LT3489 2MHz Boost DC/DC Converter with 2.5A Switch Soft-Start DESCRIPT
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LT3489 2MHz Boost DC/DC Converter with 2.5A Switch Soft-Start DESCRIPTIO
LT®3489 fixed frequency step-up DC/DC converter containing internal 2.5A, switch. LT3489 ideal large TFT-LCD panel power supplies. LT3489 switches 2MHz, allowing tiny, profile inductors value ceramic capacitors. Loop compensation either internal external, giving user flexibility setting loop compensation allowing optimized transient response with ceramic output capacitors. Soft-start controlled with external capacitor, which determines input current ramp rate during start-up. 8-lead MS8E package high switching frequency ensure profile overall solution less than 1.1mm high.
Lare registered trademarks Linear Technology Corporation. other trademarks property their respective owners.
2.5A, 0.12, Internal Switch 2MHz Switching Frequency Integrated Soft-Start Function Range: 2.6V Adjustable Output from VCESAT Switch: 110mV (Typical) 610mA from 3.3V Input Internal External Loop Compensation Small 8-Lead MS8E
APPLICATIO
TFT-LCD Bias Supplies Receivers Modems Local Power Supply
TYPICAL APPLICATIO
Profile, Triple Output Supply (8V, -8V, 23V)
10mA 0.1µF 0.1µF 0.1µF EFFICIENCY
3.3V SHDN 4.7µF 100nF
2.2µH
AVDD 610mA 28.7k
LT3489 5.23k 37.4k 220pF 0.1µF 20µF
COMP
3489 TA01
VOFF 20mA
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Efficiency
LOAD 10mA VOFF LOAD 20mA AVDD LOAD CURRENT (mA)
3489 TA01b
LT3489 ABSOLUTE
(Note
RATI
PACKAGE/ORDER ATIO
VIEW SHDN COMP
Voltage .16V Voltage -0.4V COMP, Voltages SHDN Voltage .16V Current Into .±1mA Maximum Junction Temperature 125°C Operating Temperature Range (Note -40°C 85°C Storage Temperature Range. -65°C 150°C Lead Temperature (Soldering, sec) 300°C
MS8E PACKAGE 8-LEAD PLASTIC MSOP TJMAX 125°C, 40°C/W, 10°C/W EXPOSED (PIN (MUST SOLDERED PCB)
ORDER PART NUMBER LT3489EMS8E
MS8E PART MARKING LTBYF
Order Options Tape Reel: Lead Free: #PBF Lead Free Tape Reel: #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult Marketing parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
PARAMETER Minimum Operating Voltage Maximum Operating Voltage Feedback Voltage CONDITIONS
denotes specifications which apply over full operating temperature range, otherwise specifications 25°C. VSHDN unless otherwise noted. (Note
1.22 1.21 1.235 VSHDN 2.5V, Switching VSHDN 2.6V
1.26 1.26
UNITS mhos
Bias Current Error Transconductance Error Voltage Gain Quiescent Current Quiescent Current Shutdown Reference Line Regulation Switching Frequency Maximum Switch Duty Cycle Switch Current Limit Switch VCESAT Switch Leakage Current SHDN Current
1.25V (Note
0.01 0.23 0.01
0.05
(Note VSHDN VSHDN 1.4V VSHDN 0.5V
SHDN Threshold Soft-Start Charging Current
Note Stresses beyond those listed under Absolute Maximum Ratings cause permanent damage device. Exposure Absolute Maximum Rating condition extended periods affect device reliability lifetime. Note LT3489E guaranteed meet performance specifications from 70°C. Specifications over 40°C 85°C operating
temperature range assured design, characterization correlation with statistical process controls. Note Current flows pin. Note Current limit guaranteed design and/or correlation static test. Current limit independent duty cycle guaranteed design.
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LT3489 TYPICAL PERFOR CHARACTERISTICS
Feedback Voltage
1.27 1.26 FEEDBACK VOLTAGE 1.25 1.24 1.23 1.22 1.21 OSCILLATOR FREQUENCY (MHz)
CURRENT LIMIT
TEMPERATURE (°C)
Switch VCE(SAT) Voltage
QUIESCENT CURRENT (mA) SWITCH CURRENT -50°C 25°C 125°C
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VCE(SAT) (mV)
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25°C unless otherwise noted.
