Datasheet

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Isolated Switching Regulator

with Integrated Feedback

Data Sheet

ADuM4070

Rev. 0 Document Feedback

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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 70% efficiency

200 kHz to 1 MHz adjustable oscillator

Soft start function at power-up

Pulse-by-pulse overcurrent protection

Thermal shutdown

5000 V rms isolation

High common-mode transient immunity: >25 kV/μs

16-lead SOIC package with 8.3 mm creepage

High temperature operation: 105°C maximum

Safety and regulatory approvals (pending)

UL recognition: 5000 V rms for 1 minute per UL 1577

CSA Component Acceptance Notice #5A

VDE certificate of conformity

DIN V VDE V 0884-10 (VDE V 0884-10):2006-12

IORM

= 849 V peak

APPLICATIONS

Power supply start-up bias and gate drives

Isolated sensor interfaces

Process controls

FUNCTIONAL BLOCK DIAGRAM

ADuM4070

PRIMARY

CONTROLLER/

DRIVER

INTERNAL

FEEDBACK

DD2

REG

DD1

DDA

X2X1

GND

10461-001

ISO

REGULATOR

RECTIFIER

SECONDARY

CONTROLLER

Figure 1.

GENERAL DESCRIPTION

The ADuM4070

is a regulated dc-to-dc isolated power supply

controller with an internal MOSFET driver. The dc-to-dc controller

has internal isolated PWM feedback from the secondary side based

on the iCoupler® chip scale transformer technology and complete

loop compensation. This architecture eliminates the need to use

an optocoupler for feedback and compensates the loop for stability.

The ADuM4070 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 wide-body SOIC package provide a solution with a smaller

form factor and 8.3 mm creepage distance.

The regulated feedback provides a relatively flat efficiency curve

over the full output power range. The ADuM4070 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 7,075,329. Other patents pending.

Summary of content (20 pages)

