LTC3400-1 600mA, 1.2MHz Micropower Synchronous Boost Converter in ThinSOT U FEATURES DESCRIPTIO ■ The LTC®3400-1 is a synchronous, fixed frequency, stepup DC/DC converter delivering high efficiency in a 6-lead ThinSOT™ package. Capable of supplying 3.3V at 100mA from a single AA cell input, the device contains an internal NMOS switch and PMOS synchronous rectifier. ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Up to 92% Efficiency Generates 3.3V at 100mA from a Single AA Cell Low Start-Up Voltage: 0.85V VOUT Connected to VIN in Shutdown Internal Synchronous Rectifier 2.5V to 5V Output Range Automatic Burst Mode® Operation Logic Controlled Shutdown (< 1µA) Antiringing Control Minimizes EMI Tiny External Components Low Profile (1mm) SOT-23 Package A switching frequency of 1.2MHz minimizes solution footprint by allowing the use of tiny, low profile inductors and ceramic capacitors. The current mode PWM design is internally compensated, reducing external parts count. The LTC3400-1 features automatic shifting to power saving Burst Mode operation at light loads. In shutdown, VOUT and VIN are connected, which allows the input battery to be used for backup power. The LTC3400-1 features low shutdown current of under 1µA. U APPLICATIO S ■ ■ ■ ■ ■ ■ Pagers MP3 Players Digital Cameras LCD Bias Supplies Handheld Instruments Wireless Handsets GPS Receivers The LTC3400-1 is offered in the low profile (1mm) SOT-23 package. , LTC, LT and Burst Mode are registered trademarks of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. US Patent Numbers 5,481,178; 6,580,258; 6,304,066; 6,127,815; 6,498,466; 6,611,131. U ■ TYPICAL APPLICATIO Efficiency 100 Single Cell to 3.3V Synchronous Boost Converter 90 VIN = 2.4V + SINGLE AA CELL 4.7µF SW VIN VOUT LTC3400-1 OFF ON SHDN GND 1.02M 1% FB VOUT 3.3V 100mA EFFICIENCY (%) 4.7µH VIN = 1.5V 80 70 60 4.7µF 604k 1% 50 34001 F01 FIGURE 1 CIRCUIT WITH OPTIONAL SCHOTTKY DIODE (SEE APPLICATIONS INFORMATION) 40 0.1 1 10 100 LOAD CURRENT (mA) 1000 34001 F01a 34001f 1 LTC3400-1 W W W AXI U U ABSOLUTE RATI GS U U W PACKAGE/ORDER I FOR ATIO (Note 1) VIN Voltage ................................................. – 0.3V to 6V SW Voltage DC .......................................................... – 0.3V to 6V Pulsed (<100ns) ......................................– 0.3V to 7V SHDN, FB Voltage ....................................... – 0.3V to 6V VOUT ........................................................... – 0.3V to 6V Operating Temperature Range (Note 2) .. – 30°C to 85°C Storage Temperature Range ................... – 65°C to 125° Lead Temperature (Soldering, 10 sec).................. 300°C ORDER PART NUMBER TOP VIEW SW 1 GND 2 FB 3 6 VIN LTC3400ES6-1 5 VOUT 4 SHDN S6 PART MARKING S6 PACKAGE 6-LEAD PLASTIC TSOT-23 LTBJM TJMAX = 125°C, θJC = 102°C/W Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 1.2V, VOUT = 3.3V, unless otherwise specified. PARAMETER CONDITIONS Minimum Start-Up Voltage ILOAD = 1mA Minimum Operating Voltage SHDN = VIN (Note 4) MIN Output Voltage Adjust Range TYP MAX 0.85 1 0.5 0.65 V 5 V 1.268 V 2.5 ● Feedback Voltage 1.192 1.23 UNITS V Feedback Input Current VFB = 1.25V (Note 3) 1 Quiescent Current (Burst Mode Operation) VFB = 1.4V (Note 5) 19 30 µA Quiescent Current (Shutdown) VSHDN = 0V, Not Including Switch Leakage, VIN = VOUT 0.01 1 µA Quiescent Current (Active) Measured On VOUT 300 500 µA NMOS Switch Leakage VSW = 5V 0.1 5 µA PMOS Switch Leakage VSW = 0V (Note 3) 0.1 µA NMOS Switch On Resistance VOUT = 3.3V VOUT = 5V 0.35 0.20 Ω Ω PMOS Switch On Resistance VOUT = 3.3V VOUT = 5V 0.45 0.30 Ω Ω 850 mA NMOS Current Limit 600 nA Burst Mode Operation Current Threshold (Note 3) 3 mA Current Limit Delay to Output (Note 3) 40 ns Max Duty Cycle VFB = 1.15V ● 80 87 ● 0.95 0.85 1.2 1.2 Switching Frequency SHDN Input High MHz MHz 1 V SHDN Input Low SHDN Input Current % 1.5 1.5 VSHDN = 5.5V Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LTC3400-1 is guaranteed to meet performance specifications from 0°C to 70°C. Specifications over the – 30°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. 