ADM2490E High Speed ESD Protected Full-Duplex iCoupler Isolated RS-485 Transceiver Preliminary Data Sheet (Rev. PrI)
High Speed ESD Protected Full-Duplex
iCoupler
Isolated RS-485 Transceiver
Preliminary Technical Data
ADM2490E
Rev. PrI
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
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Tel: 781.329.4700
www.analog.com
Fax: 781.326.8703
2005 Analog Devices, Inc. All rights reserved.
FEATURES
Isolated Full Duplex RS-485/RS-422 transceiver
8kV ESD protection on RS-485 I/O pins
16Mbps Data Rate
Complies with ANSI TIA/EIA RS-485-A-1998 and
ISO 8482:1987(E)
Suitable for 5 V or 3 V operation (V
DD1
)
High common mode transient immunity: >25kV/ s
Receiver open-circuit fail-safe design
Thermal shutdown protection
Safety and regulatory approvals pending
UL recognition: 2500 V rms for 1 minute per UL 1577
CSA component acceptance notice #5A
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
V
IORM
= 560 V peak
Operating Temperature Range: -40 to 105C
Wide body 16-lead SOIC package
APPLICATIONS
Isolated RS-485/RS-422 Interfaces
Industrial field networks
INTERBUS
Multipoint data transmission systems
FUNCTIONAL BLOCK DIAGRAM
Figure 1. Functional Block Diagram
GENERAL DESCRIPTION
The ADM2490E is an isolated data transceiver with 8kV ESD
protection suitable for high-speed full-duplex communication
on multipoint transmission lines. It is designed for balanced
transmission lines and complies with ANSI TIA/EIA RS-485-A
and ISO 8482:1987(E). The device employs Analog Devices'
iCoupler technology to combine a 2-channel isolator, a 3-state
differential line driver and a differential input receiver into a
single package.
The differential transmitter outputs and receiver inputs feature
electrostatic discharge circuitry which provides protection to
8kV using the Human Body Model (HBM). The logic side of
the device can be powered with either a 5 V or a 3 V supply
while an isolated 5V supply is required for the bus side.
The device has current-limiting and thermal shutdown features
to protect against output short circuits and situations where bus
contention might cause excessive power dissipation.
ADM2490E
Preliminary Technical Data
Rev. PrI | Page 2 of 13
ADM2490E--SPECIFICATIONS
Table 1. All voltages are relative to their respective ground; 2.7 V
DD1
5.5 V, 4.5 V V
DD2
5.5 V. All min/max specifications
apply over the entire recommended operation range unless otherwise noted. All typical specifications are at T
A
= 25C,
V
DD1
=V
DD2
=5.0 V unless otherwise noted.
Parameter Symbol
Min
Typ
Max
Unit
Test
Conditions
SUPPLY
CURRENT
Power Supply Current Logic Side
TxD/RxD Data Rate < 2 Mbps
I
DD1
3.0
mA
2.7V
V
DD1
5.5V
Bus
Side
Power Supply Current Bus Side
I
DD2
4.0
mA
Unloaded
DRIVER
Differential
Outputs
Differential Output Voltage, Loaded
|V
OD2
| 2.0 5.0
V
R=50
, (RS-422), Fig. 3
1.5
5.0
V
R = 27 (RS-485), Fig 3
|V
OD4
| 1.5 5.0
V
-7V
V
test1
12V, Fig. 4
|V
OD
| for Complementary Output States
|V
OD
|
0.2
V
R
L
=54
or 100, Fig. 3
Common Mode Output Voltage
V
OC
3.0
V
R
L
=54
or 100, Fig. 3
|V
OC
| for Complementary Output States
|V
OC
|
0.2
V
R
L
=54
or 100, Fig. 3
Short Circuit Output Current
I
OS
200
mA
Logic
Inputs
Input Threshold Low
V
ILTxD
0.25V
DD1
V
Input Threshold High
V
IHTRxD
0.7V
DD1
V
TxD Input Current
I
TxD
-10
0.01
10
A
RECEIVER
Differential
Inputs
Differential Input Threshold Voltage
V
TH
-0.2
0.2
V
Input Voltage Hysteresis
V
HYS
70
mV
V
OC
=0V
Input Current (A, B)
I
I
1.0
mA
V
OC
=12V
-0.8
mA
V
OC
=-7V
Line Input Resistance
R
IN
12
k
Logic
Outputs
Output Voltage Low
V
OLRxD
0.0
0.4
V
I
ORxD
=4mA, V
A
-V
B
=-0.2V
Output Voltage High
V
OHRxD
V
DD1
- 0.3
V
DD1
-0.2 V I
ORxD
=-1.5 mA, V
A
-V
B
=0.2V
Preliminary Technical Data
ADM2490E
Rev. PrI | Page 3 of 13
TIMING SPECIFICATIONS
(T
A
= -40C to +85C)
Parameter Symbol
Min.
