LTC3531/ LTC3531-3.3/LTC3531-3 200mA Buck-Boost Synchronous DC/DC Converters FEATURES DESCRIPTIOU ■ Regulated Output with Input Above, Below or Equal The LTC®3531/LTC3531-3.3/LTC3531-3 are synchronous to the Output buck-boost DC/DC converters that operate from input ■ Single Inductor voltages above, below or equal to the output voltage. The ■ Up to 90% Effi ciency topology incorporated in the ICs provides a continuous ■ VIN Range: 1.8V to 5.5V transfer through all operating modes, making the product ■ 200mA at 3.3VOUT from 3.6V Input ideal for single cell Li-Ion and multicell alkaline or nickel ■ 125mA at 3VOUT from 2.5V Input applications. The converters operate in Burst Mode, mini- ■ Fixed VOUT Versions (TSOT, DFN): 3.3V, 3V mizing solution footprint and component count as well as ■ Adjustable VOUT Version (DFN): 2V to 5V providing high conversion effi ciency over a wide range of ■ Burst Mode® Operation, No External Compensation load currents. ■ Ultra Low Quiescent Current: 16μA, Shutdown The devices include two 0.5Ω N-channel MOSFET switches Current <1μA and two P-channel switches (0.5Ω, 0.8Ω). Quiescent ■ Only 3 External Components Required current is typically 16μA, making the parts ideal for bat- (Fixed Voltage Versions) tery power applications. Other features include a <1μA ■ Short-Circuit Protection shutdown current, current limiting, thermal shutdown ■ Output Disconnect in Shutdown and output disconnect. The parts are offered in a 6-pin ■ Available in 6-Pin ThinSOT and 3mm × 3mm DFN ThinSOTTM package for fi xed voltage versions or a 3mm × Packages 3mm DFN package for fi xed and adjustable versions. APPLICATIOUS , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation. ■ Handheld Instruments ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. ■ MP3 Players Protected by U.S. Patents including 6166527. ■ Handheld computers ■ PDA/GPS TYPICAL APPLICATIOU Effi ciency vs V IN 100 10μH 95 90 BOOST 3.1V4 V.T2IOVN VSIWN1 VSOWU2T V31.6O30UVmTA CY (%) 85 MODE MBUOCDKE LTC3531-3.3 N 80 Li-Ion + 2.2μF 10μF FFICIE 75 M4OSWDE E SHDN GND 70 3531 TA01a 65 ON OFF 3.3VOUT AT 100mA 60 1.5 2 2.5 3 3.5 4 4.5 5 5.5 INPUT VOLTAGE (V) 3531 TA01b 3531fb 1

LTC3531/ LTC3531-3.3/LTC3531-3 ABSOLUTE WAXIWUWRATIUGS (Note 1) VIN, VOUT, SW1, SW2, SHDN Voltage ...........–0.3 to 6V Storage Temperature Range ...................–65°C to 125°C SW1, SW2 Voltage, <100ns Pulse ..................–0.3 to 7V Lead Temperature (TS6, Soldering, 10 sec) ..........300°C Operating Temperature Range (Notes 2, 3) –40°C to 85°C PACKAGE/ORDER IUFORWATIOU TOP VIEW TOP VIEW SW1 1 8 PGND SW2 1 6 SW1 VIN 2 9 7 SW2 GND, PGND 2 5 VIN GND 3 6 VOUT VOUT 3 4 SHDN SHDN 4 5 FB* S6 PACKAGE DD PACKAGE 6-LEAD PLASTIC TSOT-23 8-LEAD (3mm × 3mm) PLASTIC DFN TJMAX = 125°C, θJA = 102°C/W TJMAX = 125°C, θJA = 43°C/W EXPOSED PAD IS GND (PIN 9), MUST BE SOLDERED TO PCB *NC FOR LTC3531-3.3V, LTC3531-3.0V. ORDER PART NUMBER S6 PART MARKING ORDER PART NUMBER DD PART MARKING LTC3531ES6-3.3 LTBWM LTC3531EDD LBVC LTC3531ES6-3 LTCBK LTC3531EDD-3.3 LBWH LTC3531EDD-3 LCBV Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The ● denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at T = 25°C. V = 3.6V V = 3.3V unless otherwise noted. A IN OUT PARAMETER CONDITIONS MIN TYP MAX UNITS V IN Minimum Startup Voltage ● 1.65 1.8 V V Regulation OUT Output Voltage (3.3V Version) No Load ● 3.25 3.32 3.39 V Output Voltage (3V Version) No Load ● 2.95 3.02 3.09 V FB Voltage (Adj Version) No Load ● 1.20 1.225 1.25 V FB Input Current (Adj Version) V = 1.225V 1 50 nA FB Operating Current Quiescent Current in Sleep: V V = 5V, V = 3.6V, FB = 1.3V 16 30 μA IN IN OUT V V = 3.6V 6 10 μA OUT OUT Shutdown Current VIN SHDN = 0V, VOUT = 0V 1 μA Switch Performance NMOS Switch Leakage Switches B and C 0.2 2 μA PMOS Switch Leakage Switches A and D 0.2 2 μA NMOS B, C RDSON VIN = 5V 0.5 Ω PMOS A RDSON VIN = 5V 0.5 Ω 3531fb 2