0.01 0.35 V 1 µA Note 3: Specification is guaranteed by design and not 100% tested in production. Note 4: Minimum VIN operation after start-up is only limited by the battery’s ability to provide the necessary power as it enters a deeply discharged state. Note 5: Burst Mode operation IQ is measured at VOUT. Multiply this value by VOUT/VIN to get the equivalent input (battery) current. 34001f 2 LTC3400-1 U W TYPICAL PERFOR A CE CHARACTERISTICS Output Load Burst Mode Threshold vs VIN Minimum Start-Up Voltage vs Load Current VOUT vs Temperature 3.36 L = 4.7µH TA = 25°C 1.4 FIGURE 1 CIRCUIT IO = 10mA 1.3 START-UP VOLTAGE (V) VOUT = 3.3V VOUT = 5V 3.32 VOUT (V) OUTPUT CURRENT (mA) 3.34 20 3.30 10 3.28 0.9 1.5 2.1 2.7 VIN (V) 3.3 3.9 3.24 –60 4.5 1.1 1.0 0.8 –30 0 30 60 TEMPERATURE (°C) 90 0.1 120 1 10 IOUT (mA) CURRENT SOURCE LOAD Normalized Oscillator Frequency vs Temperature No Load Battery Current vs VBATT 100 3400 G03 3400 G02 3400 G01 1000 1.2 0.9 3.26 0 TA = 25°C SW Pin Antiringing Operation 1.01 VOUT = 3.3V TA = 25°C NORMALIZED FREQUENCY BATTERY CURRENT (µA) 1.00 100 0.99 VSW 1V/DIV 0.98 0.97 0V 0.96 10 0.9 1.2 1.5 1.8 2.1 2.4 BATTERY VOLTAGE (V) 2.7 0.95 –50 –30 3.0 30 50 –10 10 TEMPERATURE (°C) SW Pin Fixed Frequency, Continuous Inductor Current Operation Fixed Frequency and Burst Mode Operation VSW 1V/DIV 3400 G07 3400 G06 VOUT Transient Response VOUT(AC) 100mV/DIV VOUT(AC) 100mV/DIV 60mA 100mA IOUT 40mA IOUT 0V 100ns/DIV 90 100ns/DIV 3400 G05 3400 G04 VIN = 1.3V VOUT = 3.3V IOUT = 50mA L = 6.8µH COUT = 4.7µF 70 VIN = 1.3V VOUT = 3.3V IOUT = 10mA L = 6.8µH COUT = 4.7µF 10µA VIN = 1.3V 10ms/DIV VOUT = 3.3V IOUT = 60mA TO 10µA L = 6.8µH COUT = 4.7µF 3400 G08 VIN = 1.3V 100µs/DIV VOUT = 3.3V IOUT = 40mA TO 100mA L = 6.8µH COUT = 4.7µF 3400 G09 34001f 3 LTC3400-1 U U U PI FU CTIO S SHDN = Low: Shutdown, quiescent current < 1µA. 100Ω connected between SW and VIN. VIN is connected to VOUT through the internal P-channel MOSFET synchronous rectifier and external inductor. SW (Pin 1): Switch Pin. Connect inductor between SW and VIN. Optional Schottky diode is connected between SW and VOUT. Keep these PCB trace lengths as short and wide as possible to reduce EMI and voltage overshoot. If the inductor current falls to zero, or SHDN is low, an internal 100Ω antiringing switch is connected from SW to VIN to minimize EMI. Typically, SHDN should be connected to VIN through a 1M pull-up resistor. VOUT (Pin 5): Output Voltage Sense Input and Drain of the Internal Synchronous Rectifier MOSFET. Bias is derived from VOUT. PCB trace length from VOUT to the output filter capacitor(s) should be as short and wide as possible. VOUT is connected to VIN in shutdown through the internal P-channel MOSFET synchronous rectifier. GND (Pin 2): Signal and Power Ground. Provide a short direct PCB path between GND and the (–) side of the output capacitor(s). FB (Pin 3): Feedback Input to the gm Error Amplifier. Connect resistor divider tap to this pin. The output voltage can be adjusted from 2.5V to 5V by: VIN (Pin 6): Battery Input Voltage. The device gets its start-up bias from VIN. Once VOUT exceeds VIN, bias comes from VOUT. Thus, once started, operation is completely independent from