Isolated Switching Regulator With Integrated Feedback ADuM3070 Data Sheet

Isolated Switching Regulator With Integrated Feedback ADuM3070 Data Sheet
Isolated Switching Regulator
With Integrated Feedback
ADuM3070
Data Sheet
FEATURES
FUNCTIONAL BLOCK DIAGRAM
VISO
VDD1
RECT
X1
X2
VREG
ADuM3070
REG
VDDA
5V
PRIMARY
CONVERTER/
DRIVER
SECONDARY
CONTROLLER
INTERNAL
FEEDBACK
GND1
VDD2
FB
OC
GND2
NOTES
1. VDD1 IS THE POWER SUPPLY FOR THE PUSH-PULL TRANSFORMER.
2. VDDA IS THE POWER SUPPLY OF SIDE 1 OF THE ADuM3070.
10437-001
Isolated PWM feedback with built in compensation
Primary side transformer driver for up to 2.5 W output power
with 5 V input voltage
Regulated adjustable output: 3.3 V to 24 V
Up to 80% efficiency
200 kHz to 1 MHz adjustable oscillator
Soft start function at power-up
Pulse-by-pulse overcurrent protection
Thermal shutdown
2500 V rms isolation
High common-mode transient immunity: >25 kV/µs
16-lead QSOP package
High temperature operation: 105°C
Figure 1.
APPLICATIONS
Power supply startup bias and gate drives
Isolated sensor interfaces
Process controls
GENERAL DESCRIPTION
The ADuM30701 isolator is a regulated dc-to-dc isolated power
supply controller with an internal MOSFET driver. The dc-todc controller has an internal isolated PWM feedback from the
secondary side based on the iCoupler® chip scale transformer
technology and complete loop compensation. This eliminates
the need to use an optocoupler for feedback and compensates
the loop for stability.
1
The ADuM3070 isolator provides a more stable output voltage and
higher efficiency compared to unregulated isolated dc-to-dc power
supplies. The fully integrated feedback and loop compensation
in a small QSOP package provides a smaller form factor than any
discrete solution. The regulated feedback provides a relatively flat
efficiency curve over the full output power range. The ADuM3070
enables a dc-to-dc converter with a 3.3 V to 24 V isolated output
voltage range from either a 5.0 V or a 3.3 V input voltage, with
an output power of up to 2.5 W.
Protected by U.S. Patents 5,952,849; 6,873,065; and 7075 329 B2. Other patents are pending.
Rev. A
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ADuM3070
Data Sheet
TABLE OF CONTENTS
Features .............................................................................................. 1
Pin Configuration and Function Descriptions..............................8
Applications ....................................................................................... 1
Typical Performance Characteristics ..............................................9
Functional Block Diagram .............................................................. 1
Applications Information .............................................................. 14
General Description ......................................................................... 1
Application Schematics ............................................................. 14
Revision History ............................................................................... 2
Transformer Design ................................................................... 15
Specifications..................................................................................... 3
Transformer Turns Ratio ........................................................... 15
Electrical Characteristics—5 V Primary Input Supply/5 V
Secondary Isolated Supply .......................................................... 3
Transformer ET Constant ......................................................... 15
Electrical Characteristics—3.3 V Primary Input Supply/3.3 V
Secondary Isolated Supply .......................................................... 3
Transformer Isolation Voltage .................................................. 16
Electrical Characteristics—5 V Primary Input Supply/3.3 V
Secondary Isolated Supply .......................................................... 4
Transient Response .................................................................... 16
Transformer Primary Inductance and Resistance ................. 15
Switching Frequency .................................................................. 16
Electrical Characteristics—5 V Primary Input Supply/15 V
Secondary Isolated Supply .......................................................... 4
Component Selection ................................................................ 16
Package Characteristics ............................................................... 5
Thermal Analysis ....................................................................... 17
Regulatory Approvals (Pending) ................................................ 5
Power Consumption .................................................................. 17
Insulation and Safety Related Specifications ............................ 5
Power Considerations ................................................................ 18
DIN V VDE V 0884-10 (VDE V 0884-10) Insulation
Characteristics .............................................................................. 6
Insulation Lifetime ..................................................................... 18
Outline Dimensions ....................................................................... 19
Recommended Operating Conditions ...................................... 6
Ordering Guide .......................................................................... 19
Printed Circuit Board (PCB) Layout ....................................... 17
Absolute Maximum Ratings............................................................ 7
ESD Caution .................................................................................. 7
REVISION HISTORY
5/14—Rev. 0 to Rev. A
Change to Line Regulation Parameter, Table 4 ............................. 4
5/12—Revision 0: Initial Version
Rev. A | Page 2 of 20
Data Sheet
ADuM3070
SPECIFICATIONS
ELECTRICAL CHARACTERISTICS—5 V PRIMARY INPUT SUPPLY/5 V SECONDARY ISOLATED SUPPLY
4.5 V ≤ VDD1 = VDDA ≤ 5.5 V, VDD2 = VREG = VISO = 5.0 V, fSW = 500 kHz, all voltages are relative to their respective grounds, see the
application schematic in Figure 31. All minimum/maximum specifications apply over the entire recommended operating range, unless
otherwise noted. All typical specifications are at TA = 25°C, VDD1 = VDDA = 5.0 V, VDD2 = VREG = VISO = 5.0 V.
Table 1. DC-to-DC Converter Static Specifications
Parameter
DC-TO-DC CONVERTER SUPPLY
Isolated Output Voltage
Feedback Voltage Setpoint
Line Regulation
Load Regulation
Output Ripple
Output Noise
Switching Frequency
Symbol
Min
Typ
Max
Unit
Test Conditions/Comments
VISO
VFB
VISO (LINE)
VISO (LOAD)
VISO (RIP)
VISO (NOISE)
fSW
4.5
1.15
5.0
1.25
1
1
50
100
1000
200
318
4
0.5
500
70
5.5
1.37
10
2
V
V
mV/V
%
mV p-p
mV p-p
kHz
kHz
kHz
mA
Ω
mA
%
IISO = 0 mA, VISO = VFB × (R1 + R2)/R2
IISO = 0 mA
IISO = 50 mA, VDD1 1 = VDDA 2 = 4.5 V to 5.5 V
IISO = 50 mA to 200 mA
20 MHz bandwidth, COUT = 0.1 µF||47 µF, IISO = 100 mA
20 MHz bandwidth, COUT = 0.1 µF||47 µF, IISO = 100 mA
ROC = 50 kΩ
ROC = 270 kΩ
VOC = VDD2 (open-loop)
192
IDDA Quiescent
Switch On Resistance
Maximum Output Supply Current
Efficiency at Maximum Output Current
1
2
IDDA (Q)
RON
IISO (MAX)
400
515
5
f ≤ 1 MHz, VISO = 5.0 V
IISO = IISO (MAX), f ≤ 1 MHz
VDD1 is the power supply for the push-pull transformer.
VDDA is the power supply of Side 1 of the ADuM3070.
