ADM2490EBRWZ-REEL71 [ADI]
High Speed, ESD-Protected, Full-Duplex, iCoupler, Isolated RS-485 Transceiver; 高速， ESD保护，全双工， iCoupler隔离器，隔离式RS -485收发器
| 型号： | ADM2490EBRWZ-REEL71 |
| 厂家： | 
ADI |
| 描述： | High Speed, ESD-Protected, Full-Duplex, iCoupler, Isolated RS-485 Transceiver |
| 文件： | 总16页 (文件大小：549K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
High Speed, ESD-Protected, Full-Duplex,
iCoupler®, Isolated RS-485 Transceiver
ADM2490E
FEATURES
FUNCTIONAL BLOCK DIAGRAM
V
V
DD2
DD1
Isolated, full-duplex RS-485/RS-422 transceiver
8 kV ESD protection on RS-485 input/output pins
16 Mbps data rate
ADM2490E
Complies with ANSI TIA/EIA RS-485-A-1998 and
ISO 8482: 1987(E)
Y
Z
TxD
RxD
Suitable for 5 V or 3 V operation (VDD1
)
High common-mode transient immunity: >25 kV/μs
Receiver has open-circuit, fail-safe design
32 nodes on the bus
A
B
Thermal shutdown protection
Safety and regulatory approvals pending
UL recognition: 5000 V rms isolation voltage
for 1 minute per UL 1577
GND
GND
2
1
Figure 1.
VDE certificate of conformity
DIN EN 60747-5-2 (VDE 0884 Part 2): 2003-01
DIN EN 60950 (VDE 0805): 2001-12; EN 60950: 2000
GENERAL DESCRIPTION
The ADM2490E is an isolated data transceiver with ±± ꢀk EꢁD
protection and is suitable for high speed, full-duplex
VIORM = 848 VPEAK
Operating temperature range: −40°C to +105°C
Wide-body, 16-lead SOIC package
communication on multipoint transmission lines. It is designed
for balanced transmission lines and complies with ANꢁI
TIA/EIA Rꢁ-4±5-A-199± and IꢁO ±4±2: 19±7(E). The device
employs Analog Devices, Inc., iCoupler technology to combine
a 2-channel isolator, a 3-state differential line driver, and a
differential input receiver into a single pacꢀage.
APPLICATIONS
Isolated RS-485/RS-422 interfaces
Industrial field networks
INTERBUS
The differential transmitter outputs and receiver inputs feature
electrostatic discharge circuitry that provides protection to
±± ꢀk using the human body model (HBM). The logic side of
the device can be powered with either a 5 k or a 3 k supply,
whereas the bus side requires an isolated 5 k supply.
Multipoint data transmission systems
The device has current-limiting and thermal shutdown features
to protect against output short circuits and situations where bus
contention could cause excessive power dissipation.
Rev. 0
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 registeredtrademarks arethe property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.461.3113
www.analog.com
©2006 Analog Devices, Inc. All rights reserved.
ADM2490E
TABLE OF CONTENTS
Features .............................................................................................. 1
Test Circuits........................................................................................9
ꢁwitching Characteristics .............................................................. 10
Typical Performance Characteristics ........................................... 11
Circuit Description......................................................................... 13
Electrical Isolation...................................................................... 13
Truth Tables................................................................................. 13
Thermal ꢁhutdown .................................................................... 14
Fail-ꢁafe Receiver Inputs ........................................................... 14
Magnetic Field Immunity.......................................................... 14
Applications Information.............................................................. 15
Isolated Power-ꢁupply Circuit.................................................. 15
PC Board Layout ........................................................................ 15
Outline Dimensions....................................................................... 16
Ordering Guide .......................................................................... 16
Applications....................................................................................... 1
Functional Blocꢀ Diagram .............................................................. 1
General Description......................................................................... 1
Revision History ............................................................................... 2
ꢁpecifications..................................................................................... 3
Timing ꢁpecifications .................................................................. 4
ADM2490E Characteristics............................................................. 5
Pacꢀage Characteristics ............................................................... 5
Regulatory Information (Pending) ............................................ 5
Insulation and ꢁafety-Related ꢁpecifications............................ 5
kDE 0±±4 Insulation Characteristics (Pending)...................... 6
Absolute Maximum Ratings............................................................ 7
EꢁD Caution.................................................................................. 7
Pin Configuration and Functional Descriptions.......................... ±
REVISION HISTORY
10/06—Revision 0: Initial Version
Rev. 0 | Page 2 of 16
ADM2490E
SPECIFICATIONS
All voltages are relative to their respective ground; 2.7 ≤ kDD1 ≤ 5.5 k, 4.5 k ≤ kDD2 ≤ 5.5 k. All minimum/maximum specifications apply
over the entire recommended operation range, unless otherwise noted. All typical specifications are at TA = 25°C, kDD1 = kDD2 = 5.0 k,
unless otherwise noted.
