AD ADM2687EBRIZ

Preliminary Technical Data
5 kV rms Signal & Power Isolated RS-485
Transceiver with ±15 kV ESD Protection
ADM2682E/ADM2687E
FEATURES
5 kV rms isolated RS-485/RS-422 transceiver, configurable as
half or full duplex
isoPower® integrated isolated dc-to-dc converter
±15 kV ESD protection on RS-485 input/output pins
Complies with ANSI/TIA/EIA-485-A-98 and ISO 8482:1987(E)
Data rate: 16 Mbps (ADM2682E), 500 kbps (ADM2687E)
5 V or 3.3 V operation
Connect up to 256 nodes on one bus
Open- and short-circuit, fail-safe receiver inputs
High common-mode transient immunity: >25 kV/µs
Thermal shutdown protection
Safety and regulatory approvals
UL recognition (pending)
5000 V rms for 1 minute per UL 1577
CSA Component Acceptance Notice #5A (pending)
IEC 60601-1: 400 V rms (basic), 250 V rms (reinforced)
IEC 60950-1: 600 V rms (basic), 380 V rms (reinforced)
VDE Certificates of Conformity (pending)
DIN EN 60747-5-2 (VDE 0884 Part 2): 2003-01
VIORM = 846 V peak
Operating temperature range: −40°C to +85°C
16-lead wide-body SOIC with >8 mm creepage and clearance
FUNCTIONAL BLOCK DIAGRAM
VISOOUT
VCC
isoPower DC-TO-DC CONVERTER
OSCILLATOR
RECTIFIER
VISOIN
REGULATOR
TRANSCEIVER
DIGITAL ISOLATION iCoupler
Y
TxD
ENCODE
DECODE
D
Z
DE
ENCODE
DECODE
RxD
DECODE
ENCODE
A
R
B
ADM2682E/ADM2687E
RE
GND1
ISOLATION
BARRIER
GND2
Figure 1.
APPLICATIONS
Isolated RS-485/RS-422 interfaces
Industrial field networks
Multipoint data transmission systems
GENERAL DESCRIPTION
The ADM2682E/ADM2687E are fully integrated 5 kV rms
signal and power isolated data transceivers with ±15 kV ESD
protection and are suitable for high speed communication on
multipoint transmission lines. The ADM2682E/ADM2687E
include an integrated 5 kV rms isolated dc-to-dc power supply,
which eliminates the need for an external dc-to-dc isolation
block.
The ADM2682E/ADM2687E driver has an active high enable.
An active low receiver enable is also provided, which causes the
receiver output to enter a high impedance state when disabled.
They are designed for balanced transmission lines and comply
with ANSI/TIA/EIA-485-A-98 and ISO 8482:1987(E).
The devices have current limiting and thermal shutdown
features to protect against output short circuits and situations
where bus contention may cause excessive power dissipation.
The parts are fully specified over the industrial temperature
range and are available in a highly integrated, 16-lead, widebody SOIC package with >8 mm creepage and clearance.
The devices integrate Analog Devices, Inc., iCoupler® technology to
combine a 3-channel isolator, a three-state differential line driver, a
differential input receiver, and Analog Devices isoPower dc-todc converter into a single package. The devices are powered by a
single 5 V or 3.3 V supply, realizing a fully integrated signal and
power isolated RS-485 solution.
The ADM2682E/ADM2687E contain isoPower technology that
uses high frequency switching elements to transfer power through
the transformer. Special care must be taken during printed circuit
board (PCB) layout to meet emissions standards. Refer to
Application Note AN-0971, Control of Radiated Emissions with
isoPower Devices, for details on board layout considerations.
Rev. PrE
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rights of third parties that may result from its use. Specifications subject to change without notice. No
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Fax: 781.461.3113
©2011 Analog Devices, Inc. All rights reserved.
ADM2682E/ADM2687E
Preliminary Technical Data
TABLE OF CONTENTS
Features .............................................................................................. 1
Test Circuits..................................................................................... 13
Applications ....................................................................................... 1
Switching Characteristics .............................................................. 14
Functional Block Diagram .............................................................. 1
Circuit Description......................................................................... 15
General Description ......................................................................... 1
Signal Isolation ........................................................................... 15
Specifications..................................................................................... 3
Power Isolation ........................................................................... 15
ADM2682E Timing Specifications ............................................ 4
Truth Tables................................................................................. 15
ADM2687E Timing Specifications ............................................ 4
Thermal Shutdown .................................................................... 15
ADM2682E/ADM2687E Package Characteristics ................... 4
Open- and Short-Circuit, Fail-Safe Receiver Inputs.............. 15
ADM2682E/ADM2687E Regulatory Information .................. 5
DC Correctness and Magnetic Field Immunity .......................... 16
ADM2682E/ADM2687E Insulation and Safety-Related
Specifications ................................................................................ 5
Applications Information .............................................................. 17
ADM2682E/ADM2687E VDE 0884 Insulation
Characteristics (Pending) ............................................................ 6
EMI Considerations ................................................................... 17
Absolute Maximum Ratings............................................................ 7
ESD Caution .................................................................................. 7
Pin Configuration and Function Descriptions ............................. 8
Typical Performance Characteristics ............................................. 9
PCB Layout ................................................................................. 17
Insulation Lifetime ..................................................................... 17
Typical Applications ................................................................... 18
Outline Dimensions ....................................................................... 20
Ordering Guide .......................................................................... 20
Rev. PrE | Page 2 of 20
Preliminary Technical Data
ADM2682E/ADM2687E
SPECIFICATIONS
All voltages are relative to their respective ground; 3.0 ≤ VCC ≤ 5.5 V. All minimum/maximum specifications apply over the entire
recommended operation range, unless otherwise noted. All typical specifications are at TA = 25°C, VCC = 5 V unless otherwise noted.
Table 1.