ELECTRICAL CHARACTERISTICS—3.3 V PRIMARY INPUT SUPPLY/3.3 V SECONDARY ISOLATED SUPPLY
3.0 V ≤ VDD1 = VDDA ≤ 3.6 V, VDD2 = VREG = VISO = 3.3 V, fSW = 500 kHz, all voltages are relative to their respective grounds, see the application
schematic in Figure 31. All minimum/maximum specifications apply over the entire recommended operating range, unless otherwise
noted. All typical specifications are at TA = 25°C, VDD1 = VDDA = 3.3 V, VDD2 = VREG = VISO = 3.3 V.
Table 2. DC-to-DC Converter Static Specifications
Parameter
DC-TO-DC CONVERTER SUPPLY
Isolated Output Voltage
Feedback Voltage Setpoint
Line Regulation
Load Regulation
Output Ripple
Output Noise
Switching Frequency
Symbol
Min
Typ
Max
Unit
Test Conditions/Comments
VISO
VFB
VISO (LINE)
VISO (LOAD)
VISO (RIP)
VISO (NOISE)
fSW
3.0
1.15
3.3
1.25
1
1
50
100
1000
200
318
2
0.6
350
70
3.63
1.37
10
2
V
V
mV/V
%
mV p-p
mV p-p
kHz
kHz
kHz
mA
Ω
mA
%
IISO = 0 mA, VISO = VFB × (R1 + R2)/R2
IISO = 0 mA
IISO = 50 mA, VDD1 1 = VDDA 2 = 3.0 V to 3.6 V
IISO = 50 mA to 200 mA
20 MHz bandwidth, COUT = 0.1 µF||47 µF, IISO = 100 mA
20 MHz bandwidth, COUT = 0.1 µF||47 µF, IISO = 100 mA
ROC = 50 kΩ
ROC = 270 kΩ
VOC = VDD2 (open-loop)
192
IDDA Quiescent
Switch On Resistance
Maximum Output Supply Current
Efficiency at Maximum Output Current
1
2
IDDA (Q)
RON
IISO (MAX)
250
515
3.5
VDD1 is the power supply for the push-pull transformer.
VDDA is the power supply of Side 1 of the ADuM3070.
Rev. A | Page 3 of 20
f ≤ 1 MHz, VISO = 3.3 V
IISO = IISO (MAX), f ≤ 1 MHz
ADuM3070
Data Sheet
ELECTRICAL CHARACTERISTICS—5 V PRIMARY INPUT SUPPLY/3.3 V SECONDARY ISOLATED SUPPLY
4.5 V ≤ VDD1 = VDDA ≤ 5.5 V, VDD2 = VREG = VISO = 3.3 V, fSW = 500 kHz, all voltages are relative to their respective grounds, see the application
schematic in Figure 31. All minimum/maximum specifications apply over the entire recommended operating range, unless otherwise noted. All
typical specifications are at TA = 25°C, VDD1 = VDDA = 5.0 V, VDD2 = VREG = VISO = 3.3 V.
Table 3. DC-to-DC Converter Static Specifications
Parameter
DC-TO-DC CONVERTER SUPPLY
Isolated Output Voltage
Feedback Voltage Setpoint
Line Regulation
Load Regulation
Output Ripple
Output Noise
Switching Frequency
Symbol
Min
Typ
Max
Unit
Test Conditions/Comments
VISO
VFB
VISO (LINE)
VISO (LOAD)
VISO (RIP)
VISO (NOISE)
fSW
3.0
1.15
3.3
1.25
1
1
50
100
1000
200
318
3.5
0.5
500
70
3.63
1.37
10
2
V
V
mV/V
%
mV p-p
mV p-p
kHz
kHz
kHz
mA
Ω
mA
%
IISO = 0 mA, VISO = VFB × (R1 + R2)/R2
IISO = 0 mA
IISO = 50 mA, VDD1 1 = VDDA 2 = 4.5 V to 5.5V
IISO = 50 mA to 200 mA
20 MHz bandwidth, COUT = 0.1 µF||47 µF, IISO = 100 mA
20 MHz bandwidth, COUT = 0.1 µF||47 µF, IISO = 100 mA
ROC = 50 kΩ
ROC = 270 kΩ
VOC = VDD2 (open-loop)
209
IDDA Quiescent
Switch On Resistance
Maximum Output Supply Current
Efficiency at Maximum Output Current
1
2
IDDA (Q)
RON
IISO (MAX)
400
515
5
f ≤ 1 MHz, VISO = 3.3 V
IISO = IISO (MAX), f ≤ 1 MHz
VDD1 is the power supply for the push-pull transformer.
VDDA is the power supply of Side 1 of the ADuM3070.
ELECTRICAL CHARACTERISTICS—5 V PRIMARY INPUT SUPPLY/15 V SECONDARY ISOLATED SUPPLY
4.5 V ≤ VDD1 = VDDA ≤ 5.5 V, VREG = VISO = 15 V, VDD2 = 5.0 V, fSW = 500 kHz, all voltages are relative to their respective grounds, see the
application schematic in Figure 32. All minimum/maximum specifications apply over the entire recommended operating range, unless
otherwise noted. All typical specifications are at TA = 25°C, VDD1 = VDDA = 5.0 V, VREG = VISO = 15 V, VDD2 = 5.0 V.
Table 4. DC-to-DC Converter Static Specifications
Parameter
DC-TO-DC CONVERTER SUPPLY
Isolated Output Voltage
Feedback Voltage Setpoint
VDD2 Linear Regulator Voltage
Dropout Voltage
Line Regulation
Load Regulation
Output Ripple
Output Noise
Switching Frequency
Symbol
Min
Typ
Max
Unit
Test Conditions/Comments
VISO
VFB
VDD2
VDD2DO
VISO (LINE)
VISO (LOAD)
VISO (RIP)
VISO (NOISE)
fSW
13.8
1.15
4.5
15.0
1.25
5.0
0.5
1
1
200
500
1000
200
318
3.5
0.5
140
70
16.5
1.37
5.48
1.5
20
3
V
V
V
V
mV/V
%
mV p-p
mV p-p
kHz
kHz
kHz
mA
Ω
mA
%
IISO = 0 mA, VISO = VFB × (R1 + R2)/R2
IISO = 0 mA
VREG = 7 V to 15 V, IDD2 = 0 mA to 50 mA
IDD2 = 50 mA
IISO = 50 mA, VDD1 1 = VDDA 2 = 4.5 V to 5.5 V
IISO = 20 mA to 100 mA
20 MHz bandwidth, COUT = 0.1 µF||47 µF, IISO = 100 mA
20 MHz bandwidth, COUT = 0.1 µF||47 µF, IISO = 100 mA
ROC = 50 kΩ
ROC = 270 kΩ
VOC = VDD2 (open-loop)
192
IDDA Quiescent
Switch On Resistance
Maximum Output Supply Current
Efficiency at Maximum Output Current
1
2
IDDA (Q)
RON
IISO (MAX)
100
515
5
VDD1 is the power supply for the push-pull transformer.
VDDA is the power supply of Side 1 of the ADuM3070.
Rev. A | Page 4 of 20
f ≤ 1 MHz, VISO = 15.0 V
IISO = IISO (MAX), f ≤ 1 MHz
Data Sheet
ADuM3070
PACKAGE CHARACTERISTICS
Table 5.