Table 1.
Parameter
Symbol Min
Typ
Max
Unit
Test Conditions
SUPPLY CURRENT
Power-Supply Current, Logic Side
TxD/RxD Data Rate < 2 Mbps
TxD/RxD Data Rate = 16 Mbps
Power-Supply Current, Bus Side
TxD/RxD Data Rate < 2 Mbps
TxD/RxD Data Rate = 16 Mbps
DRIVER
IDD1
IDD1
3.0
6
mA
mA
2.7 V ≤ VDD1 ≤ 5.5 V, unloaded
100 Ω load between Y and Z
IDD2
IDD2
4.0
60
mA
mA
2.7 V ≤ VDD1 ≤ 5.5 V, unloaded
100 Ω load between Y and Z
Differential Outputs
Differential Output Voltage, Loaded
|VOD2
|
2.0
1.5
1.5
5.0
5.0
5.0
0.2
3.0
0.2
200
V
RL = 50 Ω (RS-422),
see Figure 3
RL = 27 Ω (RS-485),
see Figure 3
−7 V ≤ VTEST1 ≤ +12 V,
see Figure 4
RL = 54 Ω or 100 Ω,
see Figure 3
RL = 54 Ω or 100 Ω,
see Figure 3
RL = 54 Ω or 100 Ω,
see Figure 3
V
|VOD4
|
V
∆|VOD| for Complementary Output States
Common-Mode Output Voltage
∆|VOD
|
V
VOC
V
∆|VOC| for Complementary Output States
∆|VOC
|
V
Short-Circuit Output Current
Logic Inputs
IOS
mA
Input Threshold Low
Input Threshold High
TxD Input Current
VILTxD
VIHTRxD
ITxD
0.25 × VDD1
−10
V
V
μA
0.7 × VDD1
+10
+0.01
70
RECEIVER
Differential Inputs
Differential Input Threshold Voltage
Input Voltage Hysteresis
Input Current (A, B)
VTH
VHYS
II
−0.2
+0.2
1.0
V
mV
mA
mA
kΩ
VOC = 0 V
VOC = 12 V
VOC = −7 V
−0.8
12
Line Input Resistance
Logic Outputs
RIN
Output Voltage Low
Output Voltage High
Short Circuit Current
VOLRxD
VOHRxD
0.2
VDD1 − 0.2
0.4
V
V
mA
IORxD = 1.5 mA, VA − VB = −0.2 V
IORxD = −1.5 mA, VA − VB = 0.2 V
VDD1 − 0.3
25
100
COMMON-MODE TRANSIENT IMMUNITY1
kV/μs VCM = 1 kV, transient
magnitude = 800 V
1 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. 0 | Page 3 of 16
ADM2490E
TIMING SPECIFICATIONS
TA = −40°C to +±5°C
Table 2.
Parameter
Symbol
Min
Typ
Max
Unit
Test Conditions
DRIVER
Maximum Data Rate
Propagation Delay
16
Mbps
ns
tPLH, tPHL
tPWD, tPWD
tR, tF
45
60
7
RL = 54 Ω, CL1 = C L2 = 100 pF,
see Figure 6 and Figure 8
RL = 54 Ω, CL1 = CL2 = 100 pF,
see Figure 6 and Figure 8
RL = 54 Ω, CL1 = CL2 = 100 pF,
see Figure 6 and Figure 8
Pulse Width Distortion,
PWD = |tPYLH − tPYHL|, PWD = |tPZLH − tPZHL
Single-Ended Output Rise/Fall Times
ns
ns
|
20
RECEIVER
Propagation Delay
tPLH, tPHL
tPWD
60
10
ns
ns
CL = 15 pF, see Figure 7 and Figure
9
CL = 15 pF, see Figure 7 and Figure
9
Pulse Width Distortion, PWD = |tPLH − tPHL
|
TA = −40°C to +105°C
Table 3.