Parameter
ADM2687E SUPPLY CURRENT
Data Rate ≤ 500 kbps
Symbol
ICC
ADM2682E SUPPLY CURRENT
Data Rate = 16 Mbps
ICC
ISOLATED SUPPLY VOLTAGE
DRIVER
Differential Outputs
Differential Output Voltage, Loaded
VISOUT
Δ|VOD| for Complementary Output States
Common-Mode Output Voltage
Δ|VOC| for Complementary Output States
Short-Circuit Output Current
Output Leakage Current (Y, Z)
���, TxD
Logic Inputs DE, RE
Input Threshold Low
Input Threshold High
Input Current
RECEIVER
Differential Inputs
Differential Input Threshold Voltage
Input Voltage Hysteresis
Input Current (A, B)
Line Input Resistance
Logic Outputs
Output Voltage Low
Output Voltage High
Short-Circuit Current
COMMON-MODE TRANSIENT IMMUNITY 1
1
Min
Typ
Max
Unit
Test Conditions
120
mA
mA
mA
mA
mA
VCC = 3.3 V, 100 Ω load between Y and Z
VCC = 5 V, 100 Ω load between Y and Z
VCC = 3.3 V, 54 Ω load between Y and Z
VCC = 5 V, 54 Ω load between Y and Z
120 Ω load between Y and Z
150
230
mA
mA
120 Ω load between Y and Z
54 Ω load between Y and Z
3.6
3.6
3.6
0.2
3.0
0.2
200
30
V
V
V
V
V
V
mA
µA
RL = 100 Ω (RS-422), see Figure 23
RL = 54 Ω (RS-485), see Figure 23
−7 V ≤ VTEST1 ≤ 12 V, see Figure 24
RL = 54 Ω or 100 Ω, see Figure 23
RL = 54 Ω or 100 Ω, see Figure 23
RL = 54 Ω or 100 Ω, see Figure 23
90
72
125
98
|VOD2|
|VOD3|
Δ|VOD|
VOC
Δ|VOC|
IOS
IO
3.3
2.0
1.5
1.5
DE = 0 V, ���
RE = 0 V, VCC = 0 V or 3.6 V,
VIN = 12 V
DE = 0 V, ���
RE = 0 V, VCC = 0 V or 3.6 V,
VIN = −7 V
−30
µA
VIL
VIH
II
0.3 × VCC
−10
0.01
V
V
µA
���, TxD
DE, RE
���, TxD
DE, RE
���, TxD
DE, RE
VTH
VHYS
II
−200
−125
15
mV
mV
µA
µA
kΩ
−7 V < VCM < +12 V
VOC = 0 V
DE = 0 V, VCC = 0 V or 3.6 V, VIN = 12 V
DE = 0 V, VCC = 0 V or 3.6 V, VIN = -7 V
−7 V < VCM < +12 V
V
V
mA
kV/µs
IO = 1.5 mA, VA − VB = −0.2 V
IO = −1.5 mA, VA − VB = 0.2 V
0.7 × VCC
10
−30
125
RIN
−100
96
VOL
VOH
VCC − 0.3
0.2
VCC − 0.2
0.4
100
25
VCM = 1 kV, transient magnitude = 800 V
CM is the maximum common-mode voltage slew rate that can be sustained while maintaining specification-compliant operation. VCM is the common-mode potential
difference between the logic and bus sides. The transient magnitude is the range over which the common-mode is slewed. The common-mode voltage slew rates
apply to both rising and falling common-mode voltage edges.
Rev. PrE | Page 3 of 20
ADM2682E/ADM2687E
Preliminary Technical Data
ADM2682E TIMING SPECIFICATIONS
TA = −40°C to +85°C.
Table 2.
Parameter
DRIVER
Maximum Data Rate
Propagation Delay, Low to High
Propagation Delay, High to Low
Output Skew
Rise Time/Fall Time
Enable Time
Disable Time
RECEIVER
Propagation Delay, Low to High
Propagation Delay, High to Low
Output Skew 1
Enable Time
Disable Time
1
Symbol
Min
Typ
Max
Unit
Test Conditions
RL = 54 Ω, CL1 = C L2 = 100 pF, see Figure 25 and Figure 29
RL = 54 Ω, CL1 = C L2 = 100 pF, see Figure 25 and Figure 29
RL = 54 Ω, CL1 = CL2 = 100 pF, see Figure 25 and Figure 29
RL = 54 Ω, CL1 = CL2 = 100 pF, see Figure 25 and Figure 29
RL = 110 Ω, CL = 50 pF, see Figure 26 and Figure 31
RL = 110 Ω, CL = 50 pF, see Figure 26 and Figure 31
CL = 15 pF, see Figure 27 and Figure 30
CL = 15 pF, see Figure 27 and Figure 30
CL = 15 pF, see Figure 27 and Figure 30
RL = 1 kΩ, CL = 15 pF, see Figure 28 and Figure 32
RL = 1 kΩ, CL = 15 pF, see Figure 28 and Figure 32
16
tDPLH
tDPHL
tSKEW
tDR, tDF
tZL, tZH
tLZ, tHZ
63
64
1
100
100
8
15
120
150
Mbps
ns
ns
ns
ns
ns
ns
tRPLH
tRPHL
tSKEW
tZL, tZH
tLZ, tHZ
94
95
1
110
110
12
15
15
ns
ns
ns
ns
ns
Typ
Max
Unit
Test Conditions
503
510
7
700
700
100
1100
2.5
200
kbps
ns
ns
ns
ns
µs
ns
RL = 54 Ω, CL1 = C L2 = 100 pF, see Figure 25 and Figure 29
RL = 54 Ω, CL1 = C L2 = 100 pF, see Figure 25 and Figure 29
RL = 54 Ω, CL1 = CL2 = 100 pF, see Figure 25 and Figure 29
RL = 54 Ω, CL1 = CL2 = 100 pF, see Figure 25 and Figure 29
RL = 110 Ω, CL = 50 pF, see Figure 26 and Figure 31
RL = 110 Ω, CL = 50 pF, see Figure 26 and Figure 31
91
95
4
200
200
30
15
15
ns
ns
ns
ns
ns
CL = 15 pF, see Figure 27 and Figure 30
CL = 15 pF, see Figure 27 and Figure 30
CL = 15 pF, see Figure 27 and Figure 30
RL = 1 kΩ, CL = 15 pF, see Figure 28 and Figure 32
RL = 1 kΩ, CL = 15 pF, see Figure 28 and Figure 32
Guaranteed by design.
