
Figure 19. Supply Current vs. Temperature
Figure 20. Shutdown Current vs. Temperature
Table I. Comparison of RS-422 and RS-485 Interface Standards
ESD/EFT TRANSIENT PROTECTION SCHEME
The ADM3485E uses protective clamping structures on its
inputs and outputs that clamp the voltage to a safe level and
dissipate the energy present in ESD (Electrostatic) and EFT
(Electrical Fast Transients) discharges.
Specification
RS-422
RS-485
Transmission Type
Maximum Data Rate
Differential
10 MB/s
4000 ft.
2 V
100 Ω
4 kΩ min
200 mV
Differential
10 MB/s
4000 ft.
1.5 V
54 Ω
12 kΩ min
200 mV
Maximum Cable Length
Minimum Driver Output Voltage
Driver Load Impedance
Receiver Input Resistance
Receiver Input Sensitivity
Receiver Input Voltage Range
The protection structure achieves ESD protection up to 8 kV
according to IEC1000-4-2, and EFT protection up to 2 kV on
all I-O lines.
ESD TESTING
Two coupling methods are used for ESD testing, contact dis-
charge and air-gap discharge. Contact discharge calls for a di-
rect connection to the unit being tested. Air-gap discharge uses
a higher test voltage but does not make direct contact with the
unit under test. With air discharge, the discharge gun is moved
toward the unit under test, developing an arc across the air gap,
hence the term air-discharge. This method is influenced by hu-
midity, temperature, barometric pressure, distance and rate of
closure of the discharge gun. The contact-discharge method,
while less realistic, is more repeatable and is gaining acceptance
and preference over the air-gap method.
–7 V to +7 V –7 V to +12 V
No. of Drivers/Receivers Per Line 1/10
32/32
Table II. Transmitting Truth Table
Transmitting
DI
Inputs
DE
Outputs
RE
B
A
X
X
0
1
1
0
0
1
0
X
X
0
1
Hi-Z
Hi-Z
1
0
Hi-Z
Hi-Z
Although very little energy is contained within an ESD pulse,
the extremely fast rise time, coupled with high voltages, can
cause failures in unprotected semiconductors. Catastrophic
destruction can occur immediately as a result of arcing or heat-
ing. Even if catastrophic failure does not occur immediately, the
device may suffer from parametric degradation, which may
result in degraded performance. The cumulative effects of con-
tinuous exposure can eventually lead to complete failure.
1
Table III. Receiving Truth Table
Receiving
Inputs
Outputs
RO
RE
DE
A–B
I-O lines are particularly vulnerable to ESD damage. Simply
touching or plugging in an I-O cable can result in a static dis-
charge that can damage or completely destroy the interface
product connected to the I-O port.
0
0
0
1
X
X
X
X
> +0.2 V
< –0.2 V
Inputs O/C
X
1
0
1
Hi-Z
It is extremely important, therefore, to have high levels of ESD
protection on the I-O lines.
It is possible that the ESD discharge could induce latchup in the
device under test, so it is important that ESD testing on the I-O
pins be carried out while device power is applied. This type of
testing is more representative of a real-world I-O discharge
where the equipment is operating normally when the discharge
occurs.
REV. A
–8–
ADM3485E
Four severity levels are defined in terms of an open-circuit volt-
age as a function of installation environment. The installation
environments are defined as
100%
90%
1. Well-Protected
2. Protected
3. Typical Industrial
4. Severe Industrial
36.8%
10%
V
t
TIME t
tDL
tRL
300ms
16ms
Figure 21. Human Body Model Current Waveform
V
5ns
Table IV. ESD Test Results
50ns
ESD Test Method
I-O Pins
t
IEC1000-4-2: Contact
8 kV
0.2/0.4ms
100%
90%
Figure 23. IEC1000-4-4 Fast Transient Waveform
Table V shows the peak voltages for each of the environments.
Table V. Peak Voltages
Level
V PEAK (kV) PSU
VPEAK (kV) I-O
1
2
3
4
0.5
1
2
0.25
0.5
1
10%
0.1 TO 1ns
4
2
TIME
t
30ns
60ns
A simplified circuit diagram of the actual EFT generator is
illustrated in Figure 24.
Figure 22. IEC1000-4-2 ESD Current Waveform
FAST TRANSIENT BURST IMMUNITY (IEC1000-4-4)
IEC1000-4-4 (previously 801-4) covers electrical fast-transient/
burst (EFT) immunity. Electrical fast transients occur as a
result of arcing contacts in switches and relays. The tests simu-
late the interference generated when, for example, a power relay
disconnects an inductive load. A spark is generated due to the
well known back EMF effect. In fact, the spark consists of a
burst of sparks as the relay contacts separate. The voltage ap-
pearing on the line, therefore, consists of a burst of extremely
fast transient impulses. A similar effect occurs when switching
on fluorescent lights.
C
D
R
R
L
HIGH
VOLTAGE
SOURCE
M
C
50ꢀ
OUTPUT
C
Z
C
S
Figure 24. EFT Generator
These transients are coupled onto the signal lines using an EFT
coupling clamp. The clamp is 1 m long and completely sur-
rounds the cable, providing maximum coupling capacitance
(50 pF to 200 pF typ) between the clamp and the cable. High
energy transients are capacitively coupled onto the signal lines.