Parameter
Symbol
Min
Typ
Max
Unit
Test Conditions
DRIVER
Maximum Data Rate
Propagation Delay
10
Mbps
ns
tPYLH, tPYHL
tPZLH, tPZHL
tPWD, tPWD
tR, tF
,
45
60
9
RL = 54 Ω, CL1 = CL2 = 100 pF,
see Figure 6 and Figure 8
RL = 54 Ω, CL1 = CL2 = 100 pF,
see Figure 6 and Figure 8
RL = 54 Ω, CL1 = CL2 = 100 pF,
see Figure 6 and Figure 8
Pulse Width Distortion,
PWD = |tPYLH − tPYHL|, PWD = |tPZLH − tPZHL
Single-Ended Output Rise/Fall Time
ns
ns
|
27
RECEIVER
Propagation Delay
tPLH, tPHL
tPWD
60
10
ns
ns
CL = 15 pF, see Figure 7 and
Figure 9
CL = 15 pF, see Figure 7 and
Figure 9
Pulse Width Distortion, PWD = |tPLH − tPHL
|
Rev. 0 | Page 4 of 16
ADM2490E
ADM2490E CHARACTERISTICS
PACKAGE CHARACTERISTICS
Table 4.
Parameter
Symbol
RI-O
CI-O
Min
Typ
1012
3
Max
Unit
Ω
pF
Test Conditions
Resistance (Input-Output)1
Capacitance (Input-Output)1
Input Capacitance2
f = 1 MHz
CI
4
pF
Input IC Junction-to-Case Thermal Resistance
θJCI
33
°C/W
Thermocouple located at center
of package underside
Output IC Junction-to-Case Thermal Resistance
θJCO
28
°C/W
1 Device considered a 2-terminal device: Pins 1, 2, 3, 4, 5, 6, 7, and 8 are shorted together and Pins 9, 10, 11, 12, 13, 14, 15, and 16 are shorted together.
2 Input capacitance is from any input data pin to ground.
REGULATORY INFORMATION (PENDING)
Table 5.
UL
VDE
To be recognized under 1577 component recognition program: 1 To be certified according to DIN EN 60747-5-2 (VDE 0884 Part 2): 2003-01: 2
5000 V rms isolation voltage
Basic insulation, 848 V peak
Complies with DIN EN 60747-5-2 (VDE 0884 Part 2): 2003-01,
DIN EN 60950 (VDE 0805): 2001-12; EN 60950: 2000, reinforced
insulation, 560 V peak
1 In accordance with UL1577, each ADM2490E is proof tested by applying an insulation test voltage ≥ 6000 V rms for 1 second (current leakage detection limit = 10 μA).
2 In accordance with DIN EN 60747-5-2, each ADM2490E is proof tested by applying an insulation test voltage ≥ 1590 V peak for 1 second (partial discharge detection
limit = 5 pC).
INSULATION AND SAFETY-RELATED SPECIFICATIONS
Table 6.
Parameter
Symbol
Value
5000
7.45
Unit
Conditions
Rated Dielectric Insulation Voltage
Minimum External Air Gap (Clearance)
V rms
mm min
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.
L(I01)
L(I02)
Minimum External Tracking (Creepage)
8.1
mm min
Minimum Internal Gap (Internal Clearance)
Tracking Resistance (Comparative Tracking Index) CTI
Isolation Group
0.017
>175
IIIa
mm min
V
Insulation distance through insulation.
DIN IEC 112/VDE 0303 Part 1.
Material Group (DIN VDE 0110, 1/89).
Rev. 0 | Page 5 of 16
ADM2490E
VDE 0884 INSULATION CHARACTERISTICS (PENDING)
This isolator is suitable for basic electrical isolation only within the safety limit data. Maintenance of the safety data must be ensured by
means of protective circuits.
An asterisꢀ (*) on a pacꢀage denotes kDE 0±±4 approval for ±4± k peaꢀ worꢀing voltage.