VIN. Operation is only limited by the output power level and the battery’s internal series resistance. VOUT = 1.23V • [1 + (R1/R2)] SHDN (Pin 4): Logic Controlled Shutdown Input. SHDN = High: Normal free running operation, 1.2MHz typical operating frequency. W BLOCK DIAGRA L1 4.7µH SINGLE CELL INPUT CIN 1µF 6 VIN 1 SW OPTIONAL SCHOTTKY + + VOUT GOOD – START-UP OSC A 2.3V A/B MUX PWM CONTROL RAMP GEN 1.2MHz 3.3V OUTPUT VOUT 0.45Ω B 5 SYNC DRIVE CONTROL SHUTDOWN CURRENT SENSE Σ SLOPE COMP 0.35Ω R1 1.02M 1% (EXTERNAL) CFF (OPTIONAL) PWM COMPARATOR – – + FB – SLEEP Burst Mode OPERATION CONTROL CC 150pF SHDN 4 SHUTDOWN CONTROL SHUTDOWN + RC 80k gm ERROR AMP CP2 2.5pF COUT 4.7µF 3 1.23V REF R2 604k 1% (EXTERNAL) 2 GND 34001 BD 34001f 4 LTC3400-1 U OPERATIO The LTC3400-1 is a1.2MHz, synchronous boost converter housed in a 6-lead ThinSOT package. Able to operate from an input voltage below 1V, the device features fixed frequency, current mode PWM control for exceptional line and load regulation. With its low RDS(ON) and gate charge internal MOSFET switches, the device maintains high efficiency over a wide range of load current. Detailed descriptions of the three distinct operating modes follow. Operation can be best understood by referring to the Block Diagram. Low Voltage Start-Up The LTC3400-1 will start up at a typical VIN voltage of 0.85V or higher. The low voltage start-up circuitry controls the internal NMOS switch up to a maximum peak inductor current of 850mA (typ), with an approximate 1.5µs offtime during start-up, allowing the device to start up into an output load. Once VOUT exceeds 2.3V, the start-up circuitry is disabled and normal fixed frequency PWM operation is initiated. In this mode, the LTC3400-1 operates independent of VIN, allowing extended operating time as the battery can droop to several tenths of a volt without affecting output voltage regulation. The limiting factor for the application becomes the ability of the battery to supply sufficient energy to the output. Low Noise Fixed Frequency Operation Oscillator: The frequency of operation is internally set to 1.2MHz. Error Amp: The error amplifier is an internally compensated transconductance type (current output) with a transconductance (gm) = 33 microsiemens. The internal 1.23V reference voltage is compared to the voltage at the FB pin to generate an error signal at the output of the error amplifier. A voltage divider from VOUT to ground programs the output voltage via FB from 2.5V to 5V using the equation: VOUT = 1.23V • [1 + (R1/R2)] Current Sensing: A signal representing NMOS switch current is summed with the slope compensator. The summed signal is compared to the error amplifier output to provide a peak current control command for the PWM. Peak switch current is limited to approximately 850mA independent of input or output voltage. The current signal is blanked for 40ns to enhance noise rejection. Zero Current Comparator: The zero current comparator monitors the inductor current to the output and shuts off the synchronous rectifier once this current reduces to approximately 20mA. This prevents the inductor current from reversing in polarity improving efficiency at light loads. Antiringing Control: The antiringing control circuitry prevents high frequency ringing of the SW pin as the inductor current goes to zero by damping the resonant circuit formed by L and CSW (capacitance on SW pin). Burst Mode Operation Portable devices frequently spend extended time in low power or standby mode, only switching to high power drain when specific functions are enabled. In order to improve battery life in these types of products, high