Parameter
RESISTANCE
Input to Output 1
CAPACITANCE
Input to Output1
THERMAL
IC Junction-to-Ambient Thermal Resistance 2
Thermal Shutdown
Threshold
Hysteresis
1
2
Symbol
RI-O
Min
Typ
1012
Max
Unit
Ω
Test Conditions/Comments
f = 1 MHz
CI-O
2.2
pF
θJA
76
°C/W
TSSD
TSSD-HYS
150
20
°C
°C
TJ rising
The device is considered a 2-terminal device: Pin 1 to Pin 8 is shorted together, and Pin 9 to Pin 16 is shorted together.
The thermocouple is located at the center of the package underside.
REGULATORY APPROVALS (PENDING)
Table 6.
UL
Recognized under the UL 1577
Component Recognition Program 1
Single Protection, 2500 V rms
Isolation Voltage
File E214100
1
2
CSA
Approved under CSA Component Acceptance Notice #5A
Basic insulation per CSA 60950-1-03 and IEC 60950-1,
400 V rms (848 V peak) maximum working voltage
File 205078
VDE
Certified according to DIN V VDE V
0884-10 (VDE V 0884-10):2006-12 2
Reinforced insulation, 560 V peak
File 2471900-4880-0001
In accordance with UL 1577, each ADuM3070 is proof tested by applying an insulation test voltage of ≥3000 V rms for 1 sec (current leakage detection limit = 10 µA).
In accordance with DIN V VDE V 0884-10, each ADuM3070 is proof tested by applying an insulation test voltage of ≥1050 V peak for 1 sec (partial discharge detection
limit = 5 pC). The asterisk (*) marking branded on the component designates DIN V VDE V 0884-10 approval.
INSULATION AND SAFETY RELATED SPECIFICATIONS
Table 7.
Parameter
Rated Dielectric Insulation Voltage
Minimum External Air Gap (Clearance)
Symbol
L(I01)
Value
2500
>3.8
Unit
V rms
mm
Minimum External Tracking (Creepage)
L(I02)
>3.1
mm
Minimum Internal Gap (Internal Clearance)
Tracking Resistance (Comparative Tracking Index) CTI
Isolation Group
0.017 min mm
>400
V
II
Rev. A | Page 5 of 20
Test Conditions/Comments
1-minute duration
Measured from input terminals to output terminals
along the printed circuit board (PCB) seating plane
Measured from input terminals to output terminals,
shortest distance path along body
Distance through insulation
DIN IEC 112/VDE 0303 Part 1
Material Group (DIN VDE 0110, 1/89, Table 1)
ADuM3070
Data Sheet
DIN V VDE V 0884-10 (VDE V 0884-10) INSULATION CHARACTERISTICS
These isolators are suitable for reinforced electrical isolation only within the safety limit data. Protective circuits ensure maintenance of
the safety data. The asterisk (*) marking on packages denotes DIN V VDE V 0884-10 approval.
Table 8.
Parameter
Installation Classification per DIN VDE 0110
For Rated Mains Voltage ≤ 150 V rms
For Rated Mains Voltage ≤ 300 V rms
For Rated Mains Voltage ≤ 400 V rms
Climatic Classification
Pollution Degree per DIN VDE 0110, Table 1
Maximum Working Insulation Voltage
Input-to-Output Test Voltage, Method b1
Test Conditions/Comments
VIORM × 1.875 = Vpd (m), 100% production test,
tini = tm = 1 sec, partial discharge < 5 pC
Input-to-Output Test Voltage, Method a
After Environmental Tests Subgroup 1
VIORM × 1.5 = Vpd (m), tini = 60 sec, tm = 10 sec,
partial discharge < 5 pC
VIORM × 1.2 = Vpd (m), tini = 60 sec, tm = 10 sec,
partial discharge < 5 pC
After Input and/or Safety Test Subgroup 2
and Subgroup 3
Highest Allowable Overvoltage
Withstand Isolation Voltage
Surge Isolation Voltage
Safety Limiting Values
1 minute withstand rating
VPEAK = 10 kV, 1.2 µs rise time, 50 µs, 50% fall time
Maximum value allowed in the event of a failure
(see Figure 2)
Case Temperature
Side 1, Side 2 PVDDA, PVREG Power Dissipation
Insulation Resistance at TS
VIO = 500 V
Symbol
Characteristic
Unit
VIORM
Vpd (m)
I to IV
I to III
I to II
40/105/21
2
560
1050
VPEAK
VPEAK
Vpd (m)
840
VPEAK
Vpd (m)
672
VPEAK
VIOTM
VISO
VIOSM
3500
2500
6000
VPEAK
VRMS
VPEAK
TS
PVDDA, PVREG
RS
150
1.65
>109
°C
W
Ω
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0
50
100
150
AMBIENT TEMPERATURE (°C)
200
10437-002
SAFE OPERATING PVDDA , PVREG POWER (mA)
1.8
Figure 2. Thermal Derating Curve, Dependence of Safety Limiting Values on Ambient Temperature, per DIN V VDE V 0884-10
RECOMMENDED OPERATING CONDITIONS
Table 9.
Parameter
TEMPERATURE
Operating Temperature
LOAD
Minimum Load
Symbol
Min
Max
Unit
TA
−40
+105
°C
IISO (MIN)
10
Rev. A | Page 6 of 20
mA
Data Sheet
ADuM3070
ABSOLUTE MAXIMUM RATINGS
TA = 25°C, unless otherwise noted.
Table 11. Maximum Continuous Working Voltage Supporting
50-Year Minimum Lifetime1
Table 10.
Parameter
Storage Temperature Range (TST)
Ambient Operating Temperature
Range (TA)
Supply Voltages
VDDA, VDD21, 2
VREG, X1, X21
Common-Mode Transients3
Rating
−55°C to +150°C
−40°C to +105°C
Parameter
AC Voltage
Bipolar Waveform
−0.5 V to +7.0 V
−0.5 V to +20.0 V
−100 kV/µs to +100 kV/µs
All voltages are relative to their respective ground.
VDD1 is the power supply for the push-pull transformer, and VDDA is the power
supply of Side 1 of the ADuM3070.
3
Refers to common-mode transients across the insulation barrier. Commonmode transients exceeding the absolute maximum ratings may cause latch-up
or permanent damage.
1
2
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.
Unipolar Waveform
Basic Insulation
DC Voltage
Basic Insulation
1
Applicable
Certification
Max
Unit
565
V peak
50-year minimum
lifetime, all
certifications
848
V peak
Working voltage
per IEC 60950-1
848
V peak
Working voltage
per IEC 60950-1
Refers to the continuous voltage magnitude imposed across the isolation
barrier. See the Insulation Lifetime section for more information.
ESD CAUTION
Rev. A | Page 7 of 20
ADuM3070
Data Sheet
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
X1
1
16 VREG
*GND1
2
15 GND2*
NC
3
ADuM3070
14 VDD2
X2
4
TOP VIEW
(Not to Scale)
13 FB
TP 5
12 NC
TP 6
11 NC
VDDA
7
*GND1
8
10 OC
9
GND2*
NOTES
1. NC = NO CONNECT. DO NOT CONNECT TO THIS PIN.
2. TP = TEST POINT. DO NOT CONNECT TO THIS PIN.
10437-003
*PIN 2 AND PIN 8 ARE INTERNALLY CONNECTED,
AND CONNECTING BOTH TO GND1 IS
RECOMMENDED. PIN 9 AND PIN 15 ARE
INTERNALLY CONNECTED, AND CONNECTING
BOTH TO GND2 IS RECOMMENDED.