Table 7.
Description
Symbol
Characteristic
Unit
Installation Classification per DIN VDE 0110 for Rated Mains Voltage
≤300 V rms
≤450 V rms
≤600 V rms
Climatic Classification
Pollution Degree (DIN VDE 0110, see Table 1)
Maximum Working Insulation Voltage
Input-to-Output Test Voltage, Method b1
VIORM × 1.875 = VPR, 100% Production Tested, tm = 1 sec, Partial Discharge < 5 pC
Input-to-Output Test Voltage, Method a
(After Environmental Tests, Subgroup 1)
VIORM × 1.6 = VPR, tm = 60 sec, Partial Discharge < 5 pC
(After Input and/or Safety Test, Subgroup 2/3)
VIORM × 1.2 = VPR, tm = 60 sec, Partial Discharge < 5 pC
Highest Allowable Overvoltage
I to IV
I to II
I to II
40/105/21
2
VIORM
VPR
848
1590
VPEAK
VPEAK
1357
1018
6000
VPEAK
VPEAK
VPEAK
VPR
VTR
(Transient Overvoltage, tTR = 10 sec)
Safety-Limiting Values
(Maximum Value Allowed in the Event of a Failure; see Figure 16)
Case Temperature
Input Current
Output Current
TS
150
265
335
>109
°C
IS, INPUT
IS, OUTPUT
RS
mA
mA
Ω
Insulation Resistance at TS, VIO = 500 V
Rev. 0 | Page 6 of 16
ADM2490E
ABSOLUTE MAXIMUM RATINGS
TA = 25°C, unless otherwise noted. Each voltage is relative to its
respective ground.
ꢁtresses 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.
Table 8.
Parameter
Rating
Storage Temperature
Ambient Operating Temperature
VDD1
−55°C to +150°C
−40°C to +105°C
−0.5 V to +7 V
−0.5 V to +6 V
−0.5 V to VDD1 + 0.5 V
−9 V to +14 V
−0.5 V to VDD1 + 0.5 V
35 mA
Absolute maximum ratings apply individually only, not in
combination.
VDD2
Logic Input Voltages
Bus Terminal Voltages
Logic Output Voltages
Average Output Current, per Pin
ESD CAUTION
ESD (Human Body Model) on A, B, Y,
and Z pins
8 kV
θJA Thermal Impedance
73°C/W
Rev. 0 | Page 7 of 16
ADM2490E
PIN CONFIGURATION AND FUNCTIONAL DESCRIPTIONS
V
1
2
3
4
5
6
7
8
16
V
DD1
DD2
GND
15 GND
1
2
RxD
NC
14
13
A
B
ADM2490E
TOP VIEW
(Not to Scale)
GND
12 NC
1
TxD
NC
11
10
9
Z
Y
GND
GND
1
2
NC = NO CONNECT
Figure 2. ADM2490E Pin Configuration
Table 9. Pin Function Descriptions
Pin No.
Mnemonic
Description
1
VDD1
Power Supply (logic side). Decoupling capacitor to GND1 required; capacitor value should be between
0.01 μF and 0.1 μF.
2, 5, 8
3
4, 7, 12
6
GND1
RxD
NC
Ground (logic side).
Receiver Output.
No Connect. These pins must be left floating.
Transmit Data.
TxD
9, 15
16
GND2
VDD2
Ground (bus side).
Power Supply (bus side). Decoupling capacitor to GND2 required; capacitor value should be between
0.01 μF and 0.1 μF.
11
10
13
14
Z
Y
B
A
Driver Inverting Output.
Driver Noninverting Output.
Receiver Inverting Input.
Receiver Noninverting Input.