Typ
Max
Unit
Test
Conditions
DRIVER
Maximum Data Rate
16
Mbps
Propagation Delay
t
PLH
, t
PHL
45 60
ns
R
L
=54
, C
L1
=C
L2
=100pF, Fig. 5
Pulse Width Distortion, PWD=|t
PYLH
-t
PYHL
|,
PWD=|t
PZLH
-t
PZHL
|
t
PWD
,
t
PWD
7
ns
R
L
=54
, C
L1
=C
L2
=100pF, Fig. 5
Single Ended Output Rise/Fall Time
t
R
, t
F
20
ns
R
L
=54
, C
L1
=C
L2
=100pF, Fig. 5
RECEIVER
Propagation Delay
t
PLH
, t
PHL
,
60
ns
C
L
=15pF, Fig. 6
Pulse Width Distortion, PWD=|t
PLH
-t
PHL
|,
t
PWD
,
10
ns
C
L
=15pF, Fig. 6
TIMING SPECIFICATIONS
(T
A
= -40C to +105C)
Parameter Symbol
Min.
Typ
Max
Unit
Test
Conditions
DRIVER
Maximum Data Rate
10
Mbps
Propagation Delay
t
PYLH
, t
PYHL
,
t
PZLH
, t
PZHL
45 60
ns
R
L
=54
, C
L1
=C
L2
=100pF, Fig. 5
Pulse Width Distortion, PWD=|t
PYLH
-t
PYHL
|,
PWD=|t
PZLH
-t
PZHL
|
t
PWD
,
t
PWD
9
ns
R
L
=54
, C
L1
=C
L2
=100pF, Fig. 5
Single Ended Output Rise/Fall Time
t
R
, t
F
35
ns
R
L
=54
, C
L1
=C
L2
=100pF, Fig. 5
RECEIVER
Propagation Delay
t
PLH
, t
PHL
,
60
ns
C
L
=15pF, Fig. 6
Pulse Width Distortion, PWD=|t
PLH
-t
PHL
|,
t
PWD
,
10
ns
C
L
=15pF, Fig. 6
ABSOLUTE MAXIMUM RATINGS
Table 2. Ambient temperature = 25 C unless otherwise noted.
All voltages are relative to their respective ground.
Parameter Rating
Storage temperature
-55C to 150C
Ambient operating temperature
-40C to 105C
V
DD1
-0.5 V to +7 V
V
DD2
-0.5 V to +6 V
Logic input voltages
-0.5V to V
DD1
+ 0.5V
Bus terminal voltages
-9V to 14V
Logic output voltages
-0.5V to V
DD1
+ 0.5V
Average output current, per pin
35mA
ESD (human body model) on
A,B,Y and Z pins
8kV
JA
Thermal Impedance
73C/W
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 rating conditions for extended periods may affect
device reliability. Absolute maximum ratings apply individually
only, not in combination.
ADM2490E
Preliminary Technical Data
Rev. PrI | Page 4 of 13
ADM2490E CHARACTERISTICS
PACKAGE CHARACTERISTICS
Table 3.
Parameter Symbol
Min
Typ
Max
Unit
Test
Conditions
Resistance (Input-Output)
1
R
I-O
10
12
Capacitance (Input-Output)
1
C
I-O
3
pF
f = 1 MHz
Input Capacitance
2
C
I
4
pF
Input IC Junction-to-Case Thermal Resistance
JCI
33
C/W
Output IC Junction-to-Case Thermal Resistance
JCO
28
C/W
Thermocouple located at
center of package underside
1
Device considered a two-terminal device: Pins 1, 2, 3, 4, 5, 6, 7, and 8 shorted together, and Pins 9, 10, 11, 12, 13, 14, 15, and 16 shorted together.
2
Input capacitance is from any input data pin to ground.
REGULATORY INFORMATION
The ADM2490E is to be approved by the following organizations:
Table 4.
Organization Approval
Type
Notes
UL
To be recognized under 1577 component recognition program.