Oscillator Frequency
TEMPERATURE (°C)
Current Limit
TEMPERATURE (°C)
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Quiescent Current
1A/DIV VOUT 100mV/DIV COUPLED 10V/DIV
Switching Waveform Cover Page Circuit
TEMPERATURE (°C)
3.3V 200ns/DIV AVDD ILOAD, AVDD 400mA 23V, 10mA VOFF -8V, 20mA
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LT3489 CTIO
(Pin Error Amplifier Output Pin. external compensation network this pin, internal compensation network shorting COMP pin. (Pin Feedback Pin. Reference voltage 1.235V. Connect resistive divider here. Minimize trace area VOUT according VOUT 1.235 R1/R2). SHDN (Pin Shutdown Pin. more enable device. Ground shut down. float this pin. (Pin Ground. directly local ground plane. (Pin Switch Pin. This collector internal power switch. Minimize metal trace area connected this minimize EMI. (Pin Input Supply Pin. Must locally bypassed. COMP (Pin Internal Compensation Pin. Provides internal compensation network. directly internal compensation. use. (Pin Soft-Start Pin. Place soft-start capacitor here. Upon start-up, current charges capacitor 1.8V. larger capacitor slower start-up. Leave floating use. Exposed (Pin Ground. Must soldered PCB.
BLOCK DIAGRA
VOUT (EXTERNAL) (EXTERNAL) 1.235V REFERENCE
RAMP GENERATOR
2MHz OSCILLATOR
SHUTDOWN
SHDN
Figure Block Diagram
COMP 100k 125pF COMPARATOR DRIVER
0.01
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LT3489 OPERATIO
LT3489 uses constant frequency, current mode control scheme provide excellent line load regulation. Please refer Figure following description part's operation. start oscillator cycle, latch set, turning power switch, switch current flows through internal current sense resistor generating voltage. This voltage added stabilizing ramp resulting into positive terminal comparator, When this voltage exceeds level negative input latch reset, turning power switch. level negative input pin) error amplifier (gm) simply amplified version difference between feedback voltage reference voltage 1.235V. this manner, error amplifier sets correct peak current level keep output regulation.
soft-start function provided enable clean start-up LT3489. When part brought shutdown, 10µA current sourced pin. connecting external capacitor pin, rate voltage rise set. Typical values soft-start capacitor range from 10nF 200nF. indirectly limits rate rise pin, which turn limits peak switch current. Current limit shown Figure switch current constantly monitored allowed exceed nominal value 2.5A. switch current reaches 2.5A, latch reset regardless output comparator This current limit helps protect power switch well external components connected LT3489.
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LT3489 APPLICATIO ATIO
Inductor Selection Several inductors that work well with LT3489 listed Table This table exclusive; there many other manufacturers inductors that used. Consult each manufacturer more detailed information their entire selection related parts, many different sizes shapes available. Ferrite core inductors should used obtain best efficiency, core losses 2MHz much lower ferrite cores than cheaper powdered-iron ones. Choose inductor that handle least 2.5A without saturating, ensure that inductor (copper wire resistance) minimize power losses. 2.2H inductor will best choice most LT3489 designs. Note that some applications, current handling requirements inductor lower, such SEPIC topology where each inductor only carries one-half total switch current. inductors shown Table were chosen small size. better efficiency, similar valued inductors with larger volume.
Table Recommended Inductors
PART SD25-2R2 SD25-3R3 SD25-4R7 A916CY-2R7M A916CY-3R3M A916CY-4R7M LQH55DN2R2M03 LQH55DN3R3M03 LQH55DN4R7M03 TYPICAL 18.3 21.4 26.3 SIZE (mm) 5.45 5.45 VENDOR CooperBussmann (888) 414-2645 www.cooperet.com Toko www.toko.com Murata (770) 436-1300 www.murata.com
Table Ceramic Capacitor Manufacturers
Taiyo Yuden Murata (408) 573-4150 www.t-yuden.com (843) 448-9411 www.avxcorp.com (770) 436-1300 www.murata.com
Capacitor Selection (equivalent series resistance) capacitors should used output minimize output ripple voltage. Multilayer ceramic capacitors excellent choice, they have extremely available very small packages. dielectrics preferred, these materials retain capacitance over wide voltage temperature ranges. 4.7µF 20µF output capacitor sufficient most applications, systems with very output currents need only 2.2µF output capacitor. Solid tantalum OS-CON capacitors used, they will occupy more board area than ceramic will have higher ESR. Always capacitor with sufficient voltage rating. Ceramic capacitors also make good choice input decoupling capacitor, which should placed close possible LT3489. 2.2F 4.7F input capacitor sufficient most applications. Table shows list several ceramic capacitor manufacturers. Consult manufacturers detailed information their entire selection ceramic parts.