Rev. 0 | Page 8 of 16
ADM2490E
TEST CIRCUITS
R
R
L
C
C
Y
Z
L1
V
OD
R
LDIFF
L
V
OC
L2
Figure 3. Driver Voltage Measurement
Figure 6. Driver Propagation Delay
375Ω
A
V
V
TEST
OD3
60Ω
V
OUT
B
C
L
375Ω
Figure 4. Driver Voltage Measurement
Figure 7. Receiver Propagation Delay
V
DD2
V
V
DD2
DD1
220Ω
100Ω
220Ω
Y
Z
TxD
RxD
A
B
GND
GND
2
1
GND
2
Figure 5. Supply-Current Measurement Test Circuit, See Figure 10 and Figure 11
Rev. 0 | Page 9 of 16
ADM2490E
SWITCHING CHARACTERISTICS
3V
1.5V
1.5V
0V
Z
tPLH
tPHL
A, B
0V
0V
1/2VO
VO
Y
tPLH
tPHL
tPWD = |tPLH
– tPHL|
VOH
V
OH
90% POINT
90% POINT
RO
1.5V
1.5V
A, B
10% POINT
10% POINT
VOL
V
OL
tR
tF
Figure 8. Driver Propagation Delay, Rise/Fall Timing
Figure 9. Receiver Propagation Delay
Rev. 0 | Page 10 of 16
ADM2490E
TYPICAL PERFORMANCE CHARACTERISTICS
60
50
40
30
20
10
0
3.00
2.95
tPLH
tPHL
2.90
NO LOAD
100 LOAD
220-100-220 LOAD
2.85
2.80
2.75
2.70
–40
–20
0
20
40
60
80
100
–40
–20
0
20
40
60
80
100
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 13. Receiver Propagation Delay vs. Temperature
Figure 10. IDD1 Supply Current vs. Temperature (See Figure 5)
70
60
TxD
220-100-220 LOAD
50
1
40
100 LOAD
Y AND Z OUTPUTS
RxD
30
20
2
4
NO LOAD
10
0
–40
–20
0
20
40
60
80
100
CH1 2V
CH3 2V
CH2 2V
CH4 2V
M20ns
44.2%
A CH2
2.84V
TEMPERATURE (°C)
T
Figure 11. IDD2 Supply Current vs. Temperature (See Figure 5)
Figure 14. Driver/Receiver Propagation Delay, Low to High
(RLDIFF = 54 Ω, CL1 = CL2 = 100 pF)
60
TPZHL
TPYLH
TPZLH
TPYHL
50
40
30
20
10
0
TxD
1
Y AND Z OUTPUTS
2
4
RxD
–40
–20
0
20
40
60
80
100
CH1 2V
CH3 2V
CH2 2V
CH4 2V
M20ns
44.2%
A CH2
2.84V
TEMPERATURE (°C)
T
Figure 12. Driver Propagation Delay vs. Temperature
Figure 15. Driver/Receiver Propagation Delay, High to Low
(RLDIFF = 54 Ω, CL1 = CL2 = 100 pF)
Rev. 0 | Page 11 of 16
ADM2490E
4.77
4.76
4.75
4.74
4.73
4.72
4.71
4.70
4.69
4.68
4.67
4.66
350
300
250
200
150
100
50
SIDE 2
SIDE 1
0
0
–40
–20
0
20
40
60
80
100
50
100
CASE TEMPERATURE (°C)
150
200
TEMPERATURE (°C)
Figure 16. Thermal Derating Curve, Dependence of Safety-Limiting
Values with Case Temperature per VDE 0884
Figure 19. Receiver Output High Voltage vs. Temperature,
IRxD = −4 mA
0
–2
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0
–4
–6
–8
–10
–12
–14
4.0
4.2
4.4
4.6
4.8
5.0
–40
–20
0
20
40
60
80
100
VOLTAGE (V)
TEMPERATURE (°C)
Figure 17. Output Current vs. Receiver Output High Voltage
Figure 20. Receiver Output Low Voltage vs. Temperature,
RxD = –4 mA
I
16
14
12
10
8
6
4
2
0
0
0.2
0.4
0.6
0.8
1.0
1.2
VOLTAGE (V)
Figure 18. Output Current vs. Receiver Output Low Voltage
Rev. 0 | Page 12 of 16
ADM2490E
CIRCUIT DESCRIPTION
ELECTRICAL ISOLATION
TRUTH TABLES
The truth tables in this section use the abbreviations shown in
Table 10.
In the ADM2490E, electrical isolation is implemented on the
logic side of the interface. Therefore, the part has two main
sections: a digital isolation section and a transceiver section
(see Figure 21). The driver input signal, which is applied to the
TxD pin and referenced to logic ground (GND1), is coupled
across an isolation barrier to appear at the transceiver section
referenced to isolated ground (GND2). ꢁimilarly, the receiver
input, which is referenced to isolated ground in the transceiver
section, is coupled across the isolation barrier to appear at the
RxD pin referenced to logic ground.