power converter efficiency needs to be maintained over a wide output power range. In addition to its high efficiency at moderate and heavy loads, the LTC3400-1 includes automatic Burst Mode operation that improves efficiency of the power converter at light loads. Burst mode operation is initiated if the output load current falls below an internally programmed threshold (see Typical Performance graph, Output Load Burst Mode Threshold vs V IN). Once initiated, the Burst Mode operation circuitry shuts down most of the device, only keeping alive the circuitry required to monitor the output voltage. This is referred to as the sleep state. In sleep, the LTC3400-1 draws only 19µA from the output capacitor, greatly enhancing efficiency. When the output voltage has drooped approximately 1% from nominal, the LTC3400-1 wakes up and commences normal PWM operation. The output capacitor recharges and causes the LTC3400-1 to reenter sleep if the output load remains less than the sleep threshold. The frequency of this intermittent PWM or burst operation is proportional to load current; that is, as the load current drops further below the burst threshold, the LTC3400-1 turns on less frequently. When the load current increases 34001f 5 LTC3400-1 U OPERATIO above the burst threshold, the LTC3400-1 will resume continuous PWM operation seamlessly. Referring to the Block Diagram, an optional capacitor (CFF) between VOUT and FB in some circumstances can reduce the peak-to- peak VOUT ripple and input quiescent current during Burst Mode operation. Typical values for CFF range from 15pF to 220pF. U W U U APPLICATIO S I FOR ATIO PCB LAYOUT GUIDELINES The high speed operation of the LTC3400-1 demands careful attention to board layout. You will not get advertised performance with careless layout. Figure 1 shows the recommended component placement. A large ground pin copper area will help to lower the chip temperature. A multilayer board with a separate ground plane is ideal, but not absolutely necessary. will allow greater output current capability by reducing the inductor ripple current. Increasing the inductance above 10µH will increase size while providing little improvement in output current capability. The approximate output current capability of the LTC3400-1 versus inductance value is given in the equation below and illustrated graphically in Figure 2. VIN =1.2V 180 VIN 1 SW 2 GND VOUT 5 3 OUTPUT CURRENT (mA) (OPTIONAL) VIN 6 FB SHDN 4 SHDN VOUT = 3V VOUT = 3.3V 160 VOUT = 3.6V 140 120 VOUT = 5V 110 80 60 VOUT 3 5 7 9 11 13 15 17 19 21 23 INDUCTANCE (µH) 34001 F03 34001 F02 RECOMMENDED COMPONENT PLACEMENT. TRACES CARRYING HIGH CURRENT ARE DIRECT. TRACE AREA AT FB PIN IS SMALL. LEAD LENGTH TO BATTERY IS SHORT Figure 1. Recommended Component Placement for Single Layer Board COMPONENT SELECTION Inductor Selection The LTC3400-1 can utilize small surface mount and chip inductors due to its fast 1.2MHz switching frequency. A minimum inductance value of 3.3µH is necessary for 3.6V and lower voltage applications and 4.7µH for output voltages greater than 3.6V. Larger values of inductance Figure 2. Maximum Output Current vs Inductance Based On 90% Efficiency V •D⎞ ⎛ IOUT(MAX) = η • ⎜IP – IN ⎟ • (1 – D) ⎝ f • L • 2⎠ where: η = estimated efficiency IP = peak current limit value (0.6A) VIN = input (battery) voltage D = steady-state duty ratio = (VOUT – VIN)/VOUT f = switching frequency (1.2MHz typical) L = inductance value 34001f 6 LTC3400-1 U W U U APPLICATIO S I FOR ATIO The inductor current ripple is typically set for 20% to 40% of the maximum inductor current (IP). High frequency ferrite core inductor materials reduce frequency