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LT3489 APPLICATIO ATIO
Diode Selection Schottky diodes, with their forward voltage drop fast switching speed, ideal LT3489 applications. Table lists several Schottky diodes that work well with LT3489. diode's average current rating must exceed average output current. diode's maximum reverse voltage must exceed output voltage. diode conducts current only when power switch turned (typically less than duty cycle), diode sufficient most designs. companies below also offer Schottky diodes with high voltage current ratings.
Table Suggested Diodes
MANUFACTURER MAXIMUM PART NUMBER CURRENT UPS340 UPS315 B220 B230 B240 B320 B330 B340 SBM340 MAXIMUM REVERSE VOLTAGE
MANUFACTURER Microsemi www.microsemi.com Diodes, www.diodes.com
Frequency Compensation compensate feedback loop LT3489, series resistor-capacitor network should connected from COMP GND. most applications, capacitor range 220pF 680pF will suffice. good starting value compensation capacitor, 470pF. compensation resistor, usually range 100k. thorough analysis switching regulator control loop within scope this data sheet will presented here, values 680pF will good choice many designs.
Setting Output Voltage output voltage, select values (see Figure according following equation: 1.235V good range from 30k. Board Layout high speed operation LT3489 demands careful attention board layout. high-current switching regulators like LT3489, board layout must have good thermal performance. Vias located underneath part should connected internal ground plane improve heat transfer from LT3489 board. will advertised performance with careless layout. Thermal noise consideration must taken into account. Figure shows recommended component placement boost converter.
GROUND PLANE SHUTDOWN LT3489 MULTIPLE VIAs VOUT
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Figure Recommended Component Placement Boost Converter. Note Direct High Current Paths Using Wide Traces. Minimize Trace Area (VC) (FB). Multiple Vias Copper Ground Plane. Vias Location Only Avoid Introducing Switching Currents Into Ground Plane
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LT3489 TYPICAL APPLICATIO
Output Boost Converter
3.3V 2.2µH SHDN LT3489 5.23k VOUT 650mA, 3.3V 1.1A, 28.7k 20µF
4.7µF 100nF
08056D475KAT 10µF, TAIYO YUDEN LMK3168BJ106ML DIODES INC. DFLS220L COOPER BUSSMANN SD25-2R2 *EXPOSED MUST ALSO GROUNDED
Efficiency
EFFICIENCY 3.3V LOAD CURRENT
3489 TA09
COMP 35.7k 330pF
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Transient Response
VOUT 100mV/DIV COUPLED 1A/DIV 400mA IOUT 200mA 3.3V 50µs/DIV
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LT3489 TYPICAL APPLICATIO
Output Boost Converter
3.3V 3.3µH SHDN LT3489 100nF COMP 9.76k VOUT 625mA, 410mA, 3.3V 84.5k 10µF
Efficiency
EFFICIENCY LOAD CURRENT 3.3V 300mA IOUT 100mA 1A/DIV VOUT 500mV/DIV COUPLED
4.7µF 16.5k 680pF
Taiyo Yuden JMK212BJ475MG, 4.7µF, 6.3V Taiyo Yuden GMK316BJ106ML, 10µF, Diodes, Inc. DFLS220 Toko A916CY-3R3M (Type D63CB)
3489 TA03
Transient Response
3.3V
50µs/DIV
3489 TA06
3489 TA05
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LT3489 TYPICAL APPLICATIO
10mA 0.1µF 2.2µH SHDN LT3489 GND* 5.23k 0.1µF 0.1µF 10mA 28.7k 20µF AVDD 610mA 4.7µF 100nF COMP 37.4k 220pF 08056D475KAT 10µF, TAIYO YUDEN LMK316BJ106ML 10µF, 1µF, AVX08053D105KAT 0.1µF, 0.1µF, DIODES INC. DFLS220L ZETEX BAT54S EQUIVALENT COOPER BUSSMANN SD25-2R2 EXPOSED MUST ALSO GROUNDED 0.1µF VOFF 20mA
3489 TA04
3.3V
Effciency