In accordance with UL1577, each ADM2490E
is proof-tested by applying an insulation
test voltage 3000 V rms for 1 second (current
leakage detection limit = 5 A).
CSA
To be approved under CSA Component Acceptance Notice #5A.
VDE
To be certified according to DIN EN 60747-5-2 (VDE 0884 Part 2): 2003-01
In accordance with VDE 0884, each
ADM2490E is proof-tested by applying an
insulation
test voltage 1050 V
PEAK
for 1 second
(partial discharge detection limit = 5 pC).
INSULATION AND SAFETY-RELATED SPECIFICATIONS
Table 5.
Parameter Symbol
Value
Unit
Conditions
Rated Dielectric Insulation Voltage
2500
V rms
1-minute duration.
Minimum External Air Gap (Clearance)
L(I01)
7.45 min
mm
Measured from input terminals to output
terminals, shortest distance through air.
Minimum External Tracking (Creepage)
L(I02)
8.1 min
mm
Measured from input terminals to output
terminals, shortest distance along body.
Minimum Internal Gap (Internal Clearance)
0.017 min
mm
Insulation distance through insulation.
Tracking Resistance (Comparative Tracking Index)
CTI
>175
V
DIN IEC 112/VDE 0303 Part 1.
Isolation Group
IIIa
Material Group (DIN VDE 0110, 1/89,).
Preliminary Technical Data
ADM2490E
Rev. PrI | Page 5 of 13
VDE 0884 INSULATION CHARACTERISTICS
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 asterisk (*) on packages denotes VDE 0884 approval for 560 V peak working voltage.
Table 6.
Description
Symbol Characteristic Unit
Installation classification per DIN VDE 0110 for rated mains voltage
150 V rms
I to IV
300 V rms
I to III
400 V rms
I to II
Climatic classification
40/85/21
Pollution degree (DIN VDE 0110, Table 1)
2
Maximum working insulation voltage
V
IORM
560
V
PEAK
Input to output test voltage, Method b1
V
PR
1050
V
PEAK
V
IORM
1.875 = V
PR
, 100% production tested, t
m
= 1 sec, partial discharge < 5 pC
Input to output test voltage, Method a
(After environmental tests, Subgroup 1)
V
IORM
1.6 = V
PR
, t
m
= 60 sec, partial discharge < 5 pC
896
V
PEAK
(After input and/or safety test, Subgroup 2/3)
V
IORM
1.2 = V
PR
, t
m
= 60 sec, partial discharge < 5 pC
V
PR
672
V
PEAK
Highest allowable overvoltage
(Transient overvoltage, t
TR
= 10 sec)
V
TR
4000
V
PEAK
Safety-limiting values (maximum value allowed in the event of a failure. See
thermal derating curve)
Case temperature
TS
150
C
Input current
I
S
,
INPUT
265 mA
Output current
I
S
,
OUTPUT
335 mA
Insulation resistance at Ts, V
IO
= 500 V
Rs
>10
9
ADM2490E
Preliminary Technical Data
Rev. PrI | Page 6 of 13
PIN CONFIGURATION AND FUNCTIONAL DESCRIPTIONS
1
ADM2490E
VDD1
GND1
RxD
NC
GND1
VDD2
GND2
A
B
NC
2
3
4
5
16
15
14
13
12
T OP VIEW
( Not t o Scale)
TxD
NC
GND1
6
7
8
Z
Y
GND2
11
10
9
Figure 2. ADM2490E Pin Out
Table 7.Preliminary Pin Function Description
Pin(s) Mnemonic Function
1 V
DD1
Power supply, logic side. Decoupling capacitor to GND
1
required, capacitor value should be between 0.01 F
and 0.1 F.
2,5,8 GND
1
Ground, logic side
3 RxD Receiver
output.
4,7,12
NC
No Connect, pins must be left floating
6 TxD Transmit
data
9,15 GND
2
Ground, bus side
16 V
DD2
Power supply, bus side. Decoupling capacitor to GND
2
required, capacitor value should be between 0.01 F
and 0.1 F.
9, 15
GND
2
Ground, bus side
11
Z
Driver Inverting Output
10
Y
Driver Non-inverting Output
13
B
Receiver Inverting Input
14
A
Receiver Non-inverting Input
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.