LTC3531/ LTC3531-3.3/LTC3531-3 ELECTRICAL CHARACTERISTICS The ● denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at T = 25°C. V = 3.6V V = 3.3V unless otherwise noted. A IN OUT PARAMETER CONDITIONS MIN TYP MAX UNITS PMOS D RDSON (3.3V Version or Adjustable Version set to 3.3V) VOUT = 3.1V 0.8 Ω PMOS D RDSON (3V Version) VOUT = 2.8V 0.9 Ω Peak Current Limit L = 10μH, VIN = 5V 295 365 460 mA SHDN SHDNInput Threshold 0.4 1 1.4 V SHDNHysteresis 60 mV SHDNLeakage Current VSHDN 0.01 1 μA Note 1: Stresses beyond those listed under Absolute Maximum Ratings Continuous operation above the specifi ed maximum operating junction may cause permanent damage to the device. Exposure to any Absolute temperature may result in device degradation or failure. Maximum Rating condition for extended periods may affect device Note 3: The LTC3531 is guaranteed to meet performance specifi cations reliability and lifetime. from 0°C to 70°C. Specifi cations over the –40°C to 85°C operating Note 2: This IC includes overtemperature protection that is intended temperature range are assured by design, characterization and correlation to protect the device during momentary overload conditions. Junction with statistical process controls. temperature will exceed 125°C when overtemperature protection is active. TYPICAL PERFORWAUCE CHARACTERISTICS T = 25°C unless otherwise specifi ed. A Maximum I vs V OUT IN (3.3V Version) I , I , I vs V Sleep Currents PEAK VALLEY ZERO IN 350 450 20 L = 10μH L = 10μH VOUT = 3.3V 400 18 300 350 IPEAK 16 IVIN MAXIMUM I (mA)OUT211205050000 CURRENT (mA) 213255000000 IVALLEY μCURRENT (A) 11126804 IVOUT 100 4 50 50 IZERO 2 0 0 0 1.5 2 2.5 3 3.5 4 4.5 5 5.5 1.5 2 2.5 3 3.5 4 4.5 5 5.5 1.5 2 2.5 3 3.5 4 4.5 5 5.5 VIN (V) VIN (V) VIN (V) 3531 G01 3531 G02 3531 G03 V Ripple vs C Load Regulation vs C OUT OUT OUT I Short Circuit vs V (3.3V Version) (3.3V Version) IN IN 180 100 3.40 160 90 10μF 140 80 10μF 3.35 I (mA)IN1106280000 (mV)RIPPLE PEAK-PEAK 6345700000 22μF V (V)OUT33..2350 22μF 47μF V 40 20 3.20 20 10 50mA LOAD VIN = 3.6V 0 0 3.15 1.5 2 2.5 3 3.5 4 4.5 5 5.5 1.5 2 2.5 3 3.5 4 4.5 5 5.5 0.1 1 10 100 1000 VIN (V) VIN (V) LOAD CURRENT (mA) 3531 G04 3531 G05 3521 G06 3531fb 3