ADM2687E TIMING SPECIFICATIONS
TA = −40°C to +85°C.
Table 3.
Parameter
DRIVER
Maximum Data Rate
Propagation Delay, Low to High
Propagation Delay, High to Low
Output Skew
Rise Time/Fall Time
Enable Time
Disable Time
RECEIVER
Propagation Delay, Low to High
Propagation Delay, High to Low
Output Skew
Enable Time
Disable Time
Symbol
tDPLH
tDPHL
tSKEW
tDR, tDF
tZL, tZH
tLZ, tHZ
tRPLH
tRPHL
tSKEW
tZL, tZH
tLZ, tHZ
Min
500
250
250
200
ADM2682E/ADM2687E PACKAGE CHARACTERISTICS
Table 4.
Parameter
Resistance (Input-to-Output) 1
Capacitance (Input-to-Output)1
Input Capacitance 2
1
2
Symbol
RI-O
CI-O
CI
Min
Typ
1012
3
4
Max
Device considered a 2-terminal device: short together Pin 1 to Pin 8 and short together Pin 9 to Pin 16.
Input capacitance is from any input data pin to ground.
Rev. PrE | Page 4 of 20
Unit
Ω
pF
pF
Test Conditions
f = 1 MHz
Preliminary Technical Data
ADM2682E/ADM2687E
ADM2682E/ADM2687E REGULATORY INFORMATION
Table 5. ADM2682E/ADM2687E Approvals
Organization
UL (Pending)
Approval Type
To be recognized under the UL 1577 Component Recognition Program of Underwriters Laboratories, Inc.
Single Protection, 5000 V rms isolation voltage
CSA (Pending)
In accordance with UL 1577, each ADM2682E/ADM2687E is proof tested by applying an insulation test voltage ≥ 6000 V
rms for 1 second.
To be approved under CSA Component Acceptance Notice #5A
VDE (Pending)
Reinforced insulation per IEC 60601-1, 250 V rms(353 V peak) maximum working voltage
Basic insulation per IEC 60601-1, 400 V rms (566 V peak) maximum working voltage
Reinforced insulation per CSA 60950-1-03 and IEC 60950-1, 380 V rms (537 V peak) maximum working voltage
Basic insulation per CSA 60950-1-03 and IEC 60950-1, 600 V rms (848 V peak) maximum working voltage
To be certified according to DIN EN 60747-5-2 (VDE 0884 Rev. 2): 2003-01
In accordance with DIN EN 60747-5-2, each ADM2682E/ADM2687E is proof tested by applying an insulation test voltage
≥ 1590 VPEAK for 1 second.
ADM2682E/ADM2687E INSULATION AND SAFETY-RELATED SPECIFICATIONS
Table 6.
Parameter
Rated Dielectric Insulation Voltage
Minimum External Air Gap (Clearance)
Symbol
L(I01)
Value
5000
>8.0
Unit
V rms
mm
Minimum External Tracking (Creepage)
L(I02)
>8.0
mm
Minimum Internal Gap (Internal Clearance)
Tracking Resistance (Comparative Tracking Index)
Isolation Group
CTI
0.017 min
>175
IIIa
mm
V
Rev. PrE | Page 5 of 20
Conditions
1-minute duration
Measured from input terminals to output terminals,
shortest distance through air
Measured from input terminals to output terminals,
shortest distance along body
Insulation distance through insulation
DIN IEC 112/VDE 0303-1
Material Group (DIN VDE 0110: 1989-01, Table 1)
ADM2682E/ADM2687E
Preliminary Technical Data
ADM2682E/ADM2687E VDE 0884 INSULATION CHARACTERISTICS (PENDING)
This isolator is suitable for reinforced electrical isolation only within the safety limit data. Maintenance of the safety data must be ensured
by means of protective circuits.
Table 7.
Description
CLASSIFICATIONS
Installation Classification per DIN VDE 0110 for
Rated Mains Voltage
≤300 V rms
≤450 V rms
≤600 V rms
Climatic Classification
Pollution Degree
VOLTAGE
Maximum Working Insulation Voltage
Input-to-Output Test Voltage
Method b1
Method a
After Environmental Tests, Subgroup 1
After Input and/or Safety Test,
Subgroup 2/Subgroup 3
Highest Allowable Overvoltage
SAFETY-LIMITING VALUES
Case Temperature
Input Current
Output Current
Insulation Resistance at TS
Conditions
Symbol
Characteristic
Unit
I to IV
I to III
I to II
40/85/21
2
DIN VDE 0110, see Table 1
VIORM
VPR
846
V peak
VIORM × 1.875 = VPR, 100% production tested,
tm = 1 sec, partial discharge < 5 pC
1590
V peak
VIORM × 1.6 = VPR, tm = 60 sec, partial discharge < 5 pC
VIORM × 1.2 = VPR, tm = 60 sec, partial discharge < 5 pC
1375
1018
V peak
V peak
VTR
6000
V peak
TS
IS, INPUT
IS, OUTPUT
RS
150
265
335
>109
°C
mA
mA
Ω
Transient overvoltage, tTR = 10 sec
Maximum value allowed in the event of a failure
VIO = 500 V
Rev. PrE | Page 6 of 20
Preliminary Technical Data
ADM2682E/ADM2687E
ABSOLUTE MAXIMUM RATINGS
TA = 25°C, unless otherwise noted. All voltages are relative to
their respective ground.
Table 8.
Parameter
VCC
Digital Input Voltage (DE, ���
RE, TxD)
Digital Output Voltage (RxD)
Driver Output/Receiver Input Voltage
Operating Temperature Range
Storage Temperature Range
ESD (Human Body Model) on
A, B, Y, and Z pins
ESD (Human Body Model) on Other Pins
Thermal Resistance θJA
Lead Temperature
Soldering (10 sec)
Vapor Phase (60 sec)
Infrared (15 sec)
Rating
−0.5 V to +7 V
−0.5 V to VDD + 0.5 V
−0.5 V to VDD + 0.5 V
−9 V to +14 V
−40°C to +85°C
−55°C to +150°C
±15 kV
±2 kV
52°C/W
260°C
215°C
220°C
Table 9. Maximum Continuous Working Voltage1
Parameter
AC Voltage
Bipolar Waveform
Max
Unit
Reference Standard
424
V peak
All certifications,
50-year minimum
lifetime
Unipolar Waveform
Basic Insulation
Reinforced Insulation
600
537
V peak
V peak
DC Voltage
Basic Insulation
Reinforced Insulation
600
537
V peak
V peak
1
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 indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
Maximum approved
working voltage per
IEC 60950-1
Maximum approved
working voltage per
IEC 60950-1
Refers to continuous voltage magnitude imposed across the isolation
barrier. See the Insulation Lifetime section for more details.
