Analog Devices UG-197 User manual

Evaluation Board User Guide
UG-197
One Technology Way •P. O. Box 9106 •Norwood, MA 02062-9106, U.S.A. •Tel: [phone] •Fax: [phone] •www.analog.com
iCoupler ADuM347x Quad-Channel Isolators with Integrated Transformer Driver
Evaluation Board
See the last page for an important warning and disclaimers. Rev. 0 | Page 1 of 16
FEATURES
2 independent ADuM347x circuits including 2.5 kVrms
isolated dc-to-dc converters
Single supply
5 V in to 5 V out (regulated)
Reconfigurable to 5 V in to 3.3 V out or 3.3 V in
to 3.3 V out
Double supply
5 V in to 15 V out (regulated) and 7.5 V out (unregulated)
Reconfigurable to 5 V in to 12 V out (regulated) and 6 V
out (unregulated)
4 isolated 25 Mbps data channels per ADuM347x circuit
Footprints for Coilcraft and Halo transformer options
Multiple switching frequency options
GENERAL DESCRIPTION
The E VA L -ADuM3471EBZ demonstrates two separate
applications for the ADuM347x family of quad-channel digital
isolators with integrated transformer drivers. It has two
independent power supply circuits: a double supply and a single
supply. The switching frequency can be set from 200 kHz to
1000 kHz. The board supports a variety of I/O configurations
and multiple transformer options. It is equipped with two
ADuM3471 isolators.
SUPPORTED iCoupler MODELS
ADuM3470
ADuM3471
ADuM3472
ADuM3473
ADuM3474
EVALUATION BOARD
09417-001
Figure 1. ADuM3471 Evaluation Board

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TABLE OF CONTENTS
Features .............................................................................................. 1
General Description ......................................................................... 1
Supported iCoupler models ............................................................ 1
Evaluation Board .............................................................................. 1
Revision History ............................................................................... 2
Single Supply ..................................................................................... 3
Terminals ....................................................................................... 3
Transformer Selection.................................................................. 4
Switching Frequency Options..................................................... 4
Other Input and Isolated Output Supply Options ................... 4
Schematic........................................................................................6
Double Supply....................................................................................7
Terminals........................................................................................7
Transformer Selection ..................................................................8
Switching Frequency Options......................................................8
Other Secondary Isolated Supply Configurations ................. 10
Schematic..................................................................................... 10
Evaluation Board Layout ............................................................... 11
Ordering Information.................................................................... 12
Bill of Materials........................................................................... 12
REVISION HISTORY
10/10—Revision 0: Initial Version

Evaluation Board User Guide UG-197
Rev. 0 | Page 3 of 16
SINGLE SUPPLY
Two independent and isolated circuits comprise the ADuM3471
evaluation board. The lower half of the board, shown in Figure
2, is a single power supply configuration (see the appropriate
ADuM347x data sheet for applications information about the
ADuM347x in this configuration).
09417-002
Figure 2. Single Supply
The single supply comes configured as a 5 V secondary isolated
supply with a 5 V primary input supply, which can provide up
to 2.5 W of regulated, isolated power. It can be reconfigured for
a 3.3 V secondary isolated supply with a 5 V or 3.3 V primary
input supply (see the Other Input and Isolated Output Supply
Options section). Figure 9 shows the single supply schematic.
TERMINALS
The single supply has terminal blocks on Side 1 (the primary/
power supply input side) and Side 2 (the secondary/power supply
output side). A 4.3 mm isolation barrier separates Side 1 and
Side 2. Figure 3 shows these terminal locations. Although the
board is populated with the ADuM3471, it is designed to
accommodate the entire ADuM347x family. Therefore, the
silkscreen shows I/Ox to denote the four iCoupler® data
channels.
J1 and J3 are 0.1 inch (2.54 mm) 6x1 headers. J2 has pads for an
optional SMA connector (not populated) terminated into 50 Ω.
Table 1 summarizes the functions of the terminal connections.
They are described in detail in the Input Power Connections,
Output Power Connections, and Data I/O Connection sections.