Figure 3. Pin Configuration
See Application Note AN-1109 for specific layout guidelines.
Table 12. Pin Function Descriptions
Pin No.
1
2, 8
3, 11, 12
5, 6
4
7
9, 15
10
Mnemonic
X1
GND1
NC
TP
X2
VDDA
GND2
OC
13
FB
14
VDD2
16
VREG
Description
Transformer Driver Output 1.
Ground Reference for Primary Side.
No Connect. Do not connect to this pin.
Test Point. Do not connect to this pin.
Transformer Driver Output 2.
Primary Supply Voltage 3.0 V to 5.5 V. Connect to VDD1. Connect a 0.1 µF bypass capacitor from VDDA to GND1.
Ground Reference for Secondary Side.
Oscillator Control Pin. When OC = logic high = VDD2, the secondary controller runs open-loop. To regulate the
output voltage, connect a resistor between the OC pin and GND2, and the secondary controller runs at a
frequency of 200 kHz to 1 MHz, as programmed by the resistor value.
Feedback Input from the Secondary Output Voltage VISO. Use a resistor divider from VISO to the FB pin to make
the VFB voltage equal to the 1.25 V internal reference level using the VISO = VFB × (R1 + R2)/R2 formula. The resistor
divider is required even in open-loop mode to provide soft start.
Internal Supply Voltage Pin for the Secondary Side Controller. When a sufficient external voltage is supplied to
VREG, the internal regulator regulates the VDD2 pin to 5.0 V. Otherwise, VDD2 should be in the 3.0 V to 5.5 V range.
Connect a 0.1 µF bypass capacitor from VDD2 to GND2.
Input of the Internal Regulator to Power the Secondary Side Controller. VREG should be in the 5.5 V to 15 V range
to regulate the VDD2 output to 5.0 V.
Rev. A | Page 8 of 20
Data Sheet
ADuM3070
TYPICAL PERFORMANCE CHARACTERISTICS
1500
1400
90
80
1300
1200
70
1100
EFFICIENCY (%)
fSW (kHz)
1000
900
800
700
600
500
60
50
40
30
400
20
200
TA = –40°C
TA = +25°C
TA = +105°C
10
100
50
100
150
200
250
300
350
400
450
500
ROC (Ω)
0
80
80
70
70
60
60
EFFICIENCY (%)
90
50
40
30
fSW = 1MHz
fSW = 700kHz
fSW = 500kHz
fSW = 200kHz
0
0
50
100
150
200
250
300
350
400
450
500
LOAD CURRENT (mA)
200
250
300
350
400
450
500
50
40
30
5V IN TO 5V OUT
5V IN TO 3.3V OUT
3.3V IN TO 3.3V OUT
10
Figure 5. Typical Efficiency at 5 V In to 5 V Out at Various Switching
Frequencies with 1:2 Coilcraft Transformer (JA4631-BL)
0
0
50
100
150
200
250
300
350
400
450
500
LOAD CURRENT (mA)
Figure 8. Single-Supply Efficiency with 1:2 Coilcraft Transformer (JA4631-BL)
at 500 kHz fSW
90
80
80
70
70
60
50
40
30
10
0
0
50
100
150
200
250
300
350
400
450
500
LOAD CURRENT (mA)
40
30
20
fSW = 1MHz
fSW = 700kHz
fSW = 500kHz
fSW = 200kHz
20
50
fSW = 1MHz
fSW = 700kHz
fSW = 500kHz
fSW = 200kHz
10
0
0
50
100
150
200
LOAD CURRENT (mA)
250
300
10437-033
EFFICIENCY (%)
60
10437-006
EFFICIENCY (%)
150
20
10437-005
10
100
LOAD CURRENT (mA)
90
20
50
Figure 7. 5 V In to 5 V Out Efficiency over Temperature with 1:2 Coilcraft
Transformer (JA4631-BL) at 500 kHz fSW
Figure 4. Switching Frequency (fSW) vs. ROC Resistance
EFFICIENCY (%)
0
10437-008
0
10437-004
0
10437-007
300
Figure 9. Typical Efficiency at 3.3 V In to 5 V Out at Various Switching
Frequencies with 1:3 Halo Transformer (TGSAD-290V6LF)
Figure 6. Typical Efficiency at 5 V In to 5 V Out at Various Switching
Frequencies with 1:2 Halo Transformer (TGSAD-260V6LF)
Rev. A | Page 9 of 20
ADuM3070
Data Sheet
80
90
70
80
70
EFFICIENCY (%)
50
40
30
20
50
40
30
20
50
100
150
200
250
300
LOAD CURRENT (mA)
0
10437-034
0
0
TA = –40°C
TA = +25°C
TA = +105°C
10
Figure 10. Typical Efficiency at 3.3 V In to 5 V Out over Temperature with
1:3 Halo Transformer (TGSAD-290V6LF) at 500 kHz fSW
0
10
20
30
40
50
60
70
80
90 100 110 120 130 140
LOAD CURRENT (mA)
10437-011
TA = –40°C
TA = +25°C
TA = +105°C
10
Figure 13. 5 V In to 15 V Out Efficiency over Temperature with 1:3 Coilcraft
Transformer (JA4650-BL) at 500 kHz fSW
90
80
80
70
70
60
EFFICIENCY (%)
60
50
40
30
10
0
0
10
20
30
40
50
60
70
80
90 100 110 120 130 140
LOAD CURRENT (mA)
50
40
30
20
fSW = 1MHz
fSW = 700kHz
fSW = 500kHz
fSW = 200kHz
20
10
Figure 11. 5 V In to 15 V Out Efficiency at Various Switching Frequencies with
1:3 Coilcraft Transformer (JA4650-BL)
5V IN TO 12V OUT
5V IN TO 15V OUT
0
10437-009
EFFICIENCY (%)
60
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
LOAD CURRENT (mA)
10437-012
EFFICIENCY (%)
60
Figure 14. Double-Supply Efficiency with 1:5 Coilcraft Transformer (KA4976-AL)
at 500 kHz fSW
6
90
80
5
60
VISO (V)
4
50
40
30
3
2
20
10
0
0
10
20
30
40
50
60
70
80
90 100 110 120 130 140
LOAD CURRENT (mA)
LOAD = 10mA
LOAD = 50mA
LOAD = 500mA
1
Figure 12. 5 V In to 15 V Out Efficiency at Various Switching Frequencies with
1:3 Halo Transformer (TGSAD-290V6LF)
Rev. A | Page 10 of 20