dependent power losses compared to cheaper powdered iron types, improving efficiency. The inductor should have low ESR (series resistance of the windings) to reduce the I2R power losses, and must be able to handle the peak inductor current without saturating. Molded chokes and some chip inductors usually do not have enough core to support the peak inductor currents of 850mA seen on the LTC3400-1. To minimize radiated noise, use a toroid, pot core or shielded bobbin inductor. See Table 1 for some suggested components and suppliers. Table 1. Recommended Inductors PART L (µH) MAX DCR mΩ HEIGHT (mm) 2.0 2.0 1.8 1.8 3.5 3.5 0.8 0.8 Sumida (847) 956-0666 www.sumida.com VENDOR extremely low ESR and are available in small footprints. A 2.2µF to 10µF output capacitor is sufficient for most applications. Larger values up to 22µF may be used to obtain extremely low output voltage ripple and improve transient response. An additional phase lead capacitor may be required with output capacitors larger than 10µF to maintain acceptable phase margin. X5R and X7R dielectric materials are preferred for their ability to maintain capacitance over wide voltage and temperature ranges. Low ESR input capacitors reduce input switching noise and reduce the peak current drawn from the battery. It follows that ceramic capacitors are also a good choice for input decoupling and should be located as close as possible to the device. A 4.7µF input capacitor is sufficient for virtually any application. Larger values may be used without limitations. Table 2 shows a list of several ceramic capacitor manufacturers. Consult the manufacturers directly for detailed information on their entire selection of ceramic parts. CDRH5D18-4R1 CDRH5D18-100 CDRH3D16-4R7 CDRH3D16-6R8 CR43-4R7 CR43-100 CMD4D06-4R7MC CMD4D06-3R3MC 4.1 10 4.7 4.7 10 4.7 3.3 57 124 105 170 109 182 216 174 DS1608-472 DS1608-103 DO1608C-472 4.7 10 4.7 60 75 90 2.9 2.9 2.9 Coilcraft (847) 639-6400 www.coilcraft.com D52LC-4R7M D52LC-100M 4.7 10 84 137 2.0 2.0 Toko (408) 432-8282 www.tokoam.com Output Diode LQH3C4R7M24 4.7 195 2.2 Murata www.murata.com Table 2. Capacitor Vendor Information Output and Input Capacitor Selection Low ESR (equivalent series resistance) capacitors should be used to minimize the output voltage ripple. Multilayer ceramic capacitors are an excellent choice as they have SUPPLIER PHONE WEBSITE AVX (803) 448-9411 www.avxcorp.com Murata (714) 852-2001 www.murata.com Taiyo Yuden (408) 573-4150 www.t-yuden.com Use a Schottky diode such as an MBR0520L, PMEG2010EA, 1N5817 or equivalent if the converter output voltage is 4.5V or greater. The Schottky diode carries the output current for the time it takes for the synchronous rectifier to turn on. Do not use ordinary rectifier diodes, since the slow recovery times will compromise efficiency. A Schottky diode is also strongly recommended for output voltages below 4.5V, and will increase converter efficiency by 2% to 3%. 34001f 7 LTC3400-1 U TYPICAL APPLICATIO S Single Cell to 3.3V Synchronous Boost Converter with Load Disconnect in Shutdown L1 4.7µH + SINGLE AA CELL C1 4.7µF D1 1 6 SW VIN VOUT 5 LTC3400-1 OFF ON 4 SHDN FB GND 2 D1: PHILLIPS PMEG2010EA L1: SUMIDA CDRH2D18/HP-4R7 R3 510k M1 Si2305DS R3 510k R1 1.02M 1% C2 4.7µF R2 604k 1% 3 VOUT 3.3V 100mA Q1 2N3904 34001 TA01a 34001f 8 LTC3400-1 U TYPICAL APPLICATIO S Single Lithium Cell to 5V, 250mA OPTIONAL SNUBBER 2Ω 1nF L1 4.7µH + LITHIUM CELL C1 4.7µF D1 1 6 SW VIN VOUT 5 LTC3400-1 OFF ON 4 SHDN FB 3 C2 4.7µF GND 2 D1: PHILIPS PMEG2010EA L1: SUMIDA CDRH2D18/HP-4R7 C1, C2: TAIYO YUDEN JMK212BJ475MG R1 1.02M 1% C3 100pF R2 332k 1% 34001 TA02a 3.6V to 5V