09417-003
SIDE 1 TERMINALSIDE 2 TERMINAL
Figure 3. Single Supply Terminals
Input Power Connections
Connect +5 V to Pin 1 of J1, labeled +5V IN (or +3.3 V for a
3.3 V primary input supply with a 3.3 V secondary isolated
supply). Connect the supply negative to Pin 6, labeled GND
(GND1 in the schematic). These are the only off-board
connections required for the single supply to function.
+5 V IN supplies VDD1 and VDDA to U1, the single supply
ADuM3471. VDD1 is the ADuM3471 transformer driver supply,
and VDDA is its primary supply voltage (see the ADuM347x data
sheet for additional information about these pin functions).
VDD1/VDDA is bypassed by a 47 µF ceramic capacitor, labeled C1,
and a 0.1 µF local bypass capacitor located close to the ADuM3471
(C2). R15, R16, C28, and C29 are provided for an optional and
unpopulated snubber, which can be used to reduce radiated
emissions.
Power is transferred to Side 2 by a regulated push-pull converter
comprising the ADuM3471 (U1), an external transformer (T1
or T2), and other components (see the ADuM347x data sheet
for an explanation of this circuit functionality).
Output Power Connections
An output load can be connected to Pin 1 of J3, labeled +5V/3.3V
in the silkscreen and +5V/3.3V OUT in the schematic, which is
the isolated, regulated 5 V output supply. Connect the return of
the load to Pin 6 of J3, labeled GND ISO, which is the Side 2
ground reference. It is named GND2 in the schematic. Including
the current necessary for the ADuM3471 secondary side (I/O
and PWM control), this supply can provide up to 500 mA in the
default 5 V primary input supply, 5 V secondary isolated supply
configuration. The isolated data channels on Side 2 load the
secondary isolated supply and reduce the total available current.
See the ADuM347x data sheet electrical characteristics for speci-
fications on output supply current to determine how much
current the Side 2 I/O lines require at a given data rate. Figure 5
through Figure 8 in this user guide show how the power
supply’s efficiency varies with load current, switching frequency,
and temperature.
Data I/O Connection
The EVAL-ADuM3471 supports a variety of I/O configurations.
The user has access to all four of the ADuM3471 digital isolation
channels via the terminals. With an ADuM3471 populated,
I/O1 through I/O3 are inputs on Side 1 and outputs on Side 2.
I/O4 is an output on Side 1 and an input on Side 2. Table 1
identifies the ADuM3471 pins to which the I/Ox are connected.
Populating J2 allows the user to connect the ADuM3471 VIA
input directly to a 50 Ω signal source. R33 must be shorted with
a 0 Ω resistor to connect the SMA to VIA. R34, R35, and R36
allow the user to implement various I/O interconnection
schemes. For example, soldering 0 Ω 0805s to R34 and R35 ties
VIA, VIB, and VIC together.
Note that R36 must not be populated if an external signal
source is applied to I/O3. This can cause permanent damage to
the ADuM3471 because an output pin is being driven. R36 can
be used to connect VIC to VOD so that VOD drives VIC. C5
through C7 and C9 should not be populated when an

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ADuM3471 is equipped. C8, C10, C11, and C12 are 0603 pads
for optional and unpopulated loads for the data outputs.
Table 1: Single Supply Terminal Function Descriptions
Terminal Pin Label Description
J1 1 +5V IN Side 1 +5 V primary input
supply
2 I/O1 VIA Logic Input A
3 I/O2 VIB Logic Input B
4 I/O3 VIC Logic Input C
5 I/O4 VOD Logic Output D
6 GND Side 1 ground reference
J2 N/A N/A SMA connector to J1, I/O1 (VIA)
J3 1 +5V/3.3V Side 2 +5 V secondary isolated
supply
2 I/O1 VOA Logic Output A
3 I/O2 VOB Logic Output B
4 I/O3 VOC Logic Output C
5 I/O4 VID Logic Input D
6 GND ISO Side 2 ground reference
The PCB was designed for compatibility with the entire
ADuM347x family. If another ADuM347x replaces the
ADuM3471, other I/O interconnection schemes are possible.
See the ADuM347x data sheet for the pin descriptions of these
configurations. These changes are at the discretion of the user.
