Analog Devices ADM3485E b Datasheet
ESD-Protected, EMC-Compliant, 3.3 V
FEATURES
Operates with 3.3 V supply
ESD protection: 8 kV meets IEC1000-4-2
EFT protection: 2 kV meets IEC1000-4-4
EIA RS-422 and RS-485 compliant over full CM range
19 kΩ input impedance
Up to 50 transceivers on bus
20 Mbps data rate
Short-circuit protection
Specified over full temperature range
Thermal shutdown
Interoperable with 5 V logic
1 mA supply current
2 nA shutdown current
8 ns skew
APPLICATIONS
Telecommunications
DTE-DCE interfaces
Packet switching
Local area networks
Data concentration
Data multiplexers
Integrated services digital network (ISDN)
AppleTalk
Industrial controls
GENERAL DESCRIPTION
The ADM3485E is a low power, differential line transceiver
that operates with a single 3.3 V power supply. Low power
consumption makes it ideal for power-sensitive applications.
It is suitable for communication on multipoint bus transmission
lines. Internal protection against electrostatic discharge (ESD)
and electrical fast transient (EFT) allows operation in electrically harsh environments.
20 Mbps, EIA RS-485 Transceiver
ADM3485E
FUNCTIONAL BLOCK DIAGRAM
ADM3485E
RO
RE
DE
DI
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 receiver contains a fail-safe feature that results in a logic
high output state if the inputs are unconnected (floating).
R
D
Figure 1.
B
A
03338-001
It is intended for balanced data transmission and complies
with both EIA Standards RS-485 and RS-422. It contains a
differential line driver and a differential line receiver, and is
suitable for half-duplex data transfer.
The input impedance is 19 kΩ following up to 50 transceivers to
be connected on the bus.
Rev. B
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 that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
The device 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 temperature range and is available in 8-lead PDIP and SOIC packages.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.326.8703 © 2004 Analog Devices, Inc. All rights reserved.
www.analog.com
ADM3485E
TABLE OF CONTENTS
Specifications..................................................................................... 3
Timing Specifications....................................................................... 4
Absolute Maximum Ratings............................................................ 5
ESD Caution.................................................................................. 5
Pin Configurations and Pin Function Descriptions .................... 6
Test C ir c ui t s ....................................................................................... 7
Switching Characteristics ................................................................ 8
Typical Performance Characteristics ............................................. 9
Standards and Testing .................................................................... 11
REVISION HISTORY
10/04—Data Sheet Changed from Rev. A to Rev. B
Updated Format..................................................................Universal
Changes to Power-Supply Current, Table 1 .................................. 3
Updated Outline Dimensions....................................................... 14
Changes to Ordering Guide.......................................................... 14
5/00—Data Sheet Changed from Rev. 0 to Rev. A
ESD/EFT Transient Protection Scheme .................................. 11
ESD Testing................................................................................. 11
Fast Transient Burst Immunity (IEC1000-4-4)...................... 12
Applications Information .............................................................. 13
Differential Data Transmission ................................................ 13
Cable and Data Rate................................................................... 13
Receiver Open-Circuit Fail-Safe............................................... 13
Outline Dimensions ....................................................................... 14
Ordering Guide .......................................................................... 14
Rev. B | Page 2 of 16
ADM3485E
SPECIFICATIONS
VCC = +3.3 V ± 0.3 V. All specifications T
Table 1.
Parameter Min Typ Max Unit Test Conditions/Comments
DRIVER
Differential Output Voltage, VOD 2.0 V RL= 100 Ω, VCC > 3.1 V; see Figure 3
1.5 V RL= 54 Ω; see Figure 9
1.5 V RL= 60 Ω, see Figure 4; –7 V < V
∆|VOD| for Complementary Output States 0.2 V R = 54 Ω or 100 Ω; see Figure 3
Common-Mode Output Voltage VOC 3 V R = 54 Ω or 100 Ω; see Figure 3
∆|VOC| for Complementary Output States 0.2 V R = 54 Ω or 100 Ω; see Figure 3
CMOS Input Logic Threshold Low, V
CMOS Input Logic Threshold High, V
Logic Input Current (DE, DI, RE)
Output Short-Circuit Current ±250 mA VO = −7 V or +12 V
RECEIVER
Differential Input Threshold Voltage, VTH −0.2 +0.2 V −7 V < VCM < +12 V
Input Voltage Hysteresis, ∆VTH 50 mV VCM = 0 V
Input Resistance 12 19 kΩ −7 V < VCM < +12 V
Input Current (A, B) 1 mA VIN = 12 V
−0.8 mA VIN = −7 V
Logic Enable Input Current (RE)
Output Voltage Low, VOL 0.4 V I
Output Voltage High, VOH VCC – 0.4 V V I
Short-Circuit Output Current ±60 mA V
Three-State Output Leakage Current ±1.0 µA VCC = 3.6 V, 0 V < V
POWER-SUPPLY CURRENT
ICC Outputs unloaded
1 1.5 mA
1 1.5 mA
Supply Current in Shutdown 0.002 1 µA
ESD/EFT IMMUNITY
ESD Protection ±8 kV IEC1000-4-2 A, B pins contact discharge
EFT Protection ±2 kV IEC1000-4-4, A, B pins
to T
MIN
0.8 V
INL
2.0 V
INH
unless otherwise noted.