Preliminary Technical Data
ADM2490E
Rev. PrI | Page 7 of 13
TEST CIRCUITS
V
OD
R
R
V
OC
Figure 3. Driver Voltage Measurement
V
OD3
60
375
375
V
TST
Figure 4. Driver Voltage Measurement
R
LDIFF
A
B
C
L1
C
L2
Figure 5. Driver Propagation Delay
4-
A
B
C
L
V
OUT
Figure 6. Receiver Propagation Delay
SWITCHING CHARACTERISTICS
Figure 7. Driver Propagation Delay, Rise/Fall Timing
A, B
RO
0V
t
PLH
1.5V
0V
t
PHL
1.5V
V
OH
V
OL
Figure 8. Receiver Propagation Delay
Z
Y
ADM2490E
Preliminary Technical Data
Rev. PrI | Page 8 of 13
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 3. Unloaded Supply Current vs. Temperature
Figure 4. Driver Propagation Delay vs. Temperature
Figure 5. Receiver Propagation Delay vs. Temperature
Figure 6. Driver/Receiver Propagation Delay, Low to High
(R
LDiff
= 54 , C
L1
= C
L2
= 100 pF)
Figure 7. Driver/Receiver Propagation Delay, High to Low
(R
LDiff
= 54 , C
L1
= C
L2
= 100 pF)
Figure 8. Thermal Derating Curve, Dependence of Safety-Limiting Values
with Case Temperature per VDE 0884
Preliminary Technical Data
ADM2490E
Rev. PrI | Page 9 of 13
Figure 9. Output Current vs. Receiver Output High Voltage
Figure 10. Output Current vs. Receiver Output Low Voltage
Figure 11. Receiver Output High Voltage vs. Temperature
I
RxD
= -4 mA
Figure 12. Receiver Output Low Voltage vs. Temperature
I
RxD
= 4 mA
ADM2490E
Preliminary Technical Data
Rev. PrI | Page 10 of 13
CIRCUIT DESCRIPTION
ELECTRICAL ISOLATION
In the ADM2490, 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 9). Driver input signal, applied to the TxD pin, and
referenced to logic ground (GND
1
), are coupled across an
isolation barrier to appear at the transceiver section referenced
to isolated ground (GND
2
). Similarly, the receiver output,
referenced to isolated ground in the transceiver section, is
coupled across the isolation barrier to appear at the RxD pin
referenced to logic ground.
iCoupler Technology
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 then decoded into the binary value that
was originally transmitted.
ENCODE
DECODE
DECODE
ENCODE
TxD
RxD
V
DD1
V
DD2
GND
1
GND
2
Y
Z
DIGITAL ISOLATION
TRANSCEIVER
ISOLATION
BARRIER
D
R
A
B
Figure 9. ADM2490E Digital Isolation and Transceiver Sections
TRUTH TABLES
The truth tables in this section use these abbreviations:
Letter Description
H High
level
I Indeterminate
L Low
level
X Irrelevant
Z
High impedance (off)
NC
Disconnected
Table 8. Transmitting
Supply Status
Inputs Output
V
DD1
V
DD2
TxD
Y Z
On On H H
L
On On L L
H
Table 9. Receiving
Supply Status
Inputs Output
V
DD1
V
DD2
A-B
(V) RxD
On On
>0.2
H
On On
<-0.2
L
On
On
-0.2 < A - B < 0.2
I
On On Inputs
open
H
On Off
X
H
Off On
X
H
Off Off
X
L
Preliminary Technical Data
ADM2490E
Rev. PrI | Page 11 of 13
THERMAL SHUTDOWN
The ADM2490E contains thermal shutdown circuitry that
protects the part 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 150C is reached. As the device cools, the
drivers are re-enabled at a temperature of 140C.
RECEIVER FAIL-SAFE INPUTS
The receiver input includes a fail-safe feature that guarantees a
logic high on the RxD pin when the A and B inputs are floating
or open-circuited.
MAGNETIC FIELD IMMUNITY
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
analysis below defines the conditions under which this may
occur. The ADM2409E's 3 V operating condition is examined
because it represents the most susceptible mode of operation.
The limitation on the iCoupler's ac magnetic field immunity is
set by the condition in which the induced error voltage in the
receiving coil (the bottom coil in this case) is made sufficiently
large, either to falsely set or reset the decoder. The voltage
induced across the bottom coil is given by
-
=
2
n
r
dt
d
V
;
N
n
,
.
.
.
,
2
,
1
=
where, if the pulses at the transformer output are greater than
1.0 V in amplitude:
= magnetic flux density (gauss)
N = number of turns in receiving coil
r
n
= radius of nth turn in receiving coil (cm)
The decoder has a sensing threshold of about 0.5 V; therefore,
there is a 0.5 V margin in which induced voltages can be
tolerated.