ESD CAUTION
Rev. PrE | Page 7 of 20
ADM2682E/ADM2687E
Preliminary Technical Data
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
GND1 1
16 GND2
VCC 2
15 VISOIN
RxD 3
ADM2682E
ADM2687E
14 A
13 B
TOP VIEW
DE 5 (Not to Scale) 12 Z
RE 4
TxD 6
11 Y
VCC 7
10 VISOOUT
GND1 8
9
GND2
NOTES:
1. PIN 10 AND PIN 15 MUST BE
CONNECTED EXTERNALLY
Figure 2. Pin Configuration
Table 10. Pin Function Description
Pin No.
1
2
Mnemonic
GND1
VCC
3
RxD
4
���
RE
5
6
7
DE
TxD
VCC
8
9
10
GND1
GND2
VISOOUT
11
12
13
14
15
Y
Z
B
A
VISOIN
16
GND2
Description
Ground, Logic Side.
Logic Side Power Supply. It is recommended that a 0.1 µF and a 0.01 µF decoupling capacitor be fitted between
Pin 2 and Pin 1.
Receiver Output Data. This output is high when (A − B) ≥ -30 mV and low when (A − B) ≤ –200 mV.
��� is driven high.
The output is tristated when the receiver is disabled, that is, when RE
Receiver Enable Input. This is an active-low input. Driving this input low enables the receiver; driving it
high disables the receiver.
Driver Enable Input. Driving this input high enables the driver; driving it low disables the driver.
Driver Input. Data to be transmitted by the driver is applied to this input.
Logic Side Power Supply. It is recommended that a 0.1 µF and a 10 µF decoupling capacitor be fitted between
Pin 7 and Pin 8.
Ground, Logic Side.
Ground, Bus Side.
Isolated Power Supply Output. This pin must be connected externally to VISOIN. It is recommended that a reservoir
capacitor of 10 µF and a decoupling capacitor of 0.1 µF be fitted between Pin 10 and Pin 9.
Driver Noninverting Output
Driver Inverting Output
Receiver Inverting Input.
Receiver Noninverting Input.
Isolated Power Supply Input. This pin must be connected externally to VISOOUT. It is recommended that a
0.1 µF and a 0.01 µF decoupling capacitor be fitted between Pin 15 and Pin 16.
Ground, Bus Side.
Rev. PrE | Page 8 of 20
Preliminary Technical Data
ADM2682E/ADM2687E
TYPICAL PERFORMANCE CHARACTERISTICS
180
140
120
RL = 54Ω
140
RL = 54Ω
SUPPLY CURRENT, ICC (mA)
120
RL = 120Ω
100
80
NO LOAD
60
40
80
RL = 120Ω
60
40
NO LOAD
20
20
–15
10
35
TEMPERATURE (°C)
60
85
0
–40
08111-103
0
–40
100
Figure 3. ADM2682E Supply Current (ICC) vs. Temperature
(Data Rate = 16 Mbps, DE = 3.3 V, VCC = 3.3 V)
–15
10
35
TEMPERATURE (°C)
60
85
08111-105
SUPPLY CURRENT, ICC (mA)
160
Figure 6. ADM2687E Supply Current (ICC) vs. Temperature
(Data Rate = 500 kbps, DE = 3.3 V, VCC = 3.3 V)
140
72
70
SUPPLY CURRENT, ICC (mA)
DRIVER PROPAGATION DELAY (ns)
RL = 54Ω
120
100
RL = 120Ω
80
60
NO LOAD
40
20
68
66
64
tDPHL
62
tDPLH
60
58
56
54
10
35
TEMPERATURE (°C)
60
85
50
–40
08111-104
–15
Figure 4. ADM2682E Supply Current (ICC) vs. Temperature
(Data Rate = 16 Mbps, DE = 5 V, VCC = 5 V)
–15
10
35
TEMPERATURE (°C)
60
85
08111-107
52
0
–40
Figure 7. ADM2682E Differential Driver Propagation Delay vs. Temperature
120
600
DRIVER PROPAGATION DELAY (ns)
580
RL = 54Ω
80
RL = 120Ω
60
40
NO LOAD
20
560
540
tDPLH
520
tDPHL
500
480
460
440
0
–40
–15
10
35
TEMPERATURE (°C)
60
Figure 5. ADM2687E Supply Current (ICC) vs. Temperature
(Data Rate = 500 kbps, DE = 5 V, VCC = 5 V)
85
400
–40
–15
10
35
TEMPERATURE (°C)
60
85
08111-108
420
08111-106
SUPPLY CURRENT, ICC (mA)
100
Figure 8. ADM2687E Differential Driver Propagation Delay vs. Temperature
Rev. PrE | Page 9 of 20
ADM2682E/ADM2687E
Preliminary Technical Data
60
TxD
OUTPUT CURRENT (mA)
50
1
Z
40
30
20
Y
CH2 2.0V
M10.00ns
A CH1
1.28V
08111-109
CH1 2.0V
CH3 2.0V
0
0
Figure 9. ADM2682E Driver Propagation Delay
1
2
3
OUTPUT VOLTAGE (V)
4
5
08111-112
10
3
Figure 12. Receiver Output Current vs. Receiver Output Low Voltage
4.75
4.74
OUTPUT VOLTAGE(V)
4.73
TxD
1
Z
Y
4.72
4.71
4.70
4.69
4.68
4.67
3
CH2 2.0V
M200ns
A CH1
2.56V
4.65
–40
Figure 10. ADM2687E Driver Propagation Delay
10
35
TEMPERATURE (°C)
60
85
Figure 13. Receiver Output High Voltage vs. Temperature
0
0.32
–10
0.30
–20
OUTPUT VOLTAGE (V)
–30
–40
–50
0.28
0.26
0.24
0.22
–70
0
1
2
3