Table 10. Truth Table Abbreviations
Abbreviation Description
H
I
L
X
High level
Indeterminate
Low level
Irrelevant
Table 11. Transmitting
iCoupler Technology
Supply Status
Input
TxD
H
Outputs
The digital signals are transmitted 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.
VDD1
On
On
VDD2
On
On
Y
H
L
Z
L
H
L
Table 12. Receiving
Supply Status
Inputs
A − B (V)
>0.2
Output
VDD1
On
On
On
On
On
Off
Off
VDD2
On
On
On
On
Off
On
Off
RxD
H
L
<−0.2
−0.2 < A − B < +0.2
Inputs open
I
H
H
H
L
X
X
X
V
V
DD1
DD2
ISOLATION
BARRIER
Y
Z
TxD
RxD
D
ENCODE
DECODE
DECODE
A
B
ENCODE
R
TRANSCEIVER
DIGITAL ISOLATION
GND
GND
2
1
Figure 21. ADM2490E Digital Isolation and Transceiver Sections
Rev. 0 | Page 13 of 16
ADM2490E
100
10
THERMAL SHUTDOWN
The ADM2490E contains thermal-shutdown circuitry that protects
the part from excessive power dissipation during fault conditions.
ꢁhorting 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 re-enabled at a temperature of 140°C.
1
0.1
0.01
FAIL-SAFE RECEIVER INPUTS
The receiver inputs include a fail-safe feature that guarantees a
logic high on the RxD pin when the A and B inputs are floating
or open-circuited.
0.001
1k
10k
100k
1M
10M
100M
MAGNETIC FIELD FREQUENCY (Hz)
Figure 22. Maximum Allowable External Magnetic Flux Density
MAGNETIC FIELD IMMUNITY
For example, at a magnetic field frequency of 1 MHz, the
maximum allowable magnetic field of 0.2 ꢀGauss induces a
voltage of 0.25 k at the receiving coil. This is about 50% of the
sensing threshold and does not cause a faulty output transition.
ꢁimilarly, if such an event occurs during a transmitted pulse and
is the worst-case polarity, it reduces the received pulse from
>1.0 k to 0.75 k—still well above the 0.5 k sensing threshold of
the decoder.
Because iCouplers use a coreless technology, no magnetic
components are present and the problem of magnetic saturation
of the core material does not exist. Therefore, iCouplers have
essentially infinite dc field immunity. The following analysis
defines the conditions under which this may occur. The 3 k
operating condition of the ADM2409E is examined because it
represents the most susceptible mode of operation.
The limitation on the ac magnetic field immunity of the
iCoupler is set by the condition that induced an error voltage in
the receiving coil (the bottom coil in this case) that was large to
either falsely set or reset the decoder. The voltage induced
across the bottom coil is given by
Figure 23 shows the magnetic flux density values in terms of
more familiar quantities, such as maximum allowable current
flow, at given distances away from the ADM2490E transformers.
1000
DISTANCE = 1m
− dβ
⎛
⎜
⎝
⎞
⎟
⎠
; n =1, 2, . . . , N
V =
πr2
100
∑
n
dt
DISTANCE = 5mm
10
where, if the pulses at the transformer output are greater than
1.0 k in amplitude:
β = magnetic flux density (gauss).
DISTANCE = 100mm
1
N = number of turns in receiving coil.
rn = radius of nth turn in receiving coil (cm).
0.1
The decoder has a sensing threshold of about 0.5 k; therefore,
there is a 0.5 k margin in which induced voltages can be
tolerated.
0.01
1k
10k
100k
1M
10M
100M
Given the geometry of the receiving coil and an imposed
requirement that the induced voltage is, at most, 50% of the
0.5 k margin at the decoder, a maximum allowable magnetic
field is calculated, as shown in Figure 22.
MAGNETIC FIELD FREQUENCY (Hz)
Figure 23. Maximum Allowable Current for
Various Current-to-ADM2490E Spacings
With combinations of strong magnetic field and high frequency,
any loops formed by printed circuit board traces could induce
error voltages large enough to trigger the thresholds of succeeding
circuitry. Care should be taꢀen in the layout of such traces to
avoid this possibility.