Given the geometry of the receiving coil and an imposed
requirement that the induced voltage is, at most, 50% of the
0.5 V margin at the decoder, a maximum allowable magnetic
field is calculated, as shown in Figure 10.
04604-016
MAGNETIC FIELD FREQUENCY (Hz)
MAX
I
MUM ALLO
WABLE
MAG
N
E
T
IC
FLUX
DE
NS
ITY
(k
GAUS
S
)
1k
0.001
100
10
0.1
1
0.01
10k
100k
100M
1M
10M
Figure10. 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 the worst-case polarity, it reduces the received pulse
from >1.0 V to 0.75 V--still well above the 0.5 V sensing
threshold of the decoder.
Figure 11 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.
04604-017
MAGNETIC FIELD FREQUENCY (Hz)
MAX
I
MUM ALLOWABLE
CURRE
NT (k
A)
1k
0.01
1000
100
1
10
0.1
10k
100k
100M
1M
10M
DISTANCE = 1m
DISTANCE = 100mm
DISTANCE = 5mm
Figure11. Maximum Allowable Current for
Various Current-to-ADM2490E Spacings
At combinations of strong magnetic field and high frequency,
any loops formed by printed circuit board traces could induce
sufficiently large error voltages to trigger the thresholds of
succeeding circuitry. Care should be taken in the layout of such
traces to avoid this possibility.
ADM2490E
Preliminary Technical Data
Rev. PrI | Page 12 of 13
APPLICATIONS INFORMATION
ISOLATED POWER SUPPLY CIRCUIT
The ADM2490E requires isolated power capable of 5 V at
100 mA to be supplied between the V
DD2
and the GND
2
pins. A
transformer driver circuit with a center-tapped transformer
and LDO can be used to generate the isolated 5V supply as
shown in figure 12 below. The center-tapped transformer
provides electrical isolation of the 5V isolated power supply.
The primary winding of the transformer is excited with a pair
of square waveforms that are 180 out of phase with each other.
A pair of Schottky 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 ADM2490E's bus-side circuitry (VDD2).
V
CC
ADP667
IN
OUT
GND
SET
SHDN
V
DD2
GND
2
V
DD1
GND
1
V
CC
ISOLATION BARRIER
SD103C
SD103C
22
F
+5V
78253
ADM2490E
10
F
Transformer
Driver
Vcc
Figure 12. Isolated Power Supply Circuit
PC BOARD LAYOUT
The ADM2490E isolated RS-485 transceiver requires no
external interface circuitry for the logic interfaces. Power
supply bypassing is strongly recommended at the input and
output supply pins (Figure 13). Bypass capacitors are most
conveniently connected between Pins 1 and 2 for V
DD1
and
between Pins 15 and 16 for V
DD2
. The capacitor value should be
between 0.01 F and 0.1 F. The total lead length between both
ends of the capacitor and the input power supply pin should
not exceed 20 mm. Bypass-ing between Pins 1 and 8 and
between Pins 9 and 16 should also be considered unless the
ground pair on each package side is connected close to the
package.
V
DD1
GND
1
RxD
NC
GND
1
TxD
NC
GND
1
V
DD2
GND
2
A
B
NC
Z
Y
GND
2
NC = NO CONNECT
ADM2490E
Figure13.
Recommended Printed Circuit Board Layout
In applications involving high common-mode transients, care
should be taken 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 device's Absolute Maximum Ratings, thereby
leading to latch-up or permanent damage.
Product Concept Document
ADM2490E
Rev. PrI | Page 13 of 13
OUTLINE DIMENSIONS
16
9
8
1
PIN 1
0.413 (10.50)
0.299
(7.60)
0.419
(10.65)
SEATING
PLANE
0.05 (1.27)
BSC
0.019
(0.49)
0.012
(0.3)
0.014
(2.65)
0.030
(0.75)
0.013
(0.32)
0.042
(1.07)
Figure 14. 16-Lead Wide-Body Small Outline Package [SOIC]
(RW-16)
Dimensions shown in millimeters
ORDERING GUIDE
1
Z = Pb-free part.
Model Temperature
Range
Package Description
Package Option
ADM2490EWRWZ
1
40C to +105C
16-Lead Wide Body SOIC
RW-16
ADM2490EWRWZREEL7
1
40C to +105C
16-Lead Wide Body SOIC
RW-16
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registered trademarks are the property of their respective owners.
PR05889-0-1/06(PrI)
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