LT®3470A micropower step-down DC/DC converter that integrates 440mA po

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LT®3470A micropower step-down DC/DC converter that integrates 440mA po

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LT3470A Micropower Buck Regulator with Integrated Boost Catch Diodes DESCRIPTION
LT®3470A micropower step-down DC/DC converter that integrates 440mA power switch, catch diode boost diode into profile package. LT3470A combines Burst Mode continuous operation allow tiny inductor capacitors while providing ripple output loads 250mA. With wide input range 40V, LT3470A regulate wide variety power sources, from 2-cell Li-Ion batteries unregulated wall transformers lead-acid batteries. Quiescent current regulation just typical application while zero current shutdown mode disconnects load from input source, simplifying power management battery-powered systems. Fast current limiting hysteretic control protects LT3470A external components against shorted outputs, even input. LT3470A higher output current improved start-up dropout performance compared LT3470.
Lare registered trademarks Linear Technology Corporation. Burst Mode registered trademark Linear Technology Corporation. other trademarks property their respective owners.
Quiescent Current: 12VIN 3.3VOUT Integrated Boost Catch Diodes Input Range: 3.3V 250mA from Input 250mA from 5.7V Input Output Ripple: <10mV Shutdown Mode Output Voltage: 1.25V Hysteretic Mode Control Ripple Burst Mode® Operation Light Loads Continuous Operation Higher Loads Solution Size Small 50mm2 Profile (0.75mm) Thermally Enhanced 8-Lead Package
APPLICATIONS
Automotive Battery Regulation Power Portable Products Distributed Supply Regulation Industrial Supplies Wall Transformer Regulation
TYPICAL APPLICATION
Efficiency Power Loss Load Current
5.7V SHDN BOOST BIAS 22pF 2.2F 200k
3470a TA01
1000
0.22F VOUT 250mA 604k EFFICIENCY LOAD CURRENT (mA) POWER LOSS (mW) LT3470A
3470a TA02
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LT3470A ABSOLUTE MAXIMUM RATINGS
(Note
CONFIGURATION
VIEW BIAS BOOST SHDN
VIN, SHDN Voltage BOOST Voltage BOOST Above Pin. Voltage BIAS Voltage .15V Voltage .VIN Maximum Junction Temperature LT3470AE, LT3470AI 125°C Operating Temperature Range (Note LT3470AE.- 40°C 85°C LT3470AI. -40°C 125°C Storage Temperature Range. -65°C 150°C Lead Temperature (Soldering, sec) 300°C
DDB8 PACKAGE 8-LEAD (3mm 2mm) PLASTIC 80°C/W EXPOSED (PIN GND, MUST SOLDERED
ORDER INFORMATION
LEAD FREE FINISH LT3470AEDDB#PBF LT3470AIDDB#PBF TAPE REEL LT3470AEDDB#TRPBF LT3470AIDDB#TRPBF PART MARKING* LDPR LDPR PACKAGE DESCRIPTION 8-Lead (3mm 2mm) Plastic 8-Lead (3mm 2mm) Plastic TEMPERATURE RANGE -40°C 85°C -40°C 125°C
Consult Marketing parts specified with wider operating temperature ranges. *The temperature grade identified label shipping container. Consult Marketing information non-standard lead based finish parts. more information lead free part marking, http://www.linear.com/leadfree/ more information tape reel specifications,
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LT3470A ELECTRICAL CHARACTERISTICS
PARAMETER Minimum Input Voltage Quiescent Current from VSHDN 0.2V VBIAS Switching VBIAS Switching VSHDN 0.2V VBIAS Switching VBIAS Switching Falling
denotes specifications which apply over full operating temperature range, otherwise specifications 25°C. 10V, VSHDN 10V, VBOOST 15V, VBIAS unless otherwise specified.