LTC3531/ LTC3531-3.3/LTC3531-3 TYPICAL PERFORW AU CE CHARACTERISTICS T = 25°C unless otherwise specifi ed. A Start-Up into Resistive Load Burst Frequency vs Load V Regulation vs Temperature OUT L = 10μH (3.3V Version) (3.3V Version) 30 1000 3.350 L = 10μH VIN = 3.6V 28 COUT = 10μF ILOAD = 10mA 26 100 3.325 24 50mA Hz) 10mA ΩR()MIN 212280 QUENCY (k 10 5mA V (V)OUT3.300 E 1mA R 16 F 1 3.275 14 0.5mA 12 10 0.1 3.250 1.5 2 2.5 3 3.5 4 4.5 5 5.5 1.5 2 2.5 3 3.5 4 4.5 5 5.5 –40 –20 0 20 40 60 80 100 VIN (V) VIN (V) TEMPERATURE (°C) 3531 G07 3531 G08 3531 G09 SHDN Pin Threshold and Switch On Resistances I , I vs Temperature Hysteresis PEAK VALLEY 1000 400 1 VIN = 5V IPEAK VOUT = 3.3V D (PMOS) 350 900 0.9 300 800 Ω (m)SON700 RENT (mA) 220500 IVALLEY LTAGE (V) 0.8 OPERATING RD A (PMOS) UR 150 VO 0.7 SHUTDOWN 600 C 2.5VIN 100 3.3VOUT 500 10μH 0.6 B,C (NMOS) 50 IZERO 400 0 0.5 –40 –20 0 20 40 60 80 100 –40 –20 0 20 40 60 80 100 –40 –20 0 20 40 60 80 100 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) 3531 G10 3531 G11 3531 G12 3531fb 4

LTC3531/ LTC3531-3.3/LTC3531-3 TYPICAL PERFORW AU CE CHARACTERISTICS T = 25°C unless otherwise specifi ed. A Buck Mode at 5V , Buck Mode at 5V , IN IN 3.3V 200mA 3.3V 100mA OUT OUT SW1 SW1 5V/DIV 5V/DIV SW2 SW2 5V/DIV 5V/DIV VOUT (AC) VOUT (AC) 50mV/DIV 50mV/DIV IL IL 200mA/DIV 200mA/DIV L = 10μH 5μs/DIV 3531 G13 L = 10μH 5μs/DIV 3531 G14 COUT = 22μF COUT = 22μF Buck Mode Waveforms at 5V , 4 Switch Mode Waveforms at IN 3.3V 20mA 3.6V , 3.3V 200mA OUT IN OUT SW1 SW1 5V/DIV 5V/DIV SW2 SW2 5V/DIV 5V/DIV VOUT (AC) VOUT (AC) 50mV/DIV 50mV/DIV IL IL 200mA/DIV 200mA/DIV L = 10μH 5μs/DIV 3531 G15 L = 10μH 5μs/DIV 3531 G16 COUT = 22μF COUT = 22μF 4 Switch Mode Waveforms at 4 Switch Mode Waveforms at 3.6VIN, 3.3VOUT 100mA 3.6VIN, 3.3VOUT 20mA SW1 SW1 5V/DIV 5V/DIV SW1 SW2 SW2 5V/DIV 5V/DIV SW2 VOUT (AC) VOUT (AC) 50mV/DIV 50mV/DIV VOUT (AC) IL IL 200mA/DIV 200mA/DIV IL L = 10μH 5μs/DIV 3531 G17 L = 10μH 5μs/DIV 3531 G18 COUT = 22μF COUT = 22μF 3531fb 5

