Constant-Frequency, Current-Mode Step-Up DC-to-DC Controller Data Sheet ADP1621 FEATURES TYPICAL APPLICATION CIRCUIT V = 3.3V IN 92% efficiency (no sense resistor required) 1.0% initial accuracy L1 4.7H IC supply voltage range: 2.9 V to 5.5 V V = 5V OUT D1 1A Power-input voltage as low as 1.0 V C3 C4 PIN IN Capable of high supply input voltage (>5.5 V) R1 1F 0.1F R S 35.7k 10V 10V 80 1% C C C with an external NPN or a resistor OUT1 OUT2 OUT3 1F 10F 150F CS 10V 10V 6.3V V UVLO and 35 mA shunt regulator IN ADP1621 2 R2 11.5k External slope compensation with 1 resistor SDSN 1% M1 GATE Programmable operating frequency COMP PGND (100 kHz to 1.5 MHz) with 1 resistor R COMP FREQ Lossless current sensing for switch-node voltage <30 V 9.09k FB C2 GND C1 120pF Resistor current sensing for switch-node voltage >30 V C 47F COMP 6.3V 1.8nF R FREQ Synchronizable to external clock 31.6k 1% Current-mode operation for excellent line and load transient AGND responses f = 600kHz OSC 10 A shutdown current C1 = MURATA GRM31CR60J476M M1 = VISHAY Si7882DP C = SANYO POSCAP 6TPE150M D1 = VISHAY SSA33L OUT3 Current limit and thermal overload protection L1 = TOKO FDV0630-4R7M Figure 1. High Efficiency Output Boost Converter in Lossless Mode, Soft start in 2048 clock cycles 3.3 V Input, 5 V Output (Bootstrapped) Supported by ADIsimPower design tool The ADP1621 supply input voltage range is 2.9 V to 5.5 V, although higher input voltages are possible with the use of a APPLICATIONS small signal NPN pass transistor or a single resistor. The voltage APD bias of the power input can be as low as 1 V for fuel cell applications. Portable electronic equipment The switching frequency is set by an external resistor over a range Isolated dc-to-dc converter of 100 kHz to 1.5 MHz and can be synchronized to an external Step-up/step-down dc-to-dc converter clock by using the SDSN pin. The shutdown quiescent current is LED driver for laptop computer and navigation system less than 10 A. The ADP1621 has a thermal shutdown feature LCD backlighting that shuts down the gate driver when the junction temperature GENERAL DESCRIPTION reaches approximately 150C. The internal soft start circuit limits The ADP1621 is a fixed-frequency, pulse-width modulation inrush current at startup. The ADP1621 is available in the 10-lead (PWM), current-mode, step-up converter controller. It drives an MSOP lead-free package and is specified over the 40C to +125C external n-channel MOSFET to convert the input voltage to a junction temperature range. 100 higher output voltage. The ADP1621 can also be used to drive flyback, SEPIC, and forward converter topologies, either isolated 90 or nonisolated. 80 The ADP1621 eliminates the use of a current-sense power resistor by measuring the voltage drop across the on resistance of 70 the n-channel MOSFET. This technique, allowed up to a maximum voltage of 30 V at the switch node, maximizes 60 efficiency and reduces cost. For switch-node voltages higher than 50 30 V or for more accurate current limiting, the CS pin can be connected to a current-sense resistor in the source of the MOSFET. 40 The slope compensation is implemented by an external resistor, 30 allowing a wide range of external components (inductors and 0.01 0.1 1 10 MOSFETs), and can be chosen for various switching frequencies LOAD CURRENT (A) Figure 2. Efficiency of Circuit Shown in Figure 1 and input and output voltages. Rev. D Document Feedback 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 One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No Tel: 781.329.4700 20062016 Analog Devices, Inc. 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EFFICIENCY (%) 06090-042 06090-001ADP1621 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Duty Cycle ................................................................................... 14 Applications ....................................................................................... 1 Setting the Output Voltage ........................................................ 14 General Description ......................................................................... 1 Inductor Current Ripple ............................................................ 14 Typical Application Circuit ............................................................. 1 Inductor Selection ...................................................................... 14 Revision History ............................................................................... 2 Input Capacitor Selection .......................................................... 15 Simplified Block Diagram ............................................................... 3 Output Capacitor Selection ....................................................... 15 Specifications ..................................................................................... 4 Diode Selection ........................................................................... 16 Absolute Maximum Ratings ............................................................ 6 MOSFET Selection ..................................................................... 16 Thermal Resistance ...................................................................... 6 Loop Compensation .................................................................. 17 ESD Caution .................................................................................. 6 Slope Compensation .................................................................. 18 Pin Configuration and Function Descriptions ............................. 7 Current Limit .............................................................................. 18 Typical Performance Characteristics ............................................. 8 Light Load Operation ................................................................ 19 Theory of Operation ...................................................................... 12 Recommended Component Manufacturers ........................... 19 Control Loop ............................................................................... 12 Layout Considerations ................................................................... 20 Current-Sense Configurations .................................................. 12 Efficiency Considerations ............................................................. 21 Current Limit .............................................................................. 13 Examples of Application Circuits ................................................. 22 Undervoltage Lockout ............................................................... 13 Standard Boost ConverterDesign Example ........................ 22 Shutdown ..................................................................................... 13 Bootstrapped Boost Converter ................................................. 23 Soft Start ...................................................................................... 13 SEPIC Converter Circuit ........................................................... 27 Internal Shunt Regulators .......................................................... 13 Low Voltage Power-Input Circuit ............................................ 27 Setting the Oscillator Frequency and Synchronization LED Driver Application Circuits ............................................. 28 Frequency .................................................................................... 13 Related Devices ............................................................................... 30 Application Information: Boost Converter ................................. 14 Outline Dimensions ....................................................................... 31 ADIsimPower Design Tool ....................................................... 14 Ordering Guide .......................................................................... 31 REVISION HISTORY 2/16 Rev. C to Rev. D 12/06Rev. 0 to Rev. A Changes to Figure 39 and Figure 40 ............................................. 27 Changes to Table 1 ............................................................................. 3 Changes to Table 2 ............................................................................. 5 10/15Rev. B to Rev. C Added Table 3 ....................................................................................5 Moved Figure 3 ................................................................................. 3 Changes to Table 5 .......................................................................... 19 Changes to Shunt Regulation Voltage Parameter, Table 1 .......... 4 Changes to Ordering Guide .......................................................... 31 6/12Rev. A to Rev. B 7/06Revision 0: Initial Version Change to Features Section ............................................................. 1 Added ADIsimPower Design Tool Section ................................. 14 Change to Table 6 ........................................................................... 30 Updated Outline Dimensions ....................................................... 31 Changes to Ordering Guide .......................................................... 31 Rev. D Page 2 of 32