Rev. 0 | Page 14 of 16
ADM2490E
APPLICATIONS INFORMATION
kDD2. The capacitor value should be between 0.01 μF and 0.1 μF.
The total lead length between both ends of the capacitor and
the input power-supply pin should not exceed 20 mm.
Bypassing between Pins 1 and ± and between Pins 9 and 16
should also be considered unless the ground pair on each
pacꢀage side is connected close to the pacꢀage.
ISOLATED POWER-SUPPLY CIRCUIT
The ADM2490E requires isolated power capable of 5 k at up to
approximately 75 mA (this current is dependant on the data
rate and termination resistors used) to be supplied between the
kDD2 and the GND2 pins. A transformer-driver circuit with a
center-tapped transformer and LDO can be used to generate the
isolated 5 k supply, as shown in Figure 25. The center-tapped
transformer provides electrical isolation of the 5 k power
supply. The primary winding of the transformer is excited with
a pair of square waveforms that are 1±0° out of phase with each
other. A pair of ꢁchottꢀy diodes and a smoothing capacitor are
used to create a rectified signal from the secondary winding.
The ADP667 linear voltage regulator provides a regulated
power supply to the bus-side circuitry (kDD2) of the
ADM2490E.
V
V
DD2
DD1
GND
GND
1
2
RxD
NC
GND
1
TxD
NC
A
B
NC
Z
Y
ADM2490E
GND
GND
1
2
NC = NO CONNECT
Figure 24. Recommended Printed Circuit Board Layout
In applications involving high common-mode transients, care
should be taꢀen to ensure that board coupling across the isola-
tion barrier is minimized. Furthermore, the board layout should
be designed such that any coupling that does occur equally affects
all pins on a given component side. Failure to ensure this could
cause voltage differentials between pins exceeding the absolute
maximum ratings of the device, thereby leading to latch-up or
permanent damage.
PC BOARD LAYOUT
The ADM2490E isolated Rꢁ-4±5 transceiver requires no
external interface circuitry for the logic interfaces. Power-
supply bypassing is required at the input and output supply pins
(Figure 24). Bypass capacitors are conveniently connected
between Pins 1 and 2 for kDD1 and between Pins 15 and 16 for
ISOLATION
BARRIER
V
CC
SD103C
5V
IN
OUT
V
22µF
10µF
CC
ADP667
TRANSFORMER
DRIVER
SET GND SHDN
78253
SD103C
V
CC
V
V
DD2
DD1
ADM2490E
GND
GND
2
1
Figure 25. Isolated Power-Supply Circuit
Rev. 0 | Page 15 of 16
ADM2490E
OUTLINE DIMENSIONS
10.50 (0.4134)
10.10 (0.3976)
16
1
9
8
7.60 (0.2992)
7.40 (0.2913)
10.65 (0.4193)
10.00 (0.3937)
0.50 (0.0197)
0.25 (0.
0098)
1.27 (0.0500)
BSC
45°
2.65 (0.1043)
2.35 (0.0925)
0.30 (0.0118)
0.10 (0.0039)
8°
0°
COPLANARITY
0.10
SEATING
PLANE
0.51 (0.0201)
0.31 (0.0122)
1.27 (0.0500)
0.40 (0.0157)
0.33 (0.0130)
0.20 (0.0079)
COMPLIANT TO JEDEC STANDARDS MS-013-AA
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.
Figure 26. 16-Lead Standard Small Outline Package [SOIC_W]
Wide Body
(RW-16)
Dimensions shown in millimeters and (inches)
ORDERING GUIDE
Model
ADM2490EBRWZ1
ADM2490EBRWZ–REEL71
Temperature Range
−40°C to +105°C
−40°C to +105°C
Package Description
Package Option
RW-16
RW-16
16-Lead Wide Body SOIC_W
16-Lead Wide Body SOIC_W
1 Z = Pb-free part.
©2006 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D05889-0-10/06(0)
Rev. 0 | Page 16 of 16
相关型号：
ADM2491EBRWZ-REEL7
High Speed, ESD-Protected, Half-/Full-Duplex Coupler Isolated RS-485 Transceiver
ADI
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