LTC3531/ LTC3531-3.3/LTC3531-3 TYPICAL PERFORW AU CE CHARACTERISTICS T = 25°C unless otherwise specifi ed. A Boost Mode Waveforms at Boost Mode Waveforms at 2.5V , 3.3V 100mA 2.5V , 3.3V 20mA IN OUT IN OUT SW1 SW1 5V/DIV 5V/DIV SW2 SW2 5V/DIV 5V/DIV VOUT (AC) VOUT (AC) 50mV/DIV 50mV/DIV IL IL 200mA/DIV 200mA/DIV L = 10μH 5μs/DIV 3531 G19 L = 10μH 5μs/DIV 3531 G20 COUT = 22μF COUT = 22μF Start-Up into 50mA Load at 3.3 V (Shows Start, Buck, OUT Shorted Output Then 4sw Modes) SW1 5V/DIV SW2 5V/DIV 5V0OmUTV (/ADCIV) 200mA/DIV 1VV/DOUIVT 200mA/DIIVL 200mA/DIIVL L = 10μH 1μs/DIV 3531 G21 25μs/DIV 3531 G22 COUT = 22μF VIN = 5 3.6V , 3.3V Load Step SW1 and SW2 Close-Up in Four IN OUT 200mA to 80mA Switch Mode 100mA LOAD SW1 20mA LOAD 20mA LOAD 2V/DIV IL VOUT (AC) 200mA/DIV 20mV/DIV SW2 2V/DIV COUT = 22μF 25μs/DIV 3531 G23 VIN = 3.6V 200ns/DIV 3531 G24 VOUT = 3.3V 3531fb 6

LTC3531/ LTC3531-3.3/LTC3531-3 PIU FUUCTIOUS ThinSOT/DFN Packages SW2 (Pin 1/Pin 7): Buck-Boost Switch Pin Where Internal V (Pin 5/Pin 2): Input Supply Pin for the Buck-Boost IN Switches C and D are Connected. An optional Schottky Converter. A minimum 2.2μF Ceramic Capacitor should diode can be connected from SW2 to V for a moderate be placed between V and GND. OUT IN effi ciency improvement. Minimize trace length to keep FB (NA/Pin 5): Feedback Pin for the Adjustable Version. EMI down. Connect the resistor divider tap here. The output voltage GND (Pin 2/Pin 3): Signal Ground for the IC. can be adjusted from 2V to 5V. PGND (Pin 2/Pin 8): Power Ground for the IC. (Shared ⎛ R2⎞ V =1.225⎜1+ ⎟ on ThinSOT version) OUT ⎝ R1⎠ V (Pin 3/Pin 6): Output of the Buck-Boost Synchronous OUT SW1 (Pin 6/Pin 1): Buck-Boost Switch Pin Where Internal Rectifi er. A fi lter capacitor is placed from V to GND. OUT Switches A and B are Connected. Connect the inductor A ceramic bypass capacitor is recommended as close to from SW1 to SW2. the V and GND pins as possible. OUT Exposed Pad (Pin 9, DFN): Solder to PCB ground for SHDN (Pin 4/Pin 4): External Shutdown Pin. An applied optimal thermal performance. voltage of < 0.4V shuts down the converter. A voltage above >1.4V will enable the converter. 3531fb 7

LTC3531/ LTC3531-3.3/LTC3531-3 BLOCK DIAGRAW SW1 SW2 SW A SW D VIN VOUT GATE DRIVERS AND ANTICROSS SW B CONDUCTION SW C IZERO/IVALLEY DETECT PEAK VBEST CURRENT VIN LIMIT VBEST 365mA BUCK, 4SW, AND BOOST MODE DETECT VOUT STATE MACHINE AND VIN LOGIC R2 UVLO 1.225V VREF 1.65V VOUT FB COMPARATOR R1 NOT BONDED SHDN SHUTDOWN STHHUETRDMOAWLN F3OVR V E3R.3SVI OANNSD INTERNAL 3531 BD PGND GND R1 AND R2 COMBINED DISABLED FOR TSOT FOR ADJ VERSION 3531fb 8