EFFICIENCY LOAD 10mA VOFF LOAD 20mA AVDD LOAD CURRENT (mA) 400mA ILOAD 200mA 1A/DIV AVDD 100mV/DIV COUPLED
Transient Response
AVDD 5V/DIV 20V/DIV VOFF 5V/DIV
Start-Up Waveforms
0.5A/DIV 5µs/DIV
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5ms/DIV
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LT3489 PACKAGE DESCRIPTIO
MS8E Package 8-Lead Plastic MSOP
(Reference 05-08-1662)
BOTTOM VIEW EXPOSED OPTION 2.06 0.102 (.081 .004) 1.83 0.102 (.072 .004)
2.794 0.102 (.110 .004)
0.889 0.127 (.035 .005)
5.23 (.206)
2.083 0.102 3.20 3.45 (.082 .004) (.126 .136) 3.00 0.102 (.118 .004) (NOTE
0.42 0.038 (.0165 .0015)
0.65 (.0256)
0.52 (.0205)
RECOMMENDED SOLDER LAYOUT
DETAIL 4.90 0.152 (.193 .006) 3.00 0.102 (.118 .004) (NOTE
0.254 (.010) GAUGE PLANE
0.53 0.152 (.021 .006) DETAIL 0.18 (.007) SEATING PLANE 0.22 0.38 (.009 .015) 1.10 (.043)
0.86 (.034)
NOTE: DIMENSIONS MILLIMETER/(INCH) DRAWING SCALE DIMENSION DOES INCLUDE MOLD FLASH, PROTRUSIONS GATE BURRS. MOLD FLASH, PROTRUSIONS GATE BURRS SHALL EXCEED 0.152mm (.006") SIDE DIMENSION DOES INCLUDE INTERLEAD FLASH PROTRUSIONS. INTERLEAD FLASH PROTRUSIONS SHALL EXCEED 0.152mm (.006") SIDE LEAD COPLANARITY (BOTTOM LEADS AFTER FORMING) SHALL 0.102mm (.004")
0.65 (.0256)
0.127 0.076 (.005 .003)
MSOP (MS8E) 0603
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Information furnished Linear Technology Corporation believed accurate reliable. However, responsibility assumed use. Linear Technology Corporation makes representation that interconnection circuits described herein will infringe existing patent rights.
LT3489 RELATED PARTS
PART NUMBER LT1613 LT1615/LT1615-1 LT1618 LT1930/LT1930A LT1935 LT1946/LT1946A LT1961 LT3436 LT3464 LT3467/LT3467A LT3477 LT3479 DESCRIPTION 550mA (ISW), 1.4MHz, High Efficiency Step-Up DC/DC Converter 300mA/80mA (ISW), High Efficiency Step-Up DC/DC Converters 1.5A (ISW), 1.25MHz, High Efficiency Step-Up DC/DC Converter (ISW), 1.2MHz/2.2MHz, High Efficiency Step-Up DC/DC Converters (ISW), 1.2MHz/2.7MHz, High Efficiency Step-Up DC/DC Converter 1.5A (ISW), 1.2MHz, High Efficiency Step-Up DC/DC Converters 1.5A (ISW), 1.25MHz, High Efficiency Step-Up DC/DC Converter (ISW), 1MHz, Step-Up DC/DC Converter COMMENTS VIN: 0.9V 10V, VOUT(MAX) 34V, 3mA, <1A, ThinSOT Package VIN: 15V, VOUT(MAX) 34V, 20A, <1A, ThinSOT Package VIN: 1.6V 18V, VOUT(MAX) 35V, 1.8mA, <1A, Package VIN: 2.6V 16V, VOUT(MAX) 34V, 4.2mA/5.5mA, <1A, ThinSOT Package VIN: 2.3V 16V, VOUT(MAX) 38V, 3mA, <1A, ThinSOT Package VIN: 2.45V 16V, VOUT(MAX) 34V, 3.2mA, <1A, Package VIN: 25V, VOUT(MAX) 35V, 0.9mA, MS8E Package VIN: 25V, VOUT(MAX) 34V, 0.9mA, <6A, TSSOP-16E Package
85mA (ISW), High Efficiency Step-Up DC/DC Converter VIN: 2.3V 10V, VOUT(MAX) 34V, 25A, <1A, with Integrated Schottky Disconnect ThinSOT Package 1.1A (ISW), 1.3MHz/2.7MHz, High Efficiency Step-Up DC/DC Converters (ISW), 3.5MHz, High Efficiency Step-Up DC/DC Converter with Dual Rail-to-Rail Current Sense (ISW), 3.5MHz, High Efficiency Step-Up DC/DC Converter VIN: 2.6V 16V, VOUT(MAX) 40V, 1.2mA, <1A, ThinSOT Package VIN: 2.5V 24V, VOUT(MAX) 40V, 5mA, <1A, QFN, TSSOP-20E Packages VIN: 2.5V 24V, VOUT(MAX) 40V, 5mA, <1A, DFN. TSSOP-16E Packages
ThinSOT trademark Linear Technology Corporation.
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Linear Technology Corporation
(408) 432-1900 FAX: (408) 434-0507
0606 PRINTED
1630 McCarthy Blvd., Milpitas, 95035-7417
www.linear.com
LINEAR TECHNOLOGY CORPORATION 2006
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