PAGE 1
Isolated Switching Regulator with Integrated Feedback ADuM4070 Data Sheet FEATURES FUNCTIONAL BLOCK DIAGRAM VDD1 VISO RECTIFIER X1 VREG X2 ADuM4070 REGULATOR VDD2 5V VDDA PRIMARY CONTROLLER/ DRIVER SECONDARY CONTROLLER OC INTERNAL FEEDBACK GND1 FB GND2 10461-001 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.
PAGE 2
ADuM4070 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Pin Configuration and Function Descriptions..............................8 Applications ....................................................................................... 1 Typical Performance Characteristics ..............................................9 Functional Block Diagram ..............................................................
PAGE 3
Data Sheet ADuM4070 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.
PAGE 4
ADuM4070 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.
PAGE 5
Data Sheet ADuM4070 PACKAGE CHARACTERISTICS Table 5. Parameter RESISTANCE AND CAPACITANCE Resistance (Input to Output) 1 Capacitance (Input to Output)1 IC Junction to Ambient Thermal Resistance THERMAL SHUTDOWN Thermal Shutdown Threshold Thermal Shutdown Hysteresis 1 2 Symbol Min Typ Max Unit RI-O CI-O θJA 1012 2.
PAGE 6
ADuM4070 Data Sheet DIN V VDE V 0884-10 (VDE V 0884-10):2006-12 INSULATION CHARACTERISTICS This isolator is suitable for reinforced electrical isolation only within the safety limit data. Protective circuits ensure maintenance of the safety data. The asterisk (*) marking branded on the component denotes DIN V VDE V 0884-10 (VDE V 0884-10):2006-12 approval. Table 8.
PAGE 7
Data Sheet ADuM4070 ABSOLUTE MAXIMUM RATINGS Ambient temperature = 25°C, unless otherwise noted. 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. Table 10.
PAGE 8
ADuM4070 Data Sheet PIN CONFIGURATION AND FUNCTION DESCRIPTIONS X1 1 16 VREG *GND1 2 NC 3 15 GND2* ADuM4070 14 VDD2 TOP VIEW 13 FB NC 5 (Not to Scale) 12 NC X2 4 NC 6 VDDA 7 *GND1 8 11 NC 10 OC 9 GND2* *PIN 2 AND PIN 8 ARE INTERNALLY CONNECTED; IT IS RECOMMENDED THAT BOTH PINS BE CONNECTED TO A COMMON GROUND. PIN 9 AND PIN 15 ARE INTERNALLY CONNECTED; IT IS RECOMMENDED THAT BOTH PINS BE CONNECTED TO A COMMON GROUND. 10461-003 NOTES 1. NC = NO CONNECT. DO NOT CONNECT TO THIS PIN. Figure 3.
PAGE 9
Data Sheet ADuM4070 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 (kΩ) 0 80 80 70 70 60 60 EFFICIENCY (%) 90 50 40 30 fSW = 1MHz fSW = 700kHz fSW = 500kHz fSW = 200kHz 0 0 50 100 150 200 250 300 350 400 450 150 200 250 300 350 400 450 500 500 LOAD CURRENT (mA) 50 40 30 20
PAGE 10
ADuM4070 Data Sheet 70 90 80 60 70 EFFICIENCY (%) EFFICIENCY (%) 50 40 30 60 50 40 30 20 20 25 50 75 100 125 150 175 200 LOAD CURRENT (mA) 0 10461-010 0 0 Figure 10. Typical Efficiency over Temperature with 1:3 Coilcraft Transformer (CR7984-CL), fSW = 500 kHz, 3.3 V Input to 5 V Output 0 20 30 40 50 60 70 80 90 100 110 120 130 140 Figure 13.
PAGE 11
Data Sheet ADuM4070 6 18 16 5 14 12 VISO (V) VISO (V) 4 3 10 8 6 2 4 5 10 15 20 25 30 TIME (ms) 0 10461-015 0 0 LOAD = 10mA LOAD = 20mA LOAD = 100mA 2 Figure 15. Typical VISO Startup with 10 mA, 50 mA, and 500 mA Output Load, 5 V Input to 5 V Output 0 5 10 15 20 25 30 TIME (ms) 10461-018 LOAD = 10mA LOAD = 50mA LOAD = 500mA 1 Figure 18. Typical VISO Startup with 10 mA, 20 mA, and 100 mA Output Load, 5 V Input to 15 V Output 5 5.75 COUT = 47µF, L1 = 47µH 5.25 4.
PAGE 12
ADuM4070 COUT = 47µF, L1 = 100µH 3.0 2.5 2.5 1.0 0 –2 0 2 4 90% LOAD 6 8 10 12 14 Figure 21. Typical VISO Load Transient Response at 10% to 90% of 500 mA Load, fSW = 500 kHz, 5 V Input to 3.3 V Output 4.0 12 VISO (V) 14 COUT = 47µF, L1 = 100µH 14 2.5 12 0 –2 0 2 4 90% LOAD 6 8 10 12 14 TIME (ms) Figure 22. Typical VISO Load Transient Response at 10% to 90% of 500 mA Load with 0.1 µF Feedback Capacitor, fSW = 500 kHz, 5 V Input to 3.3 V Output ILOAD (A) 3.
PAGE 13
Data Sheet ADuM4070 5.06 3.36 3.32 3.28 4.94 3.24 20 20 10 0 –2 –1 0 1 2 TIME (ms) 10 0 –2 –1 0 1 2 TIME (ms) 10461-026 X1 (V) 4.98 10461-024 X1 (V) VISO (V) VISO (V) 5.02 Figure 29. Typical VISO Output Voltage Ripple at 250 mA Load, fSW = 500 kHz, 3.3 V Input to 3.3 V Output Figure 27. Typical VISO Output Voltage Ripple at 500 mA Load, fSW = 500 kHz, 5 V Input to 5 V Output 15.08 3.36 15.06 VISO (V) VISO (V) 15.04 3.32 3.28 15.02 15.00 14.
PAGE 14
ADuM4070 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 in this way can cause regulation problems in some circumstances. COUT 47µF VDD1 D2 VDD1 1 X1 16 VREG 2 GND1 15 GND2 3 NC ADuM4070 4 X2 VDD1 0.1µF 12 NC 6 NC 11 NC 7 VDDA 10 OC 8 GND1 9 GND2 VFB R2 ROC 100kΩ VISO = VFB × (R1 + R2)/R2 FOR VISO = 3.
PAGE 15
Data Sheet ADuM4070 TRANSFORMER DESIGN Custom transformers were designed for use in the circuits shown in Figure 31, Figure 32, and Figure 33 (see Table 13). The transformers designed for use with the ADuM4070 differ from other transformers used with isolated dc-to-dc converters that do not regulate the output voltage.
PAGE 16
ADuM4070 Data Sheet TRANSFORMER PRIMARY INDUCTANCE AND RESISTANCE Another important characteristic of the transformer for designs with the ADuM4070 is the primary inductance. Transformers for the ADuM4070 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 ADuM4070 pulse-by-pulse current-limit circuit, which can help protect against a build-up of saturation currents in the transformer.
PAGE 17
Data Sheet ADuM4070 PRINTED CIRCUIT BOARD (PCB) LAYOUT Figure 34 shows the recommended PCB layout for the ADuM4070. 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. VREG The total input supply current is equal to the sum of the IDD1 primary transformer current and the ADuM4070 input current, IDDA (see Figure 35).
PAGE 18
ADuM4070 Data Sheet The voltage presented in Figure 37 is shown as sinusoidal for illustration purposes only. It is meant to represent any voltage waveform varying between 0 V and some limiting value. The limiting value can be positive or negative, but the voltage cannot cross 0 V. The insulation lifetime of the ADuM4070 depends on the voltage waveform type imposed across the isolation barrier.
PAGE 19
Data Sheet ADuM4070 OUTLINE DIMENSIONS 12.85 12.75 12.65 1.93 REF 16 9 7.60 7.50 7.40 10.51 10.31 10.11 8 2.64 2.54 2.44 2.44 2.24 0.30 0.20 0.10 COPLANARITY 0.1 0.71 0.50 0.31 0.25 BSC GAGE PLANE 45° SEATING PLANE 1.27 BSC 1.01 0.76 0.51 0.46 0.36 COMPLIANT TO JEDEC STANDARDS MS-013-AC 0.32 0.23 8° 0° 11-15-2011-A 1 PIN 1 MARK Figure 39.