0
0
5
10
15
20
25
TIME (ms)
Figure 15. Typical VISO Startup at 5 V In to 5 V Out with
10 mA, 50 mA, and 500 mA Output Load
30
10437-013
fSW = 1MHz
fSW = 700kHz
fSW = 500kHz
fSW = 200kHz
10437-010
EFFICIENCY (%)
70
Data Sheet
ADuM3070
5
5.75
COUT = 47µF, L1 = 47µH
5.25
4.75
VISO (V)
4
VISO (V)
3
4.25
5.75
COUT = 47µF, L1 = 100µH
5.25
4.75
2
4.25
0
5
10
15
20
25
30
TIME (ms)
10437-014
0
ILOAD (A)
LOAD = 10mA
LOAD = 50mA
LOAD = 500mA
1.0
10% LOAD
0.5
0
–2
0
2
4
90% LOAD
6
8
10
12
14
TIME (ms)
Figure 16. Typical VISO Startup at 5 V In to 3.3 V Out with
10 mA, 50 mA, and 500 mA Output Load
10437-017
1
Figure 19. Typical VISO Load Transient Response, 5 V In to 5 V Out at
10% to 90% of 500 mA Load at 500 kHz fSW
5
5.75
COUT = 47µF, L1 = 47µH
5.25
4.75
VISO (V)
4
VISO (V)
3
4.25
5.75
COUT = 47µF, L1 = 100µH
5.25
4.75
2
4.25
0
5
10
15
20
25
30
TIME (ms)
10437-015
0
ILOAD (A)
LOAD = 10mA
LOAD = 50mA
LOAD = 250mA
1.0
10% LOAD
0.5
0
–2
0
2
4
90% LOAD
6
8
10
12
14
TIME (ms)
10437-035
1
Figure 20. Typical VISO Load Transient Response, 5 V In to 5 V Out at
10% to 90% of 500 mA Load at 500 kHz fSW with 0.1 µF Feedback Capacitor
Figure 17. Typical VISO Startup at 3.3 V In to 3.3 V Out with
10 mA, 50 mA, and 250 mA Output Load
18
4.0
COUT = 47µF, L1 = 47µH
3.5
16
3.0
VISO (V)
14
4.0
10
3.5
8
3.0
COUT = 47µF, L1 = 100µH
2.5
4
LOAD = 10mA
LOAD = 20mA
LOAD = 100mA
2
0
0
5
10
15
20
25
TIME (ms)
Figure 18. Typical VISO Startup at 5 V In to 15 V Out with
10 mA, 20 mA, and 100 mA Output Load
30
1.0
10% LOAD
0.5
0
–2
0
2
4
90% LOAD
6
TIME (ms)
8
10
12
14
10437-018
ILOAD (A)
6
10437-016
VISO (V)
12
2.5
Figure 21. Typical VISO Load Transient Load Response, 5 V In to 3.3 V Out at
10% to 90% Load of 500 mA Load at 500 kHz fSW
Rev. A | Page 11 of 20
ADuM3070
4.0
COUT = 47µF, L1 = 100µH
14
12
1.0
0
2
4
6
8
10
12
14
Figure 22. Typical VISO Load Transient Load Response, 5 V In to 3.3 V Out at
10% to 90% Load of 500 mA Load at 500 kHz fSW with 0.1 µF Feedback Capacitor
4.0
VISO (V)
COUT = 47µF, L1 = 100µH
14
12
0
–2
0
2
4
90% LOAD
6
8
10
12
14
Figure 23. Typical VISO Load Transient Response, 3.3 V In to 3.3 V Out at
10% to 90% of 250 mA Load at 500 kHz fSW
4.0
ILOAD (A)
ILOAD (A)
3.0
2.5
1.0
10
12
14
COUT = 47µF, L1 = 100µH
200
10% LOAD
100
0
–2
0
2
4
90% LOAD
6
8
10
12
14
Figure 26. Typical VISO Load Transient Response, 5 V In to 15 V Out at
10% to 90% of 100 mA Load at 500 kHz fSW with 0.1 µF Feedback Capacitor
5.06
3.0
VISO (V)
5.02
2.5
4.98
4.0
COUT = 47µF, L1 = 100µH
3.5
3.0
4.94
2.5
X1 (V)
20
1.0
10% LOAD
0
2
4
90% LOAD
6
TIME (ms)
8
10
12
14
10437-037
0.5
0
–2
8
TIME (ms)
COUT = 47µF, L1 = 47µH
3.5
6
18
16
10437-019
VISO (V)
12
4.0
4
COUT = 47µF, L1 = 47µH
16
14
10% LOAD
2
90% LOAD
Figure 25. Typical VISO Load Transient Response, 5 V In to 15 V Out at
10% to 90% of 100 mA Load at 500 kHz fSW
2.5
0.5
0
18
TIME (ms)
VISO (V)
0
–2
3.0
3.5
10% LOAD
100
TIME (ms)
COUT = 47µF, L1 = 47µH
3.5
200
Figure 24. Typical VISO Load Transient Response, 3.3 V In to 3.3 V Out at
10% to 90% of 250 mA Load at 500 kHz fSW with 0.1 µF Feedback Capacitor
Rev. A | Page 12 of 20
10
0
–2
–1
0
1
TIME (µs)
Figure 27. Typical VISO Output Ripple, 5 V In to 5 V Out at
500 mA Load at 500 kHz fSW
2
10437-021
0
–2
90% LOAD
ILOAD (A)
3.0
2.5
10% LOAD
COUT = 47µF, L1 = 100µH
16
TIME (ms)
ILOAD (A)
18
10437-020
VISO (V)
12
10437-036
VISO (V)
14
2.5
0.5
COUT = 47µF, L1 = 47µH
16
3.0
3.5
ILOAD (A)
18
COUT = 47µF, L1 = 47µH
3.5
10437-038
4.0
Data Sheet
Data Sheet
ADuM3070
15.08
3.36
15.06
VISO (V)
VISO (V)
15.04
3.32
3.28
15.02
15.00
14.98
14.96
3.24
14.94
10
0
–2
–1
0
1
2
TIME (µs)
Figure 28. Typical VISO Output Ripple, 5 V In to 3.3 V Out at
500 mA Load at 500 kHz fSW
VISO (V)
3.32
3.28
3.24
10
0
1
TIME (µs)
2
10437-023
X1 (V)
20
–1
0
–2
–1
0
1
TIME (µs)
Figure 30. Typical VISO Output Ripple, 5 V In to 15 V Out at
100 mA Load at 500 kHz fSW
3.36
0
–2
10
Figure 29. Typical VISO Output Ripple, 3.3 V In to 3.3 V Out at
250 mA Load at 500 kHz fSW
Rev. A | Page 13 of 20
2
10437-024
X1 (V)
20
10437-022
X1 (V)
20
ADuM3070
Data Sheet
APPLICATIONS INFORMATION
A minimum load current of 10 mA is recommended to ensure
optimum load regulation. Smaller loads can generate excess noise
on the output because of short or erratic PWM pulses. Excess
noise generated from smaller loads can cause regulation problems,
in some circumstances.
COUT
47µF
VDD1
R1 + R2
R2
CFB
D2
VDD1
1 X1
16 VREG
2 GND1
15 GND2
3 NC
14 VDD2
VDD1
0.1µF
0.1µF
+5V
13 FB
VFB
5 TP
12 NC
6 TP
11 NC
7 VDDA
10 OC
8 GND1
9 GND2
R2
ROC
100kΩ
10437-025
ADuM3070
4 X2
VISO = VFB × (R1 + R2)/R2
FOR VISO = 3.3V OR 5V CONNECT VREG , VDD2 , AND VISO.