OUTPUT VOLTAGE (V)
4
5
08111-111
–60
Figure 11. Receiver Output Current vs. Receiver Output High Voltage
Rev. PrE | Page 10 of 20
0.20
–40
–15
10
35
TEMPERATURE (°C)
60
Figure 14. Receiver Output Low Voltage vs. Temperature
85
08111-114
OUTPUT CURRENT (mA)
–15
08111-113
CH1 2.0V
CH3 2.0V
08111-110
4.66
Preliminary Technical Data
ADM2682E/ADM2687E
B
A
1
RxD
3
CH2 2.0V
M10.00ns
A CH1
2.56V
98
97
96
tRPHL
95
94
93
92
tRPLH
91
90
–40
08111-115
CH1 2.0V
CH3 2.0V
99
–15
10
35
TEMPERATURE (°C)
60
85
08111-118
RECEIVER PROPAGATION DELAY (ns)
100
Figure 18. ADM2687E Receiver Propagation Delay vs. Temperature
Figure 15. ADM2682E Receiver Propagation Delay
3.33
ISOLATED SUPPLY VOLTAGE (V)
A
B
1
RxD
3.31
3.30
3.29
NO LOAD
RL = 120Ω
RL = 54Ω
3.28
CH2 2.0V
M10.00ns
A CH1
2.56V
3.26
–40
08111-116
CH1 2.0V
CH3 2.0V
–15
10
35
TEMPERATURE (°C)
60
85
08111-119
3.27
3
Figure 19. ADM2682E Isolated Supply Voltage vs. Temperature
(VCC = 3.3 V, Data Rate = 16 Mbps)
Figure 16. ADM2687E Receiver Propagation Delay
98
3.36
3.35
96
tRPHL
95
tRPLH
94
93
3.34
3.33
3.32
3.31
3.30
3.29
NO LOAD
RL = 120Ω
RL = 54Ω
3.28
92
–40
–15
10
35
TEMPERATURE (°C)
60
85
08111-117
3.27
Figure 17. ADM2682E Receiver Propagation Delay vs. Temperature
Rev. PrE | Page 11 of 20
3.26
–40
–15
10
35
TEMPERATURE (°C)
60
85
Figure 20. ADM2682E Isolated Supply Voltage vs. Temperature
(VCC = 5 V, Data Rate = 16 Mbps)
08111-120
97
ISOLATED SUPPLY VOLTAGE (V)
RECEIVER PROPAGATION DELAY (ns)
3.32
ADM2682E/ADM2687E
Preliminary Technical Data
60
40
RL = 54Ω
ISOLATED SUPPLY CURRENT (mA)
35
50
40
RL = 120Ω
30
NO LOAD
20
10
30
RL = 120Ω
25
20
15
10
NO LOAD
0
–40
–15
10
35
TEMPERATURE (°C)
60
85
0
–40
–15
10
35
TEMPERATURE (°C)
60
85
Figure 22. ADM2687E Isolated Supply Current vs. Temperature
(VCC = 3.3 V, Data Rate = 500 kbps)
Figure 21. ADM2682E Isolated Supply Current vs. Temperature
(VCC = 3.3 V, Data Rate = 16 Mbps)
Rev. PrE | Page 12 of 20
08111-122
5
08111-121
ISOLATED SUPPLY CURRENT (mA)
RL = 54Ω
Preliminary Technical Data
ADM2682E/ADM2687E
TEST CIRCUITS
RL
2
VOD2
RL
2
Z
VOUT
Y
VOC
08111-003
TxD
S1
Y
Figure 26. Driver Enable/Disable
375Ω
A
375Ω
VTEST
B
Figure 24. Driver Voltage Measurement
Y
CL
Figure 27. Receiver Propagation Delay
VCC
+1.5V
CL
S1
RL
CL
RL
–1.5V
RE
08111-005
Z
VOUT
RE
S2
CL
VOUT
RE IN
Figure 25. Driver Propagation Delay
Figure 28. Receiver Enable/Disable
Rev. PrE | Page 13 of 20
08111-008
Z
08111-007
60Ω
08111-004
VOD3
TxD
S2
CL
50pF
Z
DE
Figure 23. Driver Voltage Measurement
TxD
VCC
RL
110Ω
08111-006
Y
TxD
ADM2682E/ADM2687E
Preliminary Technical Data
SWITCHING CHARACTERISTICS
VCC
VCC/2
VCC/2
0V
tDPLH
tDPHL
VCC
Z
1/2VO
DE
0.5VCC
0.5VCC
VO
0V
tZL
Y
Y, Z
90% POINT
VDIFF
VOL
tZH
10% POINT
10% POINT
tDF
tDR
tHZ
2.3V
VOH
VOH – 0.5V
Y, Z
08111-011
–VO
VOL + 0.5V
90% POINT
VDIFF = V(Y) – V(Z)
08111-009
+VO
tLZ
2.3V
tSKEW = │tDPHL – tDPLH │
Figure 31. Driver Enable/Disable Timing
Figure 29. Driver Propagation Delay, Rise/Fall Timing
0.7VCC
RE
0.5VCC
0.5VCC
0.3VCC
0V
0V
tRPLH
tRPHL
tZL
1.5V
RO
VOH
tLZ
VOL + 0.5V
OUTPUT LOW
tZH
VOL
tHZ
OUTPUT HIGH
1.5V
tSKEW = |tRPLH – tRPHL |
1.5V
VOL
08111-010
RxD
RO
1.5V
VOH – 0.5V
0V
Figure 32. Receiver Enable/Disable Timing
Figure 30. Receiver Propagation Delay
Rev. PrE | Page 14 of 20
VOH
08111-012
A–B
Preliminary Technical Data
ADM2682E/ADM2687E
CIRCUIT DESCRIPTION
SIGNAL ISOLATION
The ADM2682E/ADM2687E signal isolation of 5 kV rms is
implemented on the logic side of the interface. The part achieves
signal isolation by having a digital isolation section and a
transceiver section (see Figure 1). Data applied to the TxD and
DE pins and referenced to logic ground (GND1) are coupled
across an isolation barrier to appear at the transceiver section
referenced to isolated ground (GND2). Similarly, the single-ended
receiver output signal, referenced to isolated ground in the
transceiver section, is coupled across the isolation barrier to
appear at the RXD pin referenced to logic ground.