Efficiency 100 EFFICIENCY (%) 90 LTC3400-1 CO = 4.7µF L = 4.7µH 80 70 60 50 0.1 1 10 100 LOAD CURRENT (mA) 1000 34001 TA02b 34001f 9 LTC3400-1 U TYPICAL APPLICATIO S Single Cell AA Cell to ±3V Synchronous Boost Converter C3 1µF L1 4.7µH + SINGLE AA CELL C1 4.7µF 1 6 SW VIN VOUT 5 LTC3400-1 OFF ON 4 FB SHDN GND 2 3 R1 1.02M 1% R2 715k 1% D1 D2 VOUT1 3V C2 90mA 4.7µF C4 10µF 34001 TA03a VOUT2 –3V 10mA D1, D2: ZETEX FMND7000 DUAL DIODE L1: SUMIDA CDRH2D18/HP-4R7 34001f 10 LTC3400-1 U PACKAGE DESCRIPTIO S6 Package 6-Lead Plastic TSOT-23 (Reference LTC DWG # 05-08-1636) 0.62 MAX 2.90 BSC (NOTE 4) 0.95 REF 1.22 REF 3.85 MAX 2.62 REF 1.4 MIN 2.80 BSC 1.50 – 1.75 (NOTE 4) PIN ONE ID RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR 0.30 – 0.45 6 PLCS (NOTE 3) 0.95 BSC 0.80 – 0.90 0.20 BSC 0.01 – 0.10 1.00 MAX DATUM ‘A’ 0.30 – 0.50 REF 0.09 – 0.20 (NOTE 3) 1.90 BSC S6 TSOT-23 0302 NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3. DIMENSIONS ARE INCLUSIVE OF PLATING 4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 5. MOLD FLASH SHALL NOT EXCEED 0.254mm 6. JEDEC PACKAGE REFERENCE IS MO-193 34001f Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 11 LTC3400-1 U TYPICAL APPLICATIO Single AA Cell to 2.5V Synchronous Boost Converter L1 3.3µH + SINGLE AA CELL C1 4.7µF D1 1 6 SW VIN VOUT LTC3400-1 OFF ON 4 SHDN FB 3 GND D1: PHILIPS PMEG2010EA L1: SUMIDA CDRH2D18/HP-3R7 VOUT 2.5V 130mA 5 2 R1 1.02M 1% R2 1M 1% C2 4.7µF 34001 TA04a RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1308A/LT1308B High Current, Micropower, Single Cell 600kHz DC/DC Converter 5V at 1A with Single Li-Ion Cell, VOUT to 34V LT1613 1.4MHz, Single Cell DC/DC Converter in ThinSOT VIN as Low as 1.1V, 3V at 30mA from Single Cell LT1615 Micropower Step-Up DC/DC Converter in ThinSOT IQ = 20µA, 1µA Shutdown Current, VIN as Low as 1V LT ®1618 1.4MHz Step-Up DC/DC Converter with Current Limit 1.5A Switch, 1.6V to 18V Input Range, Input or Output Current Limiting LT1619 High Efficiency Boost DC/DC Controller 1A Gate Drive, 1.1V to 20V Input, Separate VCC for Gate Drive LTC1872 ThinSOT Boost DC/DC Controller 50kHz, 2.5V to 9.8V Input LT1930/LT1930A 1.2MHz/2.2MHz DC/DC Converters in ThinSOT VIN = 2.6V to 16V, 5V at 450mA from 3.3V Input LT1932 Constant Current Step-Up LED Driver Drives Up to Eight White LEDs, ThinSOT Package LT1946/LT1946A 1.2MHz/2.7MHz Boost DC/DC Converters 1.5A, 36V Internal Switch, 8-Pin MSOP Package LT1949 600kHz, 1A Switch PWM DC/DC Converter 1A, 0.5Ω, 30V Internal Switch, VIN as Low as 1.5V, Low-Battery Detect Active in Shutdown LTC3400/LTC3400B 600mA, 1.2MHz Synchronous Boost Converters in ThinSOT Up to 92% EFFiciency, 600mA Switch, No Burst Option (LTC3400B) LTC3401 1A, 3MHz Micropower Synchronous Boost Converter 1A Switch, Programmable Frequency, 10-Pin MSOP Package LTC3402 2A, 3MHz Micropower Synchronous Boost Converter 2A Switch, Programmable Frequency, 10-Pin MSOP Package LTC3421 3A, 3MHz Micropower Synchronous Boost Converter Up to 96% Efficiency, 3A Switch, True Output Disconnect, 4mm x 4mm QFN Package LTC3423 1A, 3MHz Micropower Synchronous Boost Converter 1A Switch, Separate Bias Pin for Low Output Voltages LTC3424 2A, 3MHz Micropower Synchronous Boost Converter 2A Switch, Separate Bias Pin for Low Output Voltages LTC3425 5A, 8MHz, 4-Phase Micropower Synchronous Boost Converter Up to 95% Efficiency, 5A Switch, True Output Disconnect, IQ = 12µA, QFN Package LTC3429 600mA, 500kHz Synchronous Boost Converter in ThinSOT Up to 96% Efficiency, 600mA Switch, True Output Disconnect, Soft Start 34001f 12 Linear Technology Corporation LT/TP 0604 1K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2004