MAX,
±1.0 µA
±1 µA
= +2.5 mA
OUT
= −1.5 mA
OUT
= GND or VCC
OUT
DE = V
CC
DE = 0 V,
DE = 0 V,
, RE = 0 V
RE = 0 V
RE = VCC
OUT
< VCC
< +12 V
TST
Rev. B | Page 3 of 16
ADM3485E
TIMING SPECIFICATIONS
VCC = 3.3 V, TA = 25°C, unless otherwise noted.
Table 2.
Parameter Min Typ Max Unit Test Conditions/Comments
DRIVER
Differential Output Delay T
DD
Differential Output Transition Time 1 8 15 ns RL = 60 Ω, CL1 = CL2 = 15 pF; see Figure 5
Propagation Delay Input to Output T
Driver Output-to-Output T
SKEW
PLH
, T
PHL
ENABLE/DISABLE
Driver Enable to Output Valid 45 90 ns RL = 110 Ω, CL = 50 pF; see Figure 4
Driver Disable Timing 40 80 ns RL = 110 Ω, CL = 50 pF; see Figure 4
Driver Enable from Shutdown 650 110 ns RL = 110 Ω, CL = 15 pF; see Figure 4
RECEIVER
Time to Shutdown 80 190 300 ns
Propagation Delay Input to Output T
Skew T
PLH–TPHL
Receiver Enable T
Receiver Disable T
EN
DEN
PLH
, T
PHL
Receiver Enable from Shutdown 500 ns CL = 15 pF; see Figure 8
1 35 ns RL = 60 Ω, CL1 = CL2 = 15 pF; see Figure 5
7 22 35 ns RL = 27 Ω, CL1 = CL2 = 15 pF; see Figure 9
8 ns RL = 54 Ω, CL1 = CL2 = 15 pF; see Figure 5
25 65 90 ns CL = 15 pF; see Figure 10
10 ns CL = 15 pF; see Figure 10
25 50 ns CL = 15 pF; see Figure 8
25 45 ns CL = 15 pF; see Figure 8
TIMING SPECIFICATIONS
VCC = 3.3 V ± 0.3 V, TA = T
Table 3.
Parameter Min Typ Max Unit Test Conditions/Comments
DRIVER
Differential Output Delay T
Differential Output Transition Time 2 8 15 ns RL = 60 Ω, CL1 = CL2 = 15 pF; see Figure 5
Propagation Delay Input to Output T
Driver Output-to-Output T
ENABLE/DISABLE
Driver Enable to Output Valid 45 110 ns RL = 110 Ω, CL = 50 pF; see Figure 4
Driver Disable Timing 40 110 ns RL = 110 Ω, CL = 50 pF; see Figure 4
Driver Enable from Shutdown 650 110 ns RL = 110 Ω, CL = 15 pF; see Figure 4
RECEIVER
Time to Shutdown 50 190 500 ns
Propagation Delay Input to Output T
Skew T
Receiver Enable T
Receiver Disable T
PLH
– T
PHL
EN
DEN
Receiver Enable from Shutdown 600 ns CL = 15 pF, Figure 8
MIN
DD
SKEW
to T
, unless otherwise noted.
MAX
, T
PLH
PHL
, T
PLH
PHL
1 70 ns RL = 60 Ω, CL1 = CL2 = 15 pF; see Figure 5
7 22 70 ns RL = 27 Ω, CL1 = CL2 = 15 pF; see Figure 9
10 ns RL = 54 Ω, CL1 = CL2 = 15 pF; see Figure 5
25 65 115 ns CL = 15 pF, Figure 10
20 ns CL = 15 pF, Figure 10
25 50 ns CL = 15 pF, Figure 8
25 50 ns CL = 15 pF, Figure 8
Rev. B | Page 4 of 16
ADM3485E
ABSOLUTE MAXIMUM RATINGS
= +25°C, unless otherwise noted.
T
A
Table 4.
Parameter Values
V
CC
Inputs
Driver Input (DI)
Control Inputs (DE, RE)
Receiver Inputs (A, B)
Outputs
Driver Outputs
Receiver Output
Power Dissipation 8-Lead PDIP 800 mW
θJA, Thermal Impedance 140°C/W
Power Dissipation 8-Lead SOIC 650 mW
θJA, Thermal Impedance 115°C/W
Operating Temperature Range
Industrial (A Version)
Storage Temperature Range
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)
ESD Rating: IEC1000-4-2 Contact
(A, B Pins)
EFT Rating: IEC1000-4-4 (A, B Pins) > 2 kV
7 V
−0.3 V to V
−0.3 V to V
−7.5 V to +12.5 V
−7.5 V to +12.5 V
−0.5 V to V
−40°C to +85°C
−65°C to +150°C
> 4 kV
> 8 kV
+ 0.3 V
CC
+ 0.3 V
CC
+ 0.5 V
CC
Stresses above those listed under Absolute Maximum Ratings
may cause permanent 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.
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on
the human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.
Rev. B | Page 5 of 16
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