POWER ISOLATION
The ADM2682E/ADM2687E power isolation of 5 kV rms is
implemented using an isoPower integrated isolated dc-to-dc
converter. The dc-to-dc converter section of the
ADM2682E/ADM2687E works on principles that are common
to most modern power supplies. It is a secondary side controller
architecture with isolated pulse-width modulation (PWM)
feedback. VCC power is supplied to an oscillating circuit that
switches current into a chip-scale air core transformer. Power
transferred to the secondary side is rectified and regulated to
3.3 V. The secondary (VISO) side controller regulates the output
by creating a PWM control signal that is sent to the primary
(VCC) side by a dedicated iCoupler (5 kV rms signal isolated)
data channel. The PWM modulates the oscillator circuit to
control the power being sent to the secondary side. Feedback
allows for significantly higher power and efficiency.
TRUTH TABLES
The truth tables in this section use the abbreviations found in
Table 11.
Table 11. Truth Table Abbreviations
Letter
H
L
X
I
Z
NC
Description
High level
Low level
Don’t care
Indeterminate
High impedance (off )
Disconnected
Table 13. Receiving (see Table 11 for Abbreviations)
Inputs
A−B
≥ −0.03 V
≤ −0.2 V
−0.2 V < A − B < −0.03 V
Inputs open
X
DE
H
H
L
X
TxD
H
L
X
X
The ADM2682E/ADM2687E contain thermal shutdown circuitry
that protects the parts from excessive power dissipation during
fault conditions. Shorting the driver outputs to a low impedance
source can result in high driver currents. The thermal sensing
circuitry detects the increase in die temperature under this
condition and disables the driver outputs. This circuitry is
designed to disable the driver outputs when a die temperature
of 150°C is reached. As the device cools, the drivers are reenabled
at a temperature of 140°C.
OPEN- AND SHORT-CIRCUIT, FAIL-SAFE RECEIVER
INPUTS
The receiver inputs have open- and short-circuit, fail-safe
features that ensure that the receiver output is high when the
inputs are open or shorted. During line-idle conditions, when no
driver on the bus is enabled, the voltage across a terminating
resistance at the receiver input decays to 0 V. With traditional
transceivers, receiver input thresholds specified between -200 mV
and +200 mV mean that external bias resistors are required on the
A and B pins to ensure that the receiver outputs are in a known
state. The short-circuit, fail-safe receiver input feature eliminates
the need for bias resistors by specifying the receiver input
threshold between -30 mV and -200 mV. The guaranteed negative
threshold means that when the voltage between A and B decays
to 0 V, the receiver output is guaranteed to be high.
Outputs
Y
H
L
Z
Z
RxD
H
L
I
H
Z
THERMAL SHUTDOWN
Table 12. Transmitting (see Table 11 for Abbreviations)
Inputs
Output
�RE
���
L or NC
L or NC
L or NC
L or NC
H
Z
L
H
Z
Z
Rev. PrE | Page 15 of 20
ADM2682E/ADM2687E
Preliminary Technical Data
DC CORRECTNESS AND MAGNETIC FIELD IMMUNITY
MAXIMUM ALLOWABLE MAGNETIC FLUX
DENSITY (kGauss)
100
The digital signals transmit across the isolation barrier using
iCoupler technology. This technique uses chip-scale transformer
windings to couple the digital signals magnetically from one
side of the barrier to the other. Digital inputs are encoded into
waveforms that are capable of exciting the primary transformer
winding. At the secondary winding, the induced waveforms are
decoded into the binary value that was originally transmitted.
The 3.3 V operating condition of the ADM2682E/ADM2687E
is examined because it represents the most susceptible mode of
operation. The pulses at the transformer output have an amplitude
of >1.0 V. The decoder has a sensing threshold of about 0.5 V,
thus establishing a 0.5 V margin in which induced voltages can
be tolerated. The voltage induced across the receiving coil is
given by
0.1
1M
10k
10M
100k
MAGNETIC FIELD FREQUENCY (Hz)
100M
08111-019
0.001
1k
Figure 33. Maximum Allowable External Magnetic Flux Density
For example, at a magnetic field frequency of 1 MHz, the
maximum allowable magnetic field of 0.2 kgauss induces a
voltage of 0.25 V at the receiving coil. This is about 50% of the
sensing threshold and does not cause a faulty output transition.
Similarly, if such an event occurs during a transmitted pulse
(and is of the worst-case polarity), it reduces the received pulse
from >1.0 V to 0.75 V, which is still well above the 0.5 V sensing
threshold of the decoder.
The preceding magnetic flux density values correspond
to specific current magnitudes at given distances from the
ADM2682E/ADM2687E transformers. Figure 34 expresses
these allowable current magnitudes as a function of frequency
for selected distances. As shown in Figure 34, the ADM2682E/
ADM2687E are extremely immune and can be affected only by
extremely large currents operated at high frequency very close
to the component. For the 1 MHz example, a 0.5 kA current must
be placed 5 mm away from the ADM2682E/ADM2687E to affect
component operation.
1k
V = (−dβ/dt)Σπrn2; n = 1, 2, … , N
where:
β is magnetic flux density (gauss).
N is the number of turns in the receiving coil.
rn is the radius of the nth turn in the receiving coil (cm).
Given the geometry of the receiving coil in the ADM2682E/
ADM2687E and an imposed requirement that the induced
voltage be, at most, 50% of the 0.5 V margin at the decoder, a
maximum allowable magnetic field is calculated as shown in
Figure 33.
DISTANCE = 1m
100
10
DISTANCE = 100mm
1
DISTANCE = 5mm
0.1
0.01
1k
10k
100k
1M
10M
100M
MAGNETIC FIELD FREQUENCY (Hz)
08111-020
This situation should occur in the ADM2682E/ADM2687E devices
only during power-up and power-down operations. The limitation
on the ADM2682E/ADM2687E magnetic field immunity is set
by the condition in which induced voltage in the transformer
receiving coil is sufficiently large to either falsely set or reset the
decoder. The following analysis defines the conditions under
which this can occur.