CONDITIONS
1.265 0.02
UNITS
Quiescent Current from Bias
Comparator Trip Voltage Bias Current (Note Voltage Line Regulation Minimum Switch Off-Time (Note Maximum Duty Cycle Switch Leakage Current Switch VCESAT Switch VCESAT Without Boost Switch Current Limit Switch Bottom Current Limit Catch Schottky Drop Catch Schottky Reverse Leakage Boost Schottky Drop Boost Schottky Reverse Leakage Minimum Boost Voltage (Note BOOST Current Bias Preload SHDN Current SHDN Input Voltage High SHDN Input Voltage
1.228
1.250 0.0006
100mA VBOOST 100mA IBIAS 50mA 10V, VBIAS
100mA VBOOST VSHDN 2.5V
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 LT3470AE guaranteed meet performance specifications from 85°C. Specifications over -40°C 85°C operating temperature range assured design, characterization correlation
with statistical process controls. LT3470AI specifications guaranteed over -40°C 125°C temperature range. Note Bias current flows pin. Note This minimum voltage across boost capacitor needed guarantee full saturation switch. Note This parameter assured design correlation with statistical process controls.
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LT3470A TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency, VOUT 3.3V
EFFICIENCY TOKO D52LC 25°C 1.255 EFFICIENCY 1.245 1.240 1.250 TOKO D52LC 25°C
25°C unless otherwise noted.
Efficiency, VOUT
1.260
Temperature
LOAD CURRENT (mA)
3470a
LOAD CURRENT (mA)
3470a
TEMPERATURE (°C)
3470a
Bottom Switch Current Limits (VFB Temperature
CURRENT LIMIT (mA) TEMPERATURE (°C) CURRENT
Quiescent Current Temperature
BIAS
BIAS
TEMPERATURE (°C)
3470a
3470a
BIAS Quiescent Current (Bias Temperature
SHDN CURRENT BIAS CURRENT TEMPERATURE (°C)
SHDN Bias Current Temperature
VSHDN
VSHDN 2.5V
TEMPERATURE (°C)
3470a
3470a
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LT3470A TYPICAL PERFORMANCE CHARACTERISTICS
Bias Current (VFB Temperature
CURRENT (nA) CURRENT
25°C unless otherwise noted.
Bias Current (VFB Temperature
TEMPERATURE (°C)
TEMPERATURE (°C)
3470a
3470a
Switch VCESAT (ISW 100mA) Temperature
SWITCH VCESAT (mV) SCHOTTKY TEMPERATURE (°C)
Boost Diode 50mA) Temperature
TEMPERATURE (°C)
3470a
3470a
Catch Diode 100mA) Temperature
SCHOTTKY DIODE LEAKAGE (mA) TEMPERATURE (°C)
Diode Leakage 36V) Temperature
CATCH BOOST
SCHOTTKY
TEMPERATURE (°C)
3470a
3470a
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LT3470A TYPICAL PERFORMANCE CHARACTERISTICS
Switch VCESAT
SWITCH CURRENT (mA)
3470a
25°C unless otherwise noted.
BOOST Current
BOOST CURRENT (mA) SWITCH CURRENT (mA)
3470a
SWITCH VCESAT (mV)
Catch Diode Forward Voltage
SCHOTTKY SCHOTTKY CATCH DIODE CURRENT (mA)
3470a
Boost Diode Forward Voltage
BOOST DIODE CURRENT (mA)
3470a
Minimum Input Voltage, VOUT 3.3V
INPUT VOLTAGE RUN/START LOAD CURRENT (mA)
3470a
Minimum Input Voltage, VOUT
25°C
25°C
INPUT VOLTAGE
RUN/START
LOAD CURRENT (mA)
3470a
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LT3470A FUNCTIONS
SHDN (Pin SHDN used LT3470A shutdown mode. ground shut down LT3470A. Apply more normal operation. shutdown feature used, this pin. (Pin This left floating, connected VIN, tied GND. (Pin supplies current LT3470A's internal regulator internal power switch. This must locally bypassed. (Pin local ground plane below LT3470A circuit components. Return feedback divider this pin. (Pin output internal power switch. Connect this inductor, catch diode boost capacitor. BOOST (Pin BOOST used provide drive voltage, which higher than input voltage, internal bipolar power switch. BIAS (Pin BIAS connects internal boost Schottky diode internal regulator. VOUT when VOUT 2.5V otherwise. When VBIAS BIAS will supply current internal regulator. (Pin LT3470A regulates feedback 1.25V. Connect feedback resistor divider this pin. output voltage according VOUT 1.25V R1/R2) (VOUT /1.25 Exposed (Pin Ground. Must soldered PCB.