LTC3531/ LTC3531-3.3/LTC3531-3 OPERATIOU The LTC3531, LTC3531-3.3 and LTC3531-3 synchro- occurs, C is turned off, D is turned on and current is deliv- nous buck-boost converters utilize a Burst Mode control ered to the output capacitor (V – V is applied across IN OUT technique to achieve high effi ciency over a wide dynamic the inductor). Inductor current falls when D is on, until an range of load currents. A 2% accurate comparator is I is detected. Terminating at I , rather than I , VALLEY VALLEY ZERO used to monitor the output voltage. If V is above its results in an increased load current capability for a given OUT programmed reference threshold no switching occurs and peak current. This AC then AD switch sequence is repeated only quiescent current is drawn from the power source until the output is pumped above its regulation voltage, a (sleep mode). When V drops below the reference fi nal I is detected, and the part returns to sleep mode OUT ZERO threshold the IC “wakes up”, switching commences, and (I is ignored and I is used in all modes once VALLEY ZERO the output capacitor is charged. The value of the output V is above its programmed value). OUT capacitor, the load current, and the comparator hysteresis (~1%) determines the number of current pulses required 4-Switch Mode to pump-up the output capacitor before the part returns If (V – 400mV) < ~V < (V + 800mV), the LTC3531 OUT IN OUT to sleep. operates in 4-switch step-up/down mode. Returning to In order to determine the best operating mode for the Figure 1 (center) when VOUT falls below its regulation volt- converter, the LTC3531 contains a second comparator age, switches A and C are turned on and current is ramped that monitors the relative voltage difference between VIN until IPEAK is detected. As with Boost Mode operation, C and V . Input and output voltages in the various modes is then turned off, D is turned on and current is delivered OUT as well as typical inductor currents are shown in Figure 1. to the output. When A and D are on, the inductor current Regions of the current waveforms where switches A and slope is dependant on the relationship between VIN, VOUT, D are on provide the highest effi ciency since energy is and the RDSON of the switches. In 4-switch mode, a tOFF transferred directly from the input source to the output. timer (approximately 3μs) is used to terminate the AD pulse. Once the t timer expires, switch A is turned off, OFF Boost Mode B is turned on and inductor current is ramped down (V OUT is applied across the inductor) until I is detected. If V is ~400mV below V , the LTC3531 operates in VALLEY IN OUT This sequence is repeated until the output is regulated, boost or step-up mode. Referring to Figure 1 (left side) BD switches are turned on, and a fi nal I is detected. when V falls below its regulation voltage, switches A ZERO OUT Anticross conduction circuitry in all modes ensures the and C are turned on (V is applied across the inductor) IN P-channel MOSFET and N-channel MOSFET switch pairs (A and current is ramped until I is detected. When this PEAK and B or D and C) are never turned on simultaneously. VIN VOUT VIN VOUT A D VIN L SW1 SW2 IMAX B C IPEAK tOFF tOFF tOFF IVALLEY IZERO AC AD AC AD AC AD BDAC AD BDAC AD BD AD BD AD BD BOOST MODE 4SW MODE BUCK MODE 3531 F01 Figure 1. Voltage and Current Waveforms 3531fb 9

LTC3531/ LTC3531-3.3/LTC3531-3 OPERATIOU Buck Mode threshold is reached, the LTC3531 will transfer through the required modes until V is brought into regulation. If V is ~800mV above V , the LTC3531 operates in OUT IN OUT buck or step-down mode. The higher offset between V Due to propagation delays in the sense circuitry, the IN and V (800mV) is required to ensure suffi cient mag- magnitudes of the I , I , and I currents may OUT PEAK VALLEY ZERO netizing voltage across the inductor when the R shift depending on V , V and operating mode. DSONS IN OUT are taken into account. At the beginning of a buck mode cycle (Figure 1 right side) switches A and D are turned OTHER LTC3531 FEATURES on (V – V is applied across the inductor), current IN OUT Shutdown: The part is shut down by pulling SHDN below is delivered to the output and ramped up until I is PEAK 0.4V, and made active by pulling the pin up to V or V . IN OUT detected. When this occurs, A is turned off, B is turned Note that SHDN an be driven above V or V , as long IN OUT on and inductor current falls (–V across the induc- OUT as it is limited to less than 6V. tor) until an I is detected. This AD then BD switch VALLEY sequence is repeated until the output is pumped above Output Disconnect and Inrush Limiting: The LTC3531 its regulation voltage, a fi nal I is detected, and the is designed to allow true output disconnect by opening ZERO part returns to sleep mode. both P-channel MOSFET rectifi ers. This allows VOUT to go to zero volts during shutdown, drawing no current from Start-Up Mode the input source. It also provides inrush current limiting at turn-on, minimizing surge currents seen by the input Before V reaches approximately 1.6V, the D switch is OUT supply. disabled and its body diode is used to transfer current to the output capacitor. In start-up mode, the I /I Thermal Shutdown: If the die temperature reaches ap- VALLEY ZERO sense circuit is disabled and an alternate algorithm is used proximately 150°C, the part will go into thermal shut- to control inductor current. When the LTC3531 is brought down and all switches will be turned off. The part will be out of shutdown (assuming V is discharged) switches enabled again when the die temperature has dropped by OUT A and C are turned on until the inductor current reaches 10°C (nominal). To deliver the power that the LTC3531 I . The AC switches are then turned off and inductor is capable of, it is imperative that a good thermal path be PEAK current fl ows to the output through the B switch and D provided to dissipate the heat generated within the pack- body diode. The period for the B switch/D body diode is age. It is recommended that multiple vias in the printed controlled by the t timer to ~800nS. This sequence of circuit board be used to conduct heat away from the IC OFF AC switch-on to I then B switch and D body diode for and into a copper plane with as much area as possible. PEAK ~800ns is repeated until V reaches ~1.6V. Once this Soldering the Exposed Pad to the GND plane (DFN version) OUT is recommended to improve thermal performance. 3531fb 10