1
0.01
MAXIMUM ALLOWABLE CURRENT (kA)
Positive and negative logic transitions at the isolator input cause
narrow (~1 ns) pulses to be sent to the decoder via the transformer.
The decoder is bistable and is, therefore, either set or reset by
the pulses, indicating input logic transitions. In the absence of
logic transitions at the input for more than 1 µs, periodic sets of
refresh pulses indicative of the correct input state are sent to
ensure dc correctness at the output. If the decoder receives no
internal pulses of more than approximately 5 μs, the input side
is assumed to be unpowered or nonfunctional, in which case,
the isolator output is forced to a default state by the watchdog
timer circuit.
10
Figure 34. Maximum Allowable Current for Various Current-toADM2682E/ADM2687E Spacings
Note that in combinations of strong magnetic field and high
frequency, any loops formed by printed circuit board (PCB)
traces can induce error voltages sufficiently large to trigger the
thresholds of succeeding circuitry. Take care in the layout of
such traces to avoid this possibility.
Rev. PrE | Page 16 of 20
Preliminary Technical Data
ADM2682E/ADM2687E
APPLICATIONS INFORMATION
PCB LAYOUT
The ADM2682E/ADM2687E isolated RS-422/RS-485 transceiver
contains an isoPower integrated dc-to-dc converter, requiring
no external interface circuitry for the logic interfaces. Power
supply bypassing is required at the input and output supply pins
(see Figure 35). The power supply section of the ADM2682E/
ADM2687E uses an 180 MHz oscillator frequency to pass power
efficiently through its chip-scale transformers. In addition, the
normal operation of the data section of the iCoupler introduces
switching transients on the power supply pins.
Bypass capacitors are required for several operating frequencies.
Noise suppression requires a low inductance, high frequency
capacitor, whereas ripple suppression and proper regulation
require a large value capacitor. These capacitors are connected
between Pin 1 (GND1) and Pin 2 (VCC) and Pin 7 (VCC) and
Pin 8 (GND1) for VCC. The VISOIN and VISOOUT capacitors are
connected between Pin 9 (GND2) and Pin 10 (VISOOUT) and
Pin 15 (VISOIN) and Pin 16 (GND2). To suppress noise and reduce
ripple, a parallel combination of at least two capacitors is required
with the smaller of the two capacitors located closest to the device.
The recommended capacitor values are 0.1 µF and 10 µF for
VISOOUT at Pin 9 and 10 and VCC at Pin 7 and 8. Capacitor values
of 0.01 µF and 0.1 µF are recommended for VISOIN at Pin 15 and
16 and VCC at Pin 1 and 2. The recommended best practice is to
use a very low inductance ceramic capacitor, or its equivalent,
for the smaller value capacitors. The total lead length between
both ends of the capacitor and the input power supply pin
should not exceed 10 mm.
10nF
100nF
10nF
100nF
GND1
1
16
VCC
2
15
RxD
3
14
RE
4
DE
5
TxD
VCC
GND1
10µF
100nF
GND2
VISOIN
A
13
B
12
Z
6
11
Y
7
10
8
9
ADM2682E
ADM2687E
VISOOUT
GND2
10µF
100nF
Figure 35. Recommended PCB Layout
In applications involving high common-mode transients, ensure
that board coupling across the isolation barrier is minimized.
Furthermore, design the board layout such that any coupling
that does occur equally affects all pins on a given component
side. Failure to ensure this can cause voltage differentials between
pins exceeding the absolute maximum ratings for the device,
thereby leading to latch-up and/or permanent damage.
The ADM2682E/ADM2687E dissipate approximately 650 mW
of power when fully loaded. Because it is not possible to apply
a heat sink to an isolation device, the devices primarily depend
on heat dissipation into the PCB through the GND pins. If the
devices are used at high ambient temperatures, provide a thermal
path from the GND pins to the PCB ground plane. The board
layout in Figure 35 shows enlarged pads for Pin 1, Pin 8, Pin 9,
and Pin 16. Implement multiple vias from the pad to the ground
plane to reduce the temperature inside the chip significantly. The
dimensions of the expanded pads are at the discretion of the
designer and dependent on the available board space.
EMI CONSIDERATIONS
The dc-to-dc converter section of the ADM2682E/ADM2687E
components must, of necessity, operate at very high frequency
to allow efficient power transfer through the small transformers.
This creates high frequency currents that can propagate in circuit
board ground and power planes, causing edge and dipole radiation.
Grounded enclosures are recommended for applications that use
these devices. If grounded enclosures are not possible, good RF
design practices should be followed in the layout of the PCB.
See Application Note AN-0971, Control of Radiated Emissions
with isoPower Devices, for more information.
INSULATION LIFETIME
All insulation structures eventually break down when subjected to
voltage stress over a sufficiently long period. The rate of insulation
degradation is dependent on the characteristics of the voltage
waveform applied across the insulation. Analog Devices conducts
an extensive set of evaluations to determine the lifetime of the
insulation structure within the ADM2682E/ADM2687E.
Accelerated life testing is performed using voltage levels higher
than the rated continuous working voltage. Acceleration factors for
several operating conditions are determined, allowing calculation
of the time to failure at the working voltage of interest. The values
shown in Table 9 summarize the peak voltages for 50 years of
service life in several operating conditions. In many cases, the
working voltage approved by agency testing is higher than the
50-year service life voltage. Operation at working voltages higher
than the service life voltage listed leads to premature insulation
failure.
The insulation lifetime of the ADM2682E/ADM2687E depends
on the voltage waveform type imposed across the isolation barrier.
The iCoupler insulation structure degrades at different rates,
depending on whether the waveform is bipolar ac, unipolar ac,
or dc. Figure 36, Figure 37, and Figure 38 illustrate these different
isolation voltage waveforms.
Bipolar ac voltage is the most stringent environment. A 50-year
operating lifetime under the bipolar ac condition determines
the Analog Devices recommended maximum working voltage.