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LT3470A BLOCK DIAGRAM
BIAS
500ns SHOT
BOOST
VOUT
BURST MODE DETECT
SHDN
VREF 1.25V
3470a
ENABLE
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LT3470A OPERATION
LT3470A uses hysteretic control scheme conjunction with Burst Mode operation provide output ripple quiescent current while using tiny inductor capacitors. Operation best understood studying Block Diagram. error amplifier measures output voltage through external resistor divider tied pin. voltage higher than VREF, error amplifier will shut high power circuitry, leaving LT3470A micropower state. voltage falls, error amplifier will enable power section, causing chip begin switching, thus delivering charge output capacitor. load light part will alternate between micropower switching states keep output regulation (See Figure 1a). higher loads part will switch continuously while error servos bottom current limits regulate voltage 1.25V (See Figure 1b). switching action controlled latch current comparators follows: switch turns current through ramps until current
LOAD VOUT 20mV/DIV VOUT 20mV/DIV 100mA/DIV 100mA/DIV 1ms/DIV 10mA LOAD VOUT 20mV/DIV VOUT 20mV/DIV 150mA LOAD 1s/DIV
comparator trips resets latch causing switch turn off. While switch off, inductor current ramps down through catch diode. When both bottom current comparator trips minimum off-time one-shot expires, latch turns switch back thus completing full cycle. hysteretic action this control scheme results switching frequency that depends inductor value, input output voltage. Since switch only turns when catch diode current falls below threshold, part will automatically switch slower keep inductor current under control during start-up short-circuit conditions. switch driver operates from either input from BOOST pin. external capacitor internal diode used generate voltage BOOST that higher than input supply. This allows driver fully saturate internal bipolar power switch efficient operation. SHDN grounded, internal circuits turned current reduces device leakage current, typically 100nA.
200mA LOAD
100mA/DIV 5s/DIV
3470a F01a
100mA/DIV 1s/DIV
3470a
(1a) Burst Mode Operation
(1b) Continuous Operation
Figure Operating Waveforms LT3470A Converting Using Inductor Output Capacitor
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LT3470A APPLICATIONS INFORMATION
Input Voltage Range minimum input voltage required generate particular output voltage LT3470A application limited either undervoltage lockout maximum duty cycle. duty cycle fraction time that internal switch determined input output voltages: VOUT where forward voltage drop catch diode (~0.6V) voltage drop internal switch maximum load (~0.4V). Given DCMAX 0.90, this leads minimum input voltage VIN(MIN) VOUT DCMAX where VIN(MAX) maximum input voltage application, tON-TIME(MIN) ~150ns IMAX maximum allowable increase switch current during minimum switch on-time (150mA). While this equation provides safe inductor value, resulting application circuit switch high frequency yield good efficiency. advised that switching frequency below 1.2MHz during normal operation:
DC)( VOUT
where switching frequency, ripple current inductor (~200mA), forward voltage drop catch diode, VOUT desired output voltage. application circuit intended operate high duty cycles (VIN close VOUT), important look calculated value switch off-time: tOFF-TIME calculated tOFF-TIME should more than LT3470A's minimum tOFF-TIME (See Electrical Characteristics), application circuit capable delivering full rated output current. full output current 250mA required, calculated tOFF-TIME made less than minimum tOFF-TIME possibly allowing smaller inductor. Table inductor value selection guide.