Care must be taken to avoid driving an output pin with an
external voltage because this can result in permanent damage to
the ADuM347x.
TRANSFORMER SELECTION
The EVAL-ADuM3471 supports multiple transformer options.
The single supply is equipped with a Halo TGSAD-260V6LF
(T1) or a Coilcraft JA4631-BL(T2) 1:2 turns ratio transformer.
The Coilcraft footprint is offset to the left of the Halo footprint.
Figure 5 and Figure 7 show the efficiency curves for the single
supply operating with either transformer.
SWITCHING FREQUENCY OPTIONS
The resistor connected from the ADuM3471 OC/oscillator
control pin to ground sets the single supply switching frequency.
Figure 4 shows the relationship between this resistance and the
converter switching frequency. The EVAL-ADuM347x can be
configured with 0 Ω 0805s to four different preset switching
frequencies. Short-circuiting R30 sets R1 (300 kΩ) and R2
(150 kΩ) in parallel, and short-circuiting R31 sets R1 and R3
(100 k Ω) in parallel.Table 2 lists the switching frequencies that
can be selected by short- or open-circuiting R30 and R31.
The user can select a different switching frequency by removing
R30 and R31 and then choosing R1 based on Figure 4. The
board is configured for the 500 kHz setting by default. Figure 5
and Figure 7 show how the switching frequency affects the
supply’s efficiency with either transformer equipped. Figure 6
shows how the efficiency curve varies over temperature with a
500 kHz switching frequency.
Table 2. Switching Frequency Selection
R30 R31 ROC Switching Frequency
Open Open 300 kΩ 200 kHz
0 Ω Open 100 kΩ 500 kHz
Open 0 Ω 75 kΩ 700 kHz
0 Ω 0 Ω 50 kΩ 1 MHz
1500
1400
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
0050 100 150 200 250 300 350 400 450 500
SWITCHING FREQUENCY (kHz)
ROC (kΩ)
09417-004
Figure 4. Switching Frequency vs. ROC Resistance
OTHER INPUT AND ISOLATED OUTPUT SUPPLY
OPTIONS
The single supply can be configured to have a 3.3 V secondary
isolated supply with a 3.3 V or 5 V primary input supply. Short-
circuiting R4 by soldering a 0 Ω 0805 to R32 sets the output
supply for 3.3 V. The voltage at the feedback node (the FB pin of
the ADuM3471) should be the desired output voltage divided to
approximately 1.25 V. Having R32 open-circuited sets the
secondary isolated supply to 5 V, and having it short-circuited
sets the supply to 3.3 V. See the ADuM347x data sheet for more
details on setting the secondary isolated output supply voltage.
Figure 8 shows how the single supply’s efficiency curve changes
when it is reconfigured for either of these supply options.

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0
10
20
30
40
50
60
70
80
EFFICIENCY(%)
LOAD CURRENT (mA)
1MHz
700kHz
500kHz
200kHz
050 100 150 200 250 300 350 400 500450
09417-005
Figure 5. 5 V In to 5 V Out Efficiency with the Coilcraft Transformer at Various
Switching Frequencies
0
10
20
30
40
50
60
70
80
050 100 150 200 250 300 350 400 500450
EFFICIENCY(%)
LOAD CURRENT (mA)
–40°C
+25°C
+105°C
09417-006
Figure 6. 5 V In to 5 V Out Efficiency with the Coilcraft Transformer at 500 kHz
over Temperature
0
10
20
30
40
50
60
70
80
050 100 150 200 250 300 350 400 500450
EFFICIENCY(%)
LOAD CURRENT (mA)
1MHz
700kHz
500kHz
200kHz
09417-007
Figure 7. 5 V In to 5 V Out Efficiency with the Halo Transformer at Various
Switching Frequencies
0
10
20
30
40
50
60
70
80
050 100 150 200 250 300 350 450
400 500
EFFICIENCY(%)
LOAD CURRENT (mA)
09417-008
5V IN TO 5V OUT
5V IN TO 3.3V OUT
3.3V IN TO 3.3V OUT
Figure 8. Single Supply Efficiency for Various Output Configurations with the
Coilcraft Transformer at 500 kHz

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SCHEMATIC
09417-009
Figure 9. Single Supply Schematic

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DOUBLE SUPPLY
The second power supply implemented with the ADuM3471 on
this evaluation board is a double supply. This circuit, which is
shown in Figure 10, is located on the top half of the board. The
ADuM347x data sheet also discusses the ADuM347x in this
configuration. Figure 17 shows the schematic.