Fast rise times (5 ns) as specified by the standard result in very
effective coupling. This test is very severe since high voltages are
coupled onto the signal lines. The repetitive transients can often
cause problems, where single pulses do not. Destructive latchup
may be induced due to the high energy content of the transients.
Note that this stress is applied while the interface products are
powered up and are transmitting data. The EFT test applies
hundreds of pulses with higher energy than ESD. Worst case
transient current on an I-O line can be as high as 40 A.
The fast transient burst test, defined in IEC1000-4-4, simulates
this arcing and its waveform is illustrated in Figure 23. It con-
sists of a burst of 2.5 kHz to 5 kHz transients repeating at
300 ms intervals. It is specified for both power and data lines.
REV. A
–9–
ADM3485E
Test results are classified according to the following
Cable and Data Rate
The transmission line of choice for RS-485 communications is a
twisted pair. Twisted pair cable tends to cancel common-mode
noise and also causes cancellation of the magnetic fields gener-
ated by the current flowing through each wire, thereby reducing
the effective inductance of the pair.
1. Normal performance within specification limits.
2. Temporary degradation or loss of performance that is self-
recoverable.
3. Temporary degradation or loss of function or performance
that requires operator intervention or system reset.
4. Degradation or loss of function that is not recoverable due to
damage.
The ADM3485E is designed for bidirectional data communica-
tions on multipoint transmission lines. A typical application
showing a multipoint transmission network is illustrated in
Figure 23. Only one driver can transmit at a particular time, but
multiple receivers may be enabled simultaneously.
APPLICATIONS INFORMATION
Differential Data Transmission
Differential data transmission is used to reliably transmit data at
high rates over long distances and through noisy environments.
Differential transmission nullifies the effects of ground shifts
and noise signals that appear as common-mode voltages on the
line.
As with any transmission line, it is important that reflections are
minimized. This may be achieved by terminating the extreme
ends of the line using resistors equal to the characteristic imped-
ance of the line. Stub lengths of the main line should also be
kept as short as possible. A properly terminated transmission
line appears purely resistive to the driver.
Two main standards are approved by the Electronics Industries
Association (EIA) which specify the electrical characteristics of
transceivers used in differential data transmission. The RS-422
standard specifies data rates up to 10 MBaud and line lengths
up to 4000 ft. A single driver can drive a transmission line with
up to 10 receivers.
Receiver Open-Circuit Fail-Safe
The receiver input includes a fail-safe feature that guarantees a
logic high on the receiver when the inputs are open circuit or
floating.
The RS-485 standard was defined to cater to true multipoint
communications. This standard meets or exceeds all the re-
quirements of RS-422, but also allows multiple drivers and
receivers to be connected to a single bus. An extended common-
mode range of –7 V to +12 V is defined.
Table VI. Comparison of RS-422 and RS-485 Interface
Standards
Specification
RS-422
RS-485
Transmission Type
Differential Differential
Maximum Cable Length
Minimum Driver Output Voltage 2 V
Driver Load Impedance
Receiver Input Resistance
Receiver Input Sensitivity
Receiver Input Voltage Range
4000 ft.
4000 ft.
1.5 V
The most significant difference between RS-422 and RS-485 is
the fact that the drivers may be disabled thereby allowing more
than one to be connected to a single line. Only one driver should
be enabled at a time, but the RS-485 standard contains addi-
tional specifications to guarantee device safety in the event of
line contention.
100 Ω
54 Ω
4 kΩ min
12 kΩ min
200 mV
200 mV
–7 V to +7 V –7 V to +12 V
REV. A
–10–
ADM3485E
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
8-Lead Plastic DIP
(N-8)
0.430 (10.92)
0.348 (8.84)
8
5
0.280 (7.11)
0.240 (6.10)
1
4
0.325 (8.25)
0.300 (7.62)
0.060 (1.52)
0.015 (0.38)
PIN 1
0.195 (4.95)
0.115 (2.93)
0.210 (5.33)
MAX
0.130
(3.30)
MIN
0.160 (4.06)
0.115 (2.93)
0.015 (0.381)
0.008 (0.204)
SEATING
PLANE
0.100
(2.54)
BSC
0.022 (0.558)
0.014 (0.356)
0.070 (1.77)
0.045 (1.15)
8-Lead SOIC
(SO-8)
0.1968 (5.00)
0.1890 (4.80)
8
1
5
4
0.2440 (6.20)
0.2284 (5.80)
0.1574 (4.00)
0.1497 (3.80)
PIN 1
0.0196 (0.50)
0.0099 (0.25)
0.0500 (1.27)
BSC
ꢃ 45ꢂ
0.0688 (1.75)
0.0532 (1.35)
0.0098 (0.25)
0.0040 (0.10)
SEATING
PLANE
8ꢂ
0ꢂ
0.0500 (1.27)
0.0160 (0.41)
0.0192 (0.49)
0.0138 (0.35)
0.0098 (0.25)
0.0075 (0.19)
REV. A
–11–
相关型号：
ADM3486EARZ-REEL7
3.3 V, 【15 kV ESD-Protected, Half- and Full-Duplex, RS-485/RS-422 Transceivers
ADI
©2020 ICPDF网 联系我们和版权申明