Figure 31. Single Power Supply
L1
47µH
D1
T1
COUT1
47µF
VDD1
CIN
L2
47µH
D2
COUT2
47µF
VISO =
+12V TO
+24V
UNREGULATED
+6V TO
+12V
R1
D3
CFB
D4
VDD1
1 X1
16 VREG
2 GND1
15 GND2
3 NC
APPLICATION SCHEMATICS
V ISO = V FB ×
R1
CIN
4 X2
The ADuM3070 has three main application schematics, as shown
in Figure 31 to Figure 33. Figure 31 has a center-tapped secondary
and two Schottky diodes providing full wave rectification for a
single output, typically for power supplies of 3.3 V, 5 V, 12 V, and
15 V. For single supplies when VISO = 3.3 V or VISO = 5 V, see the
note in Figure 31 about connecting together VREG, VDD2, and VISO.
Figure 32 is a voltage doubling circuit that can be used for a single
supply whose output exceeds 15 V, which is the largest supply that
can be connected to the regulator input, VREG (Pin 16), of the part.
With Figure 32, the output voltage can be as high as 24 V and the
VREG pin is only about 12 V. When using the circuit shown in
Figure 32, to obtain an output voltage lower than 10 V (for
example, VDD1 = 3.3 V, VISO = 5 V), connect VREG to VISO directly.
Figure 33, which also uses a voltage doubling secondary circuit,
is shown as an example of a coarsely regulated, positive power
supply and an unregulated, negative power supply for outputs of
approximately ±5 V, ±12 V, and ±15 V. For any circuit in Figure 31,
Figure 32, or Figure 33, the isolated output voltage (VISO) can be
set using the voltage dividers, R1 and R2 (values 1 kΩ to 100 kΩ),
using the following equation:
VISO =
+3.3V
TO +15V
VDD1
0.1µF
ADuM3070
0.1µF
+5V
14 VDD2
13 FB
5 TP
12 NC
VFB
R2
6 TP
11 NC
7 VDDA
10 OC
8 GND1
9 GND2
ROC
100kΩ
VISO = VFB × (R1 + R2)/R2
FOR VISO = 15V OR LESS, VREG CAN CONNECT TO VISO.
Figure 32. Doubling Power Supply
L1
47µH
D1
T1
VISO =
COARSELY
REGULATED
+5V TO 15V
COUT1
47µF
VDD1
CIN
L2
47µH
D2
COUT2
47µF
UNREGULATED
–5V TO –15V
D3
R1
CFB
D4
VDD1
1 X1
16 VREG
2 GND1
15 GND2
3 NC
ADuM3070
4 X2
13 FB
0.1µF
+5V
VFB
12 NC
5 TP
VDD1
0.1µF
14 VDD2
6 TP
11 NC
7 VDDA
10 OC
8 GND1
9 GND2
ROC
100kΩ
R2
VISO = VFB × (R1 + R2)R2
Figure 33. Positive and Unregulated Negative Supply
where VFB is the internal feedback voltage, which is
approximately 1.25 V.
Rev. A | Page 14 of 20
10437-027
The ADuM3070 implements undervoltage lockout (UVLO) with
hysteresis on the VDD1 power input. This feature ensures that the
converter does enter oscillation due to noisy input power or slow
power-on ramp rates.
L1
47µH
D1
T1
10437-026
The dc-to-dc converter section of the ADuM3070 uses a secondary
side controller architecture with isolated pulse-width modulation
(PWM) feedback. VDD1 power is supplied to an oscillating circuit
that switches current to the primary side of an external power
transformer using internal push-pull switches at the X1 and X2
pins. Power transferred to the secondary side of the transformer
is full-wave rectified with external Schottky diodes (D1 and D2),
filtered with the L1 inductor and COUT capacitor, and regulated
to the isolated power supply voltage from 3.3 V to 15 V. The
secondary (VISO) side controller regulates the output by using a
feedback voltage VFB from a resistor divider on the output and
creating a PWM control signal that is sent to the primary (VCC)
side by a dedicated iCoupler data channel labeled VFB. The primary
side PWM converter varies the duty cycle of the X1 and X2 switches
to modulate the oscillator circuit and control the power being
sent to the secondary side. This feedback allows for significantly
higher power and efficiency.
Data Sheet
ADuM3070
TRANSFORMER DESIGN
Transformers have been designed for use in the circuits shown
in Figure 31, Figure 32, and Figure 33 and are listed in Table 13.
The design of a transformer for the ADuM3070 can differ from
some isolated dc-to-dc converter designs that do not regulate the
output voltage. The output voltage is regulated by a PWM controller
in the ADuM3070 that varies the duty cycle of the primary side
switches in response to a secondary side feedback voltage, VFB,
received through an isolated digital channel. The internal
controller has a limit of 40% maximum duty cycle.
TRANSFORMER TURNS RATIO
To determine the transformer turns ratio, and taking into
account the losses for the primary switches and the losses for
the secondary diodes and inductors, the external transformer
turns ratio for the ADuM3070 can be calculated by
NS
VISO + VD
=
N P VDD1 (MIN) × D × 2
where:
NS/NP is the primary to secondary turns ratio.
VISO is the isolated output supply voltage.
VD is the Schottky diode voltage drop (0.5 V maximum).
VDD1 (MIN) is the minimum input supply voltage.
D is the duty cycle = 0.30 for a 30% typical duty cycle, 40% is
maximum, and a multiplier factor of 2 is used for the push-pull
switching cycle.
For Figure 33, the circuit also uses double windings and diode pairs
to create a doubler circuit; however, because a positive and negative
output voltage is created, VISO is used in the equation.
NS
VISO + VD
=
N P VDD1 (MIN) × D × 2
where:
NS/NP is the primary to secondary turns ratio.
VISO is the isolated output supply voltage and is used in the equation
because the circuit uses two pairs of diodes creating a doubler
circuit with a positive and negative output.
VD is the Schottky diode voltage drop (0.5 V maximum).
VDD1 (MIN) is the minimum input supply voltage, and a multiplier
factor of 2 is used for the push-pull switching cycle.
D is the duty cycle; in this case, a higher duty cycle of D = 0.35
for a 35% typical duty cycle (40% maximum duty cycle) was
used in the Figure 33 circuit to reduce the maximum voltages
seen by the diodes for a ±15 V supply.
For Figure 33, the +5 V to ±15 V reference design in Table 13,
with VDD1 (MIN) = 4.5 V, results in a turns ratio of NS/NP = 5.
TRANSFORMER ET CONSTANT
The next transformer design factor to consider is the ET constant.
This constant determines the minimum V × µs constant of
the transformer over the operating temperature. ET values of
14 V × µs and 18 V × µs were selected for the ADuM3070 designs
listed in Table 13 using the following equation:
For Figure 31, the 5 V to 5 V reference design in Table 13, with
VDD1 (MIN) = 4.5 V, the turns ratio is NS/NP = 2.
ET ( MIN ) =
For a similar 3.3 V input to 3.3 V output, isolated single power
supply and with VDD1 (MIN) = 3.0 V, the turns ratio is also NS/NP =
2. Therefore, the same transformer turns ratio NS/NP = 2 can be
used for the three single power applications (5 V to 5 V, 5 V to
3.3 V, and 3.3 V to 3.3 V).
For Figure 32, the circuit uses double windings and diode pairs
to create a doubler circuit; therefore, half the output voltage, VISO/2,
is used in the equation.
VISO
+ VD
NS
2
=
N P VDD1 (MIN) × D × 2
NS/NP is the primary to secondary turns ratio.
