FEATURES 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 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 Data Sheet Isolated Switching Regulator With Integrated Feedback ADuM3070 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. 0 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©2012 Analog Devices, Inc. All rights reserved. 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 5/12—Revision 0: Initial Version Rev. 0 | 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. 0 | 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 10 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. 0 | 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. 0 | 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. 0 | 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. 0 | 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. 0 | Page 8 of 20 Data Sheet ADuM3070 TYPICAL PERFORMANCE CHARACTERISTICS 90 1500 1400 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 Figure 6. Typical Efficiency at 5 V In to 5 V Out at Various Switching Frequencies with 1:2 Halo Transformer (TGSAD-260V6LF) 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) Rev. 0 | 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 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. 0 | 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 20 10437-010 EFFICIENCY (%) 70 Data Sheet ADuM3070 5.75 5 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 4 6 8 10 12 14 TIME (ms) 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 4.0 18 COUT = 47µF, L1 = 47µH 3.5 16 3.0 VISO (V) 14 12 10 2.5 4.0 COUT = 47µF, L1 = 100µH 3.5 3.0 8 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) 2 90% LOAD 10437-035 1 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. 0 | Page 11 of 20 ADuM3070 4.0 COUT = 47µF, L1 = 100µH 14 2.5 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 2.5 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 1.0 10 12 14 COUT = 47µF, L1 = 100µH 200 0 –2 90% LOAD 10% LOAD 100 0 2 4 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 0 2 4 90% LOAD 6 TIME (ms) 8 10 12 14 10437-037 10% LOAD 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. 0 | 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 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. 0 | 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 V ISO 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 R1 + R2 = V FB × R2 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 VDD1 0.1µF 14 VDD2 13 FB 5 TP 12 NC 6 TP 11 NC 7 VDDA 10 OC 8 GND1 9 GND2 0.1µF +5V VFB 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. 0 | 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. 0 | 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. 0 | 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 POWER CONSUMPTION Figure 34. Recommended PCB Layout In applications involving high common-mode transients, ensure that board coupling across the isolation barrier is minimized. Furthermore, design the board layout such that any coupling that does occur equally affects all pins on a given component side. Failure to ensure this can cause voltage differentials between pins, exceeding the absolute maximum ratings 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. 0 | 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. 0 | 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. 0 | Page 19 of 20 Package Option RQ-16 ADuM3070 Data Sheet NOTES ©2012 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D10437-0-5/12(0) Rev. 0 | Page 20 of 20