LTC3531/ LTC3531-3.3/LTC3531-3 APPLICATIOUS IUFORWATIOU Component Selection ductor value with a >500mA current rating and <400mΩ DCR is recommended. For applications where radiated Only three power components are required to noise is a concern, a toroidal or shielded inductor can be complete the design of the buck-boost converter, V OUT used. Table 2 contains a list of inductor manufacturers. programming resistors are needed for the adjustable version. The high operating frequency and low peak Capacitor Selection currents of the LTC3531 allow the use of low value, low The buck-boost convertor requires two capacitors. Ceramic profi le inductors and tiny external ceramic capacitors. X5R types will minimize ESL and ESR while maintaining capacitance at rated voltage over temperature. The V Inductor Selection IN capacitor should be at least 2.2μF. The V capacitor OUT For best effi ciency, choose an inductor with high frequency should be between 4.7μF and 22μF. A larger output capaci- core material, such as ferrite, to reduce core loses. The tor should be used if lower peak to peak output voltage inductor should have low DCR (DC resistance) to reduce ripple is desired. A larger output capacitor will also improve the I2R losses, and must be able to handle the peak load regulation on V . See Table 3 for a list of capacitor OUT inductor current without saturating. A 10μH to 22μH in- manufacturers for input and output capacitor selection. Table 2. Inductor Vendor Information Table 3. Capacitor Vendor Information Supplier Series Phone Website Supplier Series Phone Website COEV DN4835 (800) 227-7040 www.coev.net AVX X5R (803) 448-9411 www.avxcorp.com Coilcraft MSS4020 (847) 639-6400 www.coilcraft.com Murata X5R USA: (814) 237-1431 www.murata.com LPO3310 (800) 831-9172 DS1608 Sanyo POSCAP (619) 661-6322 www.sanyovideo.com Murata LQH43CN USA: (814) 237-1431 www.murata.com Taiyo Yuden X5R (408) 573-4150 www.taiyo-yuden.com LQH32CN (800) 831-9172 TDK X5R (847) 803-6100 www.component.tdk.com Sumida CDRH4D18 USA: (847) 956-0666 www.sumida.com CDRH3D16/HP Japan: 81-3-3607-5111 Toko D312C (847) 297-0070 www.tokoam.com D412C DB320C 3531fb 11

LTC3531/ LTC3531-3.3/LTC3531-3 APPLICATIOUS IUFORWATIOU SHUTDOWN COUT CIN VIN VOUT L GND 4 – SHDN VOUT – 3 GND 5 – VIN GND – 2 6 – SW1 SW2 – 1 SOT PIN-OUT Recommended Layout (SOT Versions) 3531fb 12