09417-010
Figure 10. Double Supply
In its default configuration, the double supply provides a
regulated 15 V output and an unregulated 7.5 V output, which
are isolated from the 5 V primary input supply. The double
supply is capable of delivering up to 140 mA to external loads.
The isolated data channels on Side 2 load the secondary isolated
supply and reduce the total available current. See the ADuM347x
data sheet electrical characteristics for specifications on output
supply current to determine how much current the Side 2 I/O
lines require at a given data rate. It can be reconfigured as 12 V
(regulated) and 6 V (unregulated) secondary isolated supplies
or as positive and negative supplies. See the Other Secondary
Isolated Supply Configurations section for more details.
09417-011
SIDE 1 TERMINALSIDE 2 TERMINAL
Figure 11. Double Supply Terminals
TERMINALS
The double supply has terminal blocks on Side 1 (the primary/
power supply input side) and Side 2 (the secondary/power
supply output side). A 4.3 mm isolation barrier separates Side 1
and Side 2. Figure 11 shows these terminals. Although the board
is populated with the ADuM3471, it is designed to accommo-
date the entire ADuM347x family. Therefore, the silkscreen
shows I/Ox to denote the four iCoupler data channels. J4 is a 0.1
inch (2.54 mm) 6x1 header, and J6 is a 0.1 inch 7x1 header. J5
has pads for an optional SMA connector (not populated)
terminated into 50 Ω. Table 3 summarizes the functions of the
terminal connections. They are described in detail in the Input
Power Connections, Output Power Connections, and Data I/O
Connection sections.
Input Power Connections
Connect +5 V to Pin 1 of J4, labeled +5V IN. Connect the
supply negative to Pin 6, labeled GND (GND3 in the schematic).
These are the only off-board connections required for the
double supply to function.
+5V IN supplies VDD1 and VDDA to U2, the double supply
ADuM3471. VDD1 is the ADuM3471 transformer driver supply,
and VDDA is its primary supply voltage (see the ADuM347x data
sheet for additional information about these pin functions).
VDD1/VDDA is bypassed by a 47 µF ceramic capacitor, labeled
C13, and a 0.1 µF local bypass capacitor located close to the
ADuM3471 (C18). R17, R18, C30, and C31 are provided for an
optional and unpopulated snubber, which can be used to reduce
radiated emissions.
Output Power Connections
An output load can be connected to Pin 1 of J6, labeled VISO2
in the schematic and +15/12V in the silkscreen, which is the
isolated, regulated 15 V output supply. Connect the return of
the load to Pin 7 of J6. It is labeled GND ISO on the silkscreen
and GND4 in the schematic.
Side 2 is powered by the secondary isolated 15 V supply. The
ADuM3471 internal low-dropout regulator converts this
voltage to 5 V. The regulated 5 V supply powers the ADuM3471
secondary side. Therefore, the ADuM3471 VREG pin is 15 V, and
the VDD2 pin is 5 V. The 15 V supply connects to Pin 1 of J6. The
7.5 V supply connects to Pin 2 of J6, which is labeled +7.5V/6V
on the silkscreen and VISO1 on the schematic. The Side 2
ground reference is tied to Pin 7 of J6. Note that the single and
double supplies do not share grounds, though they have the
same names on the silkscreen. The two supplies are isolated
from each other with an over 15 mm gap. See the ADuM347x
data sheet for an explanation of the double supply theory of
operation. Figure 12 through Figure 15 shows efficiency curves
for the double supply with the +15/+12 V isolated output supply
connected to VREG.