Table Recommended Inductors Loads 250mA
VOUT 2.5V 3.3V
This analysis assumes part started such that capacitor tied between BOOST pins charged more than proper start-up, minimum input voltage limited boost circuit detailed section BOOST Considerations. maximum input voltage limited absolute maximum rating 40V, provided inductor sufficient value used. Inductor Selection switching action LT3470A during continuous operation produces square wave that results triangle wave current inductor. hysteretic mode control regulates bottom current limits (see Electrical Characteristics) such that average inductor current equals load current. safe operation, must noted that LT3470A cannot turn switch less than ~150ns. inductor small input voltage high, current through switch exceed safe operating limit before LT3470A able turn off. prevent this from happening, following equation provides minimum inductor value: LMIN VIN(MAX) tON-TIME(MIN) IMAX
Choose inductor that intended power applications. Table lists several manufacturers inductor series. robust output short-circuit protection high 40V) least inductor with minimum 450mA saturation current. short-circuit performance required, inductors with ISAT 300mA more
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LT3470A APPLICATIONS INFORMATION
Table Inductor Vendors
VENDOR Coilcraft www.coilcraft.com PART SERIES DO1605 ME3220 DO3314 CR32 CDRH3D16/HP CDRH3D28 CDRH2D18/HP DB320C D52LC WE-PD2 WE-TPC SD10 LQH43C LQH32C INDUCTANCE RANGE SIZE (mm)
Sumida
www.sumida.com
Toko Elektronik Coiltronics Murata
www.tokoam.com www.we-online.com www.cooperet.com www.murata.com
used. important note that inductor saturation current reduced high temperatures-see inductor vendors more information. Input Capacitor Step-down regulators draw current from input supply pulses with very fast rise fall times. input capacitor required reduce resulting voltage ripple LT3470A force this switching current into tight local loop, minimizing EMI. input capacitor must have impedance switching frequency this effectively. 2.2F ceramic capacitor satisfies these requirements. input source impedance high, larger value capacitor required keep input ripple low. this case, electrolytic more parallel with ceramic good combination. aware that input capacitor subject large surge currents LT3470A circuit connected impedance supply, that some electrolytic capacitors particular tantalum) must specified such use. Output Capacitor Output Ripple output capacitor filters inductor's ripple current stores energy satisfy load current when LT3470A quiescent. order keep output voltage ripple low, impedance capacitor must
LT3470A's switching frequency. capacitor's equivalent series resistance (ESR) determines this impedance. Choose with intended switching regulators. contribution ripple voltage approximately ILIM ESR. should less than ~150m. value output capacitor must large enough accept energy stored inductor without large change output voltage. Setting this voltage step equal output voltage, output capacitor must COUT VOUT
Where ILIM current limit with (see Electrical Characteristics). example, LT3470A producing 3.3V with requires calculated value relaxed small circuit size more important than output ripple. Sanyo's POSCAP series B-case provides very good performance small package LT3470A. Similar performance traditional tantalum capacitors requires larger package (C-case). With high quality capacitor filtering ripple current from inductor, output voltage ripple determined delay LT3470A's feedback comparator. This ripple reduced further adding small (typically 22pF) phase lead capacitor between output feedback pin.
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LT3470A APPLICATIONS INFORMATION
Ceramic Capacitors Ceramic capacitors small, robust have very ESR. However, ceramic capacitors cause problems when used with LT3470A. ceramic capacitors suitable. types stable over temperature applied voltage give dependable service. Other types, including have very large temperature voltage coefficients capacitance. application circuit they have only small fraction their nominal capacitance resulting much higher output voltage ripple than expected. Ceramic capacitors piezoelectric. LT3470A's switching frequency depends load current, light loads LT3470A excite ceramic capacitor audio frequencies, generating audible noise. Since LT3470A operates lower current limit during Burst Mode operation, noise typically very quiet casual ear. this audible noise unacceptable, high performance electrolytic capacitor output. input capacitor parallel combination 2.2F ceramic capacitor cost electrolytic capacitor. final precaution regarding ceramic capacitors concerns maximum input voltage rating LT3470A. ceramic input capacitor combined with trace cable inductance forms high quality (under damped) tank circuit. LT3470A circuit plugged into live supply, input voltage ring twice nominal value, possibly exceeding LT3470A's rating. This situation easily avoided; Hot-Plugging Safely section.