In the case of unipolar ac or dc voltage, the stress on the insulation
is significantly lower. This allows operation at higher working
voltages while still achieving a 50-year service life. The working
Rev. PrE | Page 17 of 20
ADM2682E/ADM2687E
Preliminary Technical Data
voltages listed in Table 9 can be applied while maintaining the
50-year minimum lifetime, provided the voltage conforms to either
the unipolar ac or dc voltage cases. Any crossinsulation voltage
waveform that does not conform to Figure 37 or Figure 38 should
be treated as a bipolar ac waveform, and its peak voltage should
be limited to the 50-year lifetime voltage value listed in Table 9.
RATED PEAK VOLTAGE
Figure 36. Bipolar AC Waveform
08111-023
RATED PEAK VOLTAGE
0V
An example application of the ADM2682E/ADM2687E for a
full-duplex RS-485 node is shown in the circuit diagram of
Figure 39. Refer to the section PCB Layout for the
recommended placement of the capacitors shown in this circuit
diagram. Note that resistors RT are only included at the nodes
on either end of the bus and depend on the network
configuration.
Figure 40 and Figure 41 show typical applications of the
ADM2682E/ ADM2687E in half duplex and full duplex RS-485
network configurations. Up to 256 transceivers can be connected to
the RS-485 bus. To minimize reflections, terminate the line at the
receiving end in its characteristic impedance, and keep stub
lengths off the main line as short as possible. For half-duplex
operation, this means that both ends of the line must be
terminated because either end can be the receiving end.
08111-021
0V
TYPICAL APPLICATIONS
Figure 37. DC Waveform
0V
NOTES
1. THE VOLTAGE IS SHOWN AS SINUSODIAL FOR ILLUSTRATION
PURPOSES ONLY. IT IS MEANT TO REPRESENT ANY VOLTAGE
WAVEFORM VARYING BETWEEN 0 AND SOME LIMITING VALUE.
THE LIMITING VALUE CAN BE POSITIVE OR NEGATIVE, BUT THE
VOLTAGE CANNOT CROSS 0V.
08111-022
RATED PEAK VOLTAGE
Figure 38. Unipolar AC Waveform
3.3V/5V POWER
SUPPLY
100nF
10µF
100nF
10nF
VCC
VISOOUT
VCC
100nF
10µF
isoPower DC-TO-DC CONVERTER
OSCILLATOR
RECTIFIER
VISOIN
100nF
REGULATOR
DIGITAL ISOLATION iCoupler
TxD
MICROCONTROLLER
AND UART
DE
TRANSCEIVER
ENCODE
DECODE
ENCODE
DECODE
DECODE
ENCODE
D
10nF
Y
Z
A
RxD
RE
R
ADM2682E/ADM2687E
GND1
ISOLATION
BARRIER
GND2
GND1
Figure 39. Example Circuit Diagram Using the ADM2682E/ADM2687E
Rev. PrE | Page 18 of 20
B
RT
Preliminary Technical Data
ADM2682E/ADM2687E
MAXIMUM NUMBER OF TRANSCEIVERS ON BUS = 256
ADM2682E/
ADM2687E
RxD
R
A
A
B
B
ADM2682E/
ADM2687E
RxD
R
RE
RE
RT
RT
DE
TxD
Z
D
DE
Z
Y
D
Y
A
B
Z
Y
A
B
R
Z
TxD
Y
R
D
ADM2682E/
ADM2687E
RxD RE
D
ADM2682E/
ADM2687E
DE TxD
RxD RE
DE TxD
NOTES
1. RT IS EQUAL TO THE CHARACTERISTIC IMPEDANCE OF THE CABLE.
2. ISOLATION NOT SHOWN.
Figure 40. ADM2682E/ADM2687E Typical Half Duplex RS-485 Network
MAXIMUM NUMBER OF NODES = 256
MASTER
SLAVE
A
R
RxD
B
Y
D
RT
RE
DE
Z
DE
TxD
TxD
Z
D
B
RT
Y
A
ADM2682E/
ADM2687E
RE
R
ADM2682E/
ADM2687E
A
B
Z
Y
A
B
Z
Y
SLAVE
SLAVE
R
R
D
D
ADM2682E/
ADM2687E
ADM2682E/
ADM2687E
RxD RE
DE TxD
RxD RE
DE TxD
NOTES
1. RT IS EQUAL TO THE CHARACTERISTIC IMPEDANCE OF THE CABLE.
2. ISOLATION NOT SHOWN.
Figure 41. ADM2682E/ADM2687E Typical Full Duplex RS-485 Network
Rev. PrE | Page 19 of 20
RxD
ADM2682E/ADM2687E
Preliminary Technical Data
OUTLINE DIMENSIONS
13.00 (0.5118)
12.60 (0.4961)
9
16
7.60 (0.2992)
7.40 (0.2913)
0.30 (0.0118)
0.10 (0.0039)
COPLANARITY
0.10
8
10.65 (0.4193)
10.00 (0.3937)
2.65 (0.1043)
2.35 (0.0925)
1.27
(0.0500)
BSC
0.51 (0.0201)
0.31 (0.0122)
0.75 (0.0295)
45°
0.25 (0.0098)
8°
0°
SEATING
PLANE
0.33 (0.0130)
0.20 (0.0079)
1.27 (0.0500)
0.40 (0.0157)
COMPLIANT TO JEDEC STANDARDS MS-013-AC
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
10-12-2010-A
1
Figure 42. 16-Lead Standard Small Outline Package with Increased Creepage [SOIC_IC]
Wide Body,
(RI-16)
Dimensions shown in millimeters and (inches)
ORDERING GUIDE
Model 1
ADM2682EBRIZ
ADM2682EBRIZ-RL7
ADM2687EBRIZ
ADM2687EBRIZ-RL7
1
Data Rate (Mbps)
16
16
0.5
0.5
Temperature Range
−40°C to +85°C
−40°C to +85°C
−40°C to +85°C
−40°C to +85°C
Z = RoHS Compliant Part.
©2011 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
PR09927-0-5/11(PrE)
Rev. PrE | Page 20 of 20
Package Description
16-Lead SOIC_IC
16-Lead SOIC_IC
16-Lead SOIC_IC
16-Lead SOIC_IC
Package Option
RI-16
RI-16
RI-16
RI-16