Powering VREG from the Unregulated 7.5 V
VREG can be powered by the unregulated 7.5 V supply, which
results in higher efficiency. However, when the 15 V supply is
unloaded, the unregulated 7.5 V supply is approximately 3 V,
which is not high enough to power the ADuM3471 secondary
side. This causes the double supply to run open loop, leaving
the 15 V supply unregulated. Because the secondary side of the
ADuM3471 is not sufficiently powered, its data channels are
inoperable. Using 15 V for VREG ensures that the secondary side
of the ADuM3471 powers up under light load conditions. Move
the 0 Ω 0805 from R19 to R20 to power Side 2 from the 7.5 V
supply.

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Data I/O Connection
The EVAL-ADuM3471 supports a variety of I/O configurations.
The user has access to all four of the ADuM3471 isolated data
channels via the terminals. With an ADuM3471 populated,
I/O1 through I/O3 are inputs on Side 1 and outputs on Side 2.
I/O4 is an output on Side 1 and an input on Side 2. Table 3
identifies the ADuM3471 pins to which the I/Ox are connected.
Populating J5 allows the user to connect the ADuM3471 VIA
input directly to a 50 Ω signal source. R37 must be shorted with
a 0 Ω resistor to connect the SMA to VIA. R38, R39, and R40
allow the user to implement various I/O interconnection
schemes. For example, soldering 0 Ω 0805s to R40 and R39 ties
VIA, VIB, and VIC together.
Note that R38 must not be populated if an external signal
source is applied to I/O3. This can cause permanent damage to
the ADuM3471 because an output pin is being driven. R38 can
be used to connect VIC to VOD so that VOD drives VIC. C14
through C16 and C22 should not be populated. C17, C23, C24,
and C25 are 0603 pads provided for optional and unpopulated
loads for the data outputs. Though the I/Ox for the single and
double supplies share names on the silkscreen, they are not
connected.
The PCB is designed for compatibility with the entire
ADuM347x family. If the ADuM3471 is replaced by another
ADuM347x, other I/O interconnection schemes are possible
(see the ADuM347x data sheet for the pin descriptions of these
configurations). These changes are at the discretion of the user.
Care must be taken to avoid driving an output pin because this
can result in permanent damage to the ADuM347x.
Table 3. Double Supply Terminal Function Descriptions
Terminal Pin Label Description
J4 1 +5V IN Side 1 +5 V primary input
supply
2 I/O1 VIA Logic Input A
3 I/O2 VIB Logic Input B
4 I/O3 VIC Logic Input C
5 I/O4 VOD Logic Output D
6 GND Side 1 ground reference
J5 N/A N/A SMA connector to J4, I/O1 (VIA)
J6 1 +15V/12V Side 2 +15 V secondary
isolated supply (regulated)
2 +7.5V/6V Side 2 +7.5 V secondary
isolated supply (unregulated)
3 I/O1 VOA Logic Output A
4 I/O2 VOB Logic Output B
5 I/O3 VOC Logic Output C
6 I/O4 VID Logic Input D
7 GND ISO Side 2 ground reference
TRANSFORMER SELECTION
The EVAL-ADuM3471 supports multiple transformer options.
The double supply is equipped with a Halo TGSAD-290V6LF
(T3) or a Coilcraft JA4650-BL (T4) 1:3 turns ratio transformer.
The Coilcraft footprint is directly to the left of the Halo foot-
print (see the ADuM347x data sheet for a detailed discussion of
transformer selection with the ADuM347x). Figure 12 and
Figure 14 show the supply’s efficiency with either transformer at
different switching frequencies. Figure 13 shows how temper-
ature affects efficiency.
SWITCHING FREQUENCY OPTIONS
The resistor connected from the ADuM3471 OC/oscillator
control pin to ground sets the double supply switching frequency.
Figure 4 shows the relationship between this resistance and the
converter switching frequency. The EVAL-ADuM347x can be
configured with 0 Ω 0805s to four different preset switching
frequencies. Short-circuiting R26 sets R9 (300 kΩ) and R10
(150 kΩ) in parallel, and short-circuiting R27 sets R9 and R11
(100 kΩ) in parallel. Table 4 lists the switching frequencies that
can be selected by short- or open-circuiting R26 and R27. The
user can select a different switching frequency by removing R26
and R27 and then choosing R9 based on Figure 4. The board is
configured for the 500 kHz setting by default. Figure 12 and
Figure 14 show how the switching frequency affects the
efficiency with either transformer.