Table Capacitor Vendors
Vendor Panasonic Phone (714) 373-7366 www.panasonic.com Part Series Ceramic, Polymer, Tantalum Ceramic, Tantalum Ceramic, Polymer, Tantalum Ceramic Ceramic, Tantalum Ceramic
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BOOST BIAS Considerations Capacitor internal boost Schottky diode (see Block Diagram) used generate boost voltage that higher than input voltage. most cases 0.22F capacitor will work well. Figure shows ways arrange boost circuit. BOOST must more than 2.5V above best efficiency. outputs 3.3V above, standard circuit (Figure best. outputs between 2.5V 0.47F lower output voltages boost diode tied input
BOOST BIAS 0.22F
LT3470A VOUT
VBOOST VOUT VBOOST VOUT
(2a)
BIAS
3470a
BOOST
0.22F
LT3470A VOUT
VBOOST VBOOST
(2b)
Figure Circuits Generating Boost Voltage
Comments Series
Kemet Sanyo
(864) 963-6300 (408) 749-9714
www.kemet.com www.sanyovideo.com
T494, T495 POSCAP
Murata Taiyo Yuden
(404) 436-1300
www.murata.com www.avxcorp.com
Series
(864) 963-6300
www.taiyo-yuden.com
LT3470A APPLICATIONS INFORMATION
(Figure 2b). circuit Figure more efficient because BOOST current BIAS quiescent current comes from lower voltage source. must also sure that maximum voltage ratings BOOST BIAS pins exceeded. LT3470A monitors boost capacitor sufficient voltage such that switch allowed fully saturate. When boost voltage falls below adequate levels (1.8V typical) switch will operate with about drop, internal current source will begin pull 50mA (typical) from BIAS which typically connected output. This current forces LT3470A switch more often with more inductor current, which recharges
Minimum Input Voltage, VOUT 3.3V
INPUT VOLTAGE LOAD CURRENT (mA)
3470a F03a
boost capacitor. When boost capacitor voltage above 1.8V (typical) current source turns off, part enter BurstMode. This cycle will repeat anytime there undervoltage condition boost capacitor. Figure minimum input voltage outputs 3.3V Shorted Input Protection inductor chosen that won't saturate excessively switch current limit maximum 525mA, LT3470A buck regulator will tolerate shorted output even 40V. There another situation consider systems where output will held high when input LT3470A absent. This occur battery charging applications battery backup systems where battery some other supply diode OR-ed with LT3470A's output. allowed float SHDN held high (either logic signal because tied VIN), then LT3470A's internal circuitry will pull quiescent current through pin. This fine your system tolerate this state. ground SHDN pin, current will drop essentially zero. However, grounded while output held high, then parasitic diodes inside LT3470A pull large currents from output through pin. Figure shows circuit that will only when input voltage present that protects against shorted reversed input.
BOOST BIAS VOUT
25°C
RUN/START
Minimum Input Voltage, VOUT
25°C
INPUT VOLTAGE
100k
LT3470A SHDN
RUN/START
BACKUP
3470a
LOAD CURRENT (mA)
3470a F03b
Figure Minimum Input Voltage Depends Output Voltage, Load Current Boost Circuit
Figure Diode Prevents Shorted Input from Discharging Backup Battery Tied Output; Also Protects Circuit from Reversed Input. LT3470A Runs Only When Input Present Hot-Plugging Safely
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LT3470A APPLICATIONS INFORMATION
Layout proper operation minimum EMI, care must taken during printed circuit board layout. Note that large, switched currents flow power switch, internal catch diode input capacitor. loop formed these components should small possible. Furthermore, system ground should tied regulator ground only place; this prevents switched current from injecting noise into system ground. These components, along with inductor output capacitor, should placed same side circuit board, their connections should made that layer. Place local, unbroken ground plane below these components, this ground plane system ground location, ideally ground terminal output capacitor Additionally, BOOST nodes should kept small possible. Unshielded inductors induce noise feedback path resulting instability increased output ripple. avoid this problem, vias route VOUT trace under ground plane feedback divider shown Figure Finally, keep node small possible that ground ground traces will shield from BOOST nodes. Figure shows component placement with trace, ground plane locations. Include vias near pin, pad, LT3470A help remove heat from LT3470A ground plane.