VISO/2 is used in the equation because the circuit uses two pairs
of diodes creating a doubler circuit.
VD is the Schottky diode voltage drop (0.5 V maximum).
VDD1 (MIN) is the minimum input supply voltage.
D is the duty cycle, which is 0.30 for a 30% typical duty cycle and
0.40 for a 40% maximum duty cycle, and a multiplier factor of
two is used for the push-pull switching cycle.
For Figure 32, the 5 V to 15 V reference design in Table 13, with
VDD1 (MIN) = 4.5 V, results in a turns ratio of NS/NP = 3.
VDD1 (MAX)
f SW ( MIN ) × 2
where:
VDD1 (MAX) is the maximum input supply voltage.
fSW (MIN) is the minimum primary switching frequency = 300 kHz
in startup, and a multiplier factor of 2 is used for the push-pull
switching cycle.
TRANSFORMER PRIMARY INDUCTANCE AND
RESISTANCE
Another important characteristic of the transformer for designs
with the ADuM3070 is the primary inductance. Transformers
for the ADuM3070 are recommended to have between 60 µH
to 100 µH of inductance per primary winding. Values of primary
inductance in this range are needed for smooth operation of the
ADuM3070 pulse-by-pulse current-limit circuit, which can help
protect against build up of saturation currents in the transformer. If
the inductance is specified for the total of both primary windings,
for example, as 400 µH, the inductance of one winding is ¼ of two
equal windings, or 100 µH.
Another important characteristic of the transformer for designs
with the ADuM3070 is primary resistance. Primary resistance as
low as is practical (less than 1 Ω) helps reduce losses and improves
efficiency. The total primary resistance can be measured and
specified, and is shown for the transformers in Table 13.
Rev. A | Page 15 of 20
ADuM3070
Data Sheet
Table 13. Transformer Reference Designs
Part No.
JA4631-BL
JA4650-BL
KA4976-AL
TGSAD-260V6LF
TGSAD-290V6LF
TGSAD-292V6LF
TGAD-260NARL
TGAD-290NARL
TGAD-292NARL
Manufacturer
Coilcraft
Coilcraft
Coilcraft
Halo Electronics
Halo Electronics
Halo Electronics
Halo Electronics
Halo Electronics
Halo Electronics
Turns Ratio,
PRI:SEC
1CT:2CT
1CT:3CT
1CT:5CT
1CT:2CT
1CT:3CT
1CT:5CT
1CT:2CT
1CT:3CT
1CT:5CT
ET Constant
(V × µs Min)
18
18
18
14
14
14
14
14
14
Total Primary
Inductance (µH)
255
255
255
389
389
389
389
389
389
TRANSFORMER ISOLATION VOLTAGE
Isolation voltage and isolation type should be determined for
the requirements of the application and then specified. The
transformers in Table 13 have been specified for 2500 V rms for
supplemental or basic isolation and for 1500 V rms for functional
isolation. Other isolation levels and isolation voltages can be
specified and requested from the manufacturers that are listed
in Table 13 or from other manufacturers.
SWITCHING FREQUENCY
The ADuM3070 switching frequency can be adjusted from
200 kHz to 1 MHz by changing the value of the ROC resistor
shown in Figure 31, Figure 32, and Figure 33. The value of the
ROC resistor needed for the desired switching frequency can be
determined from the switching frequency vs. ROC resistance
curve shown in Figure 4. The output filter inductor value and
output capacitor value for the ADuM3070 application schematics
have been designed to be stable over the switching frequency
range from 500 kHz to 1 MHz, when loaded from 10% to 90%
of the maximum load.
The ADuM3070 also has an open-loop mode where the output
voltage is not regulated and is dependent on the transformer
turns ratio, NS/NP, and the conditions of the output including
output load current and the losses in the dc-to-dc converter
circuit. This open-loop mode is selected when the OC pin is
connected high to the VDD2 pin. In open-loop mode, the
switching frequency is 318 kHz.
TRANSIENT RESPONSE
The load transient response of the output voltage of the ADuM3070
for 10% to 90% of the full load is shown in Figure 19 to Figure 26
for the application schematics in Figure 31 and Figure 32. The
response shown is slow but stable and can have more output
change than desired for some applications. The output voltage
change with load transient has been reduced, and the output has
been shown to remain stable by adding more inductance to the
output circuits, as shown in the second VISO output waveform in
Figure 19 to Figure 26.
Total Primary
Resistance (Ω)
0.2
0.2
0.2
0.8
0.8
0.8
0.8
0.8
0.8
Isolation
Voltage (rms)
2500
2500
2500
2500
2500
2500
1500
1500
1500
Isolation
Type
Basic
Basic
Basic
Supplemental
Supplemental
Supplemental
Functional
Functional
Functional
Reference
Figure 31
Figure 32
Figure 33
Figure 31
Figure 32
Figure 33
Figure 31
Figure 32
Figure 33
For additional improvement in transient response, add a 0.1 µF
ceramic capacitor (CFB) in parallel with the high feedback resistor.
As shown in Figure 19 to Figure 26, this value helps reduce the
overshoot and undershoot during load transients.
COMPONENT SELECTION
Power supply bypassing is required at the input and output supply
pins. Note that a low ESR ceramic bypass capacitor of 0.1 µF is
required on Side 1 between Pin 7 and Pin 8, and on Side 2 between
Pin 14 and Pin 15, as close to the chip pads as possible.
The power supply section of the ADuM3070 uses a high oscillator
frequency to efficiently pass power through the external power
transformer. Bypass capacitors are required for several operating
frequencies. Noise suppression requires a low inductance, high
frequency capacitor; ripple suppression and proper regulation
require a large value capacitor. To suppress noise and reduce ripple,
large valued ceramic capacitors of X5R or X7R dielectric type are
recommended. The recommended capacitor value is 10 µF for
VDD1 and 47 µF for VISO. These capacitors have a low ESR and are
available in moderate 1206 or 1210 sizes for voltages up to 10 V. For
output voltages larger than 10 V, two 22 µF ceramic capacitors can
be used in parallel. See Table 14 for recommended components.
Inductors must be selected based on the value and supply current
needed. Most applications with switching frequencies between
500 kHz and 1 MHz and load transients between 10% and 90%
of full load are stable with the 47 µH inductor value listed in Table 14.
Values as large as 200 µH can be used for power supply applications
with a switching frequency as low as 200 kHz to help stabilize the
output voltage or for improved load transient response (see Figure 19
to Figure 26). Inductors in a small 1212 or 1210 size are listed in
Table 14 with a 47 µH value and a 0.41 A current rating to handle the
majority of applications below a 400 mA load, and with a 100 µH
value and a 0.34 A current rating to handle a load to 300 mA.
Schottky diodes are recommended for their low forward voltage
to reduce losses and their high reverse voltage of up to 40 V to
withstand the peak voltages available in the doubling circuit
shown in Figure 32 and Figure 33.
Rev. A | Page 16 of 20
Data Sheet
ADuM3070
The board layout shows enlarged pads for the GNDx pins (Pin 2
and Pin 8) on Side 1 and (Pin 9 and Pin 15) on Side 2. Implement
large diameter vias from the pad to the ground planes and power
planes to increase thermal conductivity and to reduce inductance.