Table 4. Switching Frequency Selection
R26 R27 ROC Switching Frequency
Open Open 300 kΩ 200 kHz
0 Ω Open 100 kΩ 500 kHz
Open 0 Ω 75 kΩ 700 kHz
0 Ω 0 Ω 50 kΩ 1 MHz

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0
10
20
30
40
50
60
70
80
EFFICIENCY(%)
LOAD CURRENT (mA)
010 20 30 40 50 70 90 110 140130
60 80 100 120
09417-012
1MHz
700kHz
500kHz
200kHz
Figure 12. 5 V In to 15 V Out Efficiency with the Coilcraft Transformer at
Various Switching Frequencies
010 20 30 40 50 70 90 110 140130
60 80 100 120
0
10
20
30
40
50
60
70
80
EFFICIENCY(%)
LOAD CURRENT (mA)
–40°C
+25°C
+105°C
09417-013
Figure 13. 5 V In to 15 V Out Efficiency with the Coilcraft Transformer at
500 kHz and Various Temperatures
010 20 30 40 50 70 90 110 140130
60 80 100 120
0
10
20
30
40
50
60
70
80
EFFICIENCY(%)
LOAD CURRENT (mA)
1MHz
700kHz
500kHz
200kHz
09417-014
Figure 14. 5 V In to 15 V Out Efficiency with the Halo Transformer at Various
Switching Frequencies
010 20 30 40 50 70 90 110 140130
60 80 100 120
0
10
20
30
40
50
60
70
80
EFFICIENCY(%)
LOAD CURRENT (mA)
5V IN TO 15V OUT
5V IN TO 12V OUT
09417-015
Figure 15. Double Supply Efficiency with the Coilcraft Transformer for
Different Output Options at 500 kHz

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OTHER SECONDARY ISOLATED SUPPLY
CONFIGURATIONS
The double supply can be configured for 12 V regulated and 6 V
unregulated secondary isolated supplies by short-circuiting R12
with a 0 Ω resistor for R25. The regulated supply voltage is set
by the fraction of it that is fed back to the ADuM3471 via the
voltage divider comprising R12, R13, R14, and R25. The voltage
at the feedback pin is 1.25 V. With R25 open-circuited, the
ADuM3471 feedback voltage is approximately 1.25 V if VISO2
is 15 V. When R25 is short-circuited, the feedback voltage is
approximately 1.25 V if VISO2 is 12 V (see the ADuM347x data
sheet for more details on setting the secondary isolated output
supply voltage). Figure 15 shows the efficiency curves for both
output settings at 500 kHz with the Coilcraft transformer.
Positive and Negative Outputs
The double supply can be set up as a positive and negative ±15 V
supply by changing the transformer to a turns ratio CT1:CT5
transformer (see the ADuM347x data sheet for more information
on these transformers). Other changes begin with removing the
0 Ω resistors from R24 and R22 to R23 and R21. Short-circuiting
R23 instead of R24 makes the +7.5 V/6 V pin of J6 become the
−15 V supply. Short-circuiting R21 instead of R22 connects the
transformer center tap to the ground plane instead of the node
where L3, C20, and C27 are connected. Figure 16 shows which
resistors should be short-circuited and open-circuited for the
double supply or positive and negative supply configurations.
Note that the negative supply is unregulated. The positive and
negative supply can be set for ±12 V instead of ±15 V by short-
circuiting R25.
Whereas the +15 V output can be regulated, the same problems
with regulation can happen as described in the Powering VREG
from the Unregulated 7.5 V section. In addition, the −15 V
supply can vary over a wide range because it is unregulated and
influenced by the changes that happen on the +15 V output.
09417-016
DOUBLE SUPPLY POSITIVEAND NEGATIVE SUPPLY
Figure 16. Double Supply Configuration with 0 Ω Resistors (Red)
SCHEMATIC
09417-017
Figure 17. Double Supply Schematic