SHDN
VOUT
3470a
Figure Good Layout Ensures Proper, Operation
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LT3470A APPLICATIONS INFORMATION
Hot-Plugging Safely small size, robustness impedance ceramic capacitors make them attractive option input bypass capacitor LT3470A. However, these capacitors cause problems LT3470A plugged into live supply (see Linear Technology Application Note complete discussion). loss ceramic capacitor combined with stray inductance series with power source forms under damped tank circuit, voltage LT3470A ring twice nominal input voltage, possibly exceeding LT3470A's rating damaging part. input supply poorly controlled user will plugging LT3470A into energized supply, input network should designed prevent this overshoot. Figure shows waveforms that result when LT3470A circuit connected supply through feet 24-gauge twisted pair. first plot response with 2.2F ceramic capacitor input. input voltage rings high input current peaks 20A. method damping tank circuit another capacitor with series resistor circuit. Figure aluminum electrolytic capacitor been added. This capacitor's high equivalent series resistance damps circuit eliminates voltage overshoot. extra capacitor improves frequency ripple filtering slightly improve efficiency circuit, though likely largest component circuit. alternative solution shown Figure resistor added series with input eliminate voltage overshoot also reduces peak input current). 0.1F capacitor improves high frequency filtering. This solution smaller less expensive than electrolytic capacitor. high input voltages impact efficiency minor, reducing efficiency less than half percent output full load operating from 24V. High Temperature Considerations junction temperature LT3470A must lower than maximum rating 125°C. This generally concern unless ambient temperature above 85°C. higher temperatures, care should taken layout circuit ensure good heat sinking LT3470A. maximum load current should derated ambient temperature approaches maximum junction rating. temperature calculated multiplying LT3470A power dissipation thermal resistance from junction ambient. Power dissipation within LT3470A estimated calculating total power loss from efficiency measurement. Thermal resistance depends layout circuit board choice package. package with exposed thermal resistance approximately 80°C/W. Finally, aware that high ambient temperatures internal Schottky diode will have significant leakage current (see Typical Performance Characteristics) increasing quiescent current LT3470A converter.
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LT3470A APPLICATIONS INFORMATION
CLOSING SWITCH SIMULATES PLUG LT3470A 10V/DIV
2.2F
IMPEDANCE ENERGIZED SUPPLY
STRAY INDUCTANCE FEET METERS) TWISTED PAIR
10A/DIV 10s/DIV
(6a)
LT3470A AI.EI.
2.2F
10V/DIV
10A/DIV 10s/DIV
(6b)
LT3470A 0.1F 2.2F 10A/DIV 10s/DIV
3470a
10V/DIV
(6c) Figure Well Chosen Input Network Prevents Input Voltage Overshoot Ensures Reliable Operation When LT3470A Connected Live Supply
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LT3470A APPLICATIONS INFORMATION
3.3V Step-Down Converter
SHDN BOOST BIAS 22pF 200k
3470a TA03
LT3470A
0.22F 6.3V
VOUT 3.3V 250mA 324k
C3216JB1H105M JMK316 BJ226ML-T TOKO A993AS-270M=P3
Step-Down Converter
5.7V SHDN BOOST BIAS 22pF 200k
3470a TA04
LT3470A
0.22F 6.3V
VOUT 250mA 604k
C3216JB1H105M JMK316 BJ226ML-T TOKO A914BYW-330M=P3
2.5V Step-Down Converter
SHDN BOOST BIAS 22pF 200k
3470a TA07
LT3470A
0.47F 6.3V
VOUT 2.5V 250mA 200k
C3216JB1H105M C2012JB0J226M SUMIDA CDRH3D28
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LT3470A TYPICAL APPLICATIONS
1.8V Step-Down Converter
SHDN BIAS 332k
3470a TA05
BOOST
LT3470A
0.22F
VOUT 1.8V 250mA 147k
22pF
C3216JB1H105M C2012JB0J226M MURATA LQH32CN150K53
Step-Down Converter
SHDN BOOST BIAS 22pF 100k
3470a TA06
LT3470A
0.22F
VOUT 250mA 866k
C3216JB1H105M C3216JB1C106M MURATA LQH32CN150K53
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LT3470A PACKAGE DESCRIPTION
Package 8-Lead Plastic (3mm 2mm)
(Reference 05-08-1702
0.61 ±0.05 SIDES) 0.70 ±0.05 2.55 ±0.05 1.15 ±0.05 PACKAGE OUTLINE 0.25 0.05 0.50 2.20 ±0.05 SIDES) MARK (SEE NOTE 0.200
3.00 ±0.10 SIDES)
0.05 2.00 ±0.10 SIDES) 0.56 0.05 SIDES) 0.75 ±0.05
0.115
0.40 0.10
0.25 0.05 2.15 ±0.05 SIDES)
0.50
0.20 0.25 CHAMFER
(DDB8) 0905
RECOMMENDED SOLDER PITCH DIMENSIONS NOTE: DRAWING CONFORMS VERSION (WECD-1) JEDEC PACKAGE OUTLINE M0-229 DRAWING SCALE DIMENSIONS MILLIMETERS DIMENSIONS EXPOSED BOTTOM PACKAGE INCLUDE MOLD FLASH. MOLD FLASH, PRESENT, SHALL EXCEED 0.15mm SIDE EXPOSED SHALL SOLDER PLATED SHADED AREA ONLY REFERENCE LOCATION BOTTOM PACKAGE
0.05
BOTTOM VIEW-EXPOSED
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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.