Multiple vias in the thermal pads can significantly reduce
temperatures inside the chip. The dimensions of the expanded
pads are left to the discretion of the designer and the available
board space.
Table 14. Recommended Components
Part Number
GRM32ER71A476KE15L
Manufacturer
Murata
GRM32ER71C226KEA8L
Murata
GRM31CR71A106KA01L
Murata
MBR0540T1/D
ON Semiconductor
LQH3NPN470MM0
Murata
ME3220-104KL
Coilcraft
Value
47 μF, 10 V, X7R,
1210
22 μF, 16 V, X7R,
1210
10 μF, 10 V, X7R,
1206
0.5 A, 40 V,
Schottky, SOD-123
47 μH, 0.41 A,
1212
100 μH, 0.34 A,
1210
THERMAL ANALYSIS
The ADuM3070 parts consist of two internal die attached to a
split lead frame with two die attach paddles. For the purposes of
thermal analysis, the die is treated as a thermal unit, with the
highest junction temperature reflected in the θJA from Table 5.
The value of θJA is based on measurements taken with the devices
mounted on a JEDEC standard, 4-layer board with fine width traces
and still air. Under normal operating conditions, the ADuM3070
devices operate at full load across the full temperature range
without derating the output current. However, following the
recommendations in the Printed Circuit Board (PCB) Layout
section decreases thermal resistance to the PCB, allowing increased
thermal margins in high ambient temperatures. The ADuM3070
has a thermal shutdown circuit that shuts down the dc-to-dc
converter of the ADuM3070 when a die temperature of about
160°C is reached. When the die cools below about 140°C, the
ADuM3070 dc-to-dc converter turns on again.
PRINTED CIRCUIT BOARD (PCB) LAYOUT
Note that the total lead length between the ends of the low ESR
capacitor and the VDDx and GNDx pins must not exceed 2 mm. See
Figure 34 for the recommended PCB layout.
VREG
X1
GND2
VDD2
NC
FB
X2
TP
NC
TP
NC
VDDA
OC
GND1
GND2
10437-028
Figure 34. Recommended PCB Layout
POWER CONSUMPTION
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 specified in Table 10,
thereby leading to latch-up and/or permanent damage.
The total input supply current is equal to the sum of the IDD1 primary
transformer current and the ADuM3070 input current, IDDA.
The following relationship allows the total IIN current to be:
IIN = (IISO × VISO)/(E × VDD1)
The ADuM3070 is a power device that dissipates about 1 W of
power when fully loaded. Because it is not possible to apply a
heat sink to an isolation device, the device primarily depends on
heat dissipation into the PCB through the GNDx pins. If the device
is used at high ambient temperatures, care must be taken to provide
a thermal path from the GNDx pins to the PCB ground plane.
IIN
VDD1
VISO IISO
IDD1
RECT
X1
X2
VREG
ADuM3070
REG
VDDA
IDDA
SECONDARY
CONTROLLER
INTERNAL
FEEDBACK
GND1
VDD2
5V
PRIMARY
CONVERTER/
DRIVER
(1)
where:
IIN is the total supply input current.
IISO is the current drawn by the secondary side external load.
E is the power supply efficiency at the given output load from
Figure 8 or Figure 14 at the VISO and VDD1 condition of interest.
FB
OC
GND2
NOTES
1. VDD1 IS THE POWER SUPPLY FOR THE PUSH-PULL TRANSFORMER.
2. VDDA IS THE POWER SUPPLY OF SIDE 1 OF THE ADuM3070.
Figure 35. Supply Currents
Rev. A | Page 17 of 20
10437-029
GND1
ADuM3070
Data Sheet
POWER CONSIDERATIONS
Soft Start Mode and Current-Limit Protection
When the ADuM3070 first receives power from VDD1, it is
in soft start mode, and the output voltage, VISO, is increased
gradually while it is below the startup threshold. In soft start
mode, to limit the peak current during VISO power-up, the
primary converter gradually increases the width of the PWM
signal. When the output voltage is larger than the start-up
threshold, the PWM signal can be transferred from the secondary
controller to the primary converter, and the dc-to-dc converter
switches from soft start mode to the normal PWM control mode.
If a short circuit occurs, the push-pull converter shuts down for
about 2 ms and then enters soft start mode. If, at the end of soft
start, a short circuit still exists, the process is repeated, which is
called hiccup mode. If the short circuit is cleared, the ADuM3070
enters normal operation.
The ADuM3070 has a pulse-by-pulse current limit, which is
active at startup and during normal operation, that protects the
primary switches, X1 and X2, from exceeding approximately
1.3 A peak, protecting the transformer windings.
The insulation lifetime of the ADuM3070 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, dc, or unipolar ac. 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
voltages listed in Table 11 can be applied while maintaining the
50-year minimum lifetime, if the voltage conforms to either the
unipolar ac or dc voltage cases. Treat any cross-insulation voltage
waveform that does not conform to Figure 37 or Figure 38 as a
bipolar ac waveform, and limit its peak voltage to the 50-year
lifetime voltage value listed in Table 11.
10437-030
RATED PEAK VOLTAGE
0V
INSULATION LIFETIME
Figure 36. Bipolar AC Waveform
RATED PEAK VOLTAGE
10437-031
0V
Figure 37. DC Waveform
RATED PEAK VOLTAGE
0V
NOTES
1. THE VOLTAGE IS SHOWN SINUSOIDAL
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.
Figure 38. Unipolar AC Waveform
Rev. A | Page 18 of 20
10437-032
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, Inc.,
conducts an extensive set of evaluations to determine the lifetime of
the insulation structure within the ADuM3070. 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 11 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.
Data Sheet
ADuM3070
OUTLINE DIMENSIONS
0.197 (5.00)
0.193 (4.90)
0.189 (4.80)
9
1
8
0.244 (6.20)
0.236 (5.99)
0.228 (5.79)
0.010 (0.25)
0.006 (0.15)
0.069 (1.75)
0.053 (1.35)
0.065 (1.65)
0.049 (1.25)
0.010 (0.25)
0.004 (0.10)
COPLANARITY
0.004 (0.10)
0.158 (4.01)
0.154 (3.91)
0.150 (3.81)
0.025 (0.64)
BSC
SEATING
PLANE
0.012 (0.30)
0.008 (0.20)
8°
0°
0.020 (0.51)
0.010 (0.25)
0.050 (1.27)
0.016 (0.41)
COMPLIANT TO JEDEC STANDARDS MO-137-AB
CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
0.041 (1.04)
REF
01-28-2008-A
16
Figure 39. 16-Lead Shrink Small Outline Package [QSOP]
(RQ-16)
Dimension shown in inches and (millimeters)
ORDERING GUIDE
Model 1, 2
ADuM3070ARQZ
EVAL-ADuM3070EBZ
1
2
Temperature Range
−40°C to +105°C
Package Description
16-Lead Shrink Small Outline Package [QSOP]
Evaluation Board
Tape and reel are available. The addition of an -RL7 suffix designates a 7” (1000 units) tape and reel option.
Z = RoHS Compliant Part.
Rev. A | Page 19 of 20
Package Option
RQ-16
ADuM3070
Data Sheet
NOTES
©2012–2014 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D10437-0-5/14(A)
Rev. A | Page 20 of 20
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