LT3470A RELATED PARTS
PART NUMBER LT1616 LT1676 LT1765 LT1766 LT1767 LT1776 LTC®1877 LTC1879 LT1933 LT1934 LT1956 LTC3405/LTC3405A LTC3406/LTC3406B LTC3411 LTC3412 LT3430 LT3470 DESCRIPTION 25V, 500mA (IOUT), 1.4MHz, High Efficiency Step-Down DC/DC Converter 60V, 440mA (IOUT), 100kHz, High Efficiency Step-Down DC/DC Converter 25V, 2.75A (IOUT), 1.25MHz, High Efficiency Step-Down DC/DC Converter 60V, 1.2A (IOUT), 200kHz, High Efficiency Step-Down DC/DC Converter 25V, 1.2A (IOUT), 1.25MHz, High Efficiency Step-Down DC/DC Converter 40V, 550mA (IOUT), 200kHz, High Efficiency Step-Down DC/DC Converter 600mA (IOUT), 550kHz, Synchronous Step-Down DC/DC Converter 1.2A (IOUT), 550kHz, Synchronous Step-Down DC/DC Converter 36V, 600mA, 500kHz, High Efficiency Step-Down DC/DC Converter 34V, 250mA (IOUT), Micropower, Step-Down DC/DC Converter 60V, 1.2A (IOUT), 500kHz, High Efficiency Step-Down DC/DC Converter 300mA (IOUT), 1.5MHz, Synchronous Step-Down DC/DC Converter 600mA (IOUT), 1.5MHz, Synchronous Step-Down DC/DC Converter 1.25A (IOUT), 4MHz, Synchronous Step-Down DC/DC Converter 2.5A (IOUT), 4MHz, Synchronous Step-Down DC/DC Converter 60V, 2.75A (IOUT), 200kHz, High Efficiency Step-Down DC/DC Converter 40V, 200mA, Micropower Step-Down DC/DC Converter COMMENTS 3.6V 25V, VOUT 1.25V, 1.9mA, <1A, ThinSOT Package 7.4V 60V, VOUT 1.24V, 3.2mA, 2.5A, Package 25V, VOUT 1.2V, 1mA, 15A, TSSOP16E Packages 5.5V 60V, VOUT 1.2V, 2.5mA, 25A, TSSOP16/E Package 25V; VOUT 1.2V, 1mA, MS8/E Packages 7.4V 40V; VOUT 1.24V, 3.2mA, 30A, Packages 2.7V 10V; VOUT 0.8V, 10A, <1A, Package 2.7V 10V; VOUT 0.8V, 15A, <1A, TSSOP16 Package 3.6V 36V; VOUT 1.25V, 2.5A, <1A, ThinSOT DFN-6 Package 3.2V 34V; VOUT 1.25V, 12A, <1A, ThinSOT DFN-6 Package 5.5V 60V, VOUT 1.2V, 2.5mA, 25A, TSSOP16/E Package 2.7V VOUT 0.8V, 20A, <1A, ThinSOT Package 2.5V 5.5V, VOUT 0.6V, 20A, <1A, ThinSOT Package 2.5V 5.5V, VOUT 0.8V, 60A, <1A, Package 2.5V 5.5V, VOUT 0.8V, 60A, <1A, TSSOP16E Package 5.5V 60V, VOUT 1.2V, 2.5mA, 30A, TSSOP16E Package 40V, VOUT 1.25V, 35A, <1A, DFN-8, ThinSOT Packages
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Linear Technology Corporation
(408) 432-1900 FAX: (408) 434-0507
1108 PRINTED
1630 McCarthy Blvd., Milpitas, 95035-7417
www.linear.com
LINEAR TECHNOLOGY CORPORATION 2008

LT®3470A micropower step-down DC/DC converter that integrates 440mA po

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