LTC3531/ LTC3531-3.3/LTC3531-3 TYPICAL APPLICATIOU 5V/Li-Ion to 3.3V with ThinSOT (3.3V Version) 95 100 10μH 4.4VIN 90 5VIN SW1 SW2 VIN VOUT P 3.1V TO VIN VOUT 3.3V %) 85 10 OW 5V LTC3531-3.3 160mA Y ( 3.6VIN ER 5V/Li-Ion +– 2.2μF 10μF CIENC 80 3.1VIN LOSS SHDN GND EFFI 75 1 (mW ) 3531 TA02a POWER LOSS AT 3.6VIN 70 ON OFF 65 0.1 0.1 1 10 100 1000 LOAD CURRENT (mA) 3531 TA02b 2 AA Alkaline to 3V with ThinSOT (3V Version) 90 100 10μH 85 SW1 SW2 A1L.8K2VA3 V.LxT2II OVNANAE ++–– 2.2μF VSIHLNTDCN3531VG-ON3UDT V381V0O0mμUTFA EFFICIENCY (%) 787005 2.5VIN 3.2VIN 1.8VIN 110 POWER LOSS (mW ) POWER LOSS AT 3.2VIN 3531 TA03a 65 ON OFF 60 0.1 0.1 1 10 100 1000 LOAD CURRENT (mA) 3531 TA03b USB to 5V with 3 × 3 DFN (Adjustable Version) 95 100 10μH 90 EFFICIENCY SW1 SW2 4.35VU STOB VIN VOUT V5VOUT %) 85 10 POW 5.25V 4.7μF LTC3531 R1M2 200mA NCY ( 80 ER LO 2.2μF FB 10μF CIE SS 1Ω SHDN GND R3214k EFFI 75 POWER LOSS 1 (mW ) 3531 TA04a 70 ON OFF 65 0.1 0.1 1 10 100 1000 LOAD CURRENT (mA) 3531 TA04b 3531fb 13

LTC3531/ LTC3531-3.3/LTC3531-3 PACKAGE DESCRIPTIOU S6 Package 6-Lead Plastic TSOT-23 (Reference LTC DWG # 05-08-1636) 2.90 BSC 0.62 0.95 (NOTE 4) MAX REF 1.22 REF 1.50 – 1.75 3.85 MAX 2.62 REF 1.4 MIN 2.80 BSC (NOTE 4) PIN ONE ID RECOMMENDED SOLDER PAD LAYOUT 0.30 – 0.45 0.95 BSC PER IPC CALCULATOR 6 PLCS (NOTE 3) 0.80 – 0.90 0.20 BSC 0.01 – 0.10 1.00 MAX DATUM ‘A’ 0.30 – 0.50 REF 1.90 BSC 0.09 – 0.20 (NOTE 3) S6 TSOT-23 0302 NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 2. DRAWING NOT TO SCALE 5. MOLD FLASH SHALL NOT EXCEED 0.254mm 3. DIMENSIONS ARE INCLUSIVE OF PLATING 6. JEDEC PACKAGE REFERENCE IS MO-193 3531fb 14

LTC3531/ LTC3531-3.3/LTC3531-3 PACKAGE DESCRIPTIOU DD Package 8-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1698) 0.675 ±0.05 3.5 ±0.05 1.65 ±0.05 2.15 ±0.05 (2 SIDES) PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 2.38 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS R = 0.115 0.38 ± 0.10 TYP 5 8 3.00 ±0.10 1.65 ± 0.10 (4 SIDES) (2 SIDES) PIN 1 TOP MARK (NOTE 6) (DD) DFN 1203 4 1 0.200 REF 0.75 ±0.05 0.25 ± 0.05 0.50 BSC 2.38 ±0.10 (2 SIDES) 0.00 – 0.05 BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1) 2.DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6.SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON TOP AND BOTTOM OF PACKAGE 3531fb 15 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.

LTC3531/ LTC3531-3.3/LTC3531-3 TYPICAL APPLICATIOU Complete USB/Li-Ion Powered System with 3.3V and Linear Charger OUT 5V (NOM) LTC4055 VOUT: USB OR BATTERY OTHER FROM USB IN1 OUT DC/DC CABLE L1 IN2 CHRG 10μH HPWR ACPR SUSPEND USB POWER SUSP VNTC 3.1V TO 5.25V SW1 SW2 VOUT + BAT TIMER VIN VOUT 31.630VmA –Li-Ion CLPROG LTC3531-3.3 C1 C2 GND PROG 100k 22μF SHDN 10μF SHDNWALLNTC 100k 0.1μF GND 3531 TA05 C1, C2: TAIYO YUDEN JMK316BJ106ML L1: MURATA LQH43CN100K03 (650mA 0.24Ω) RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1930/LT1930A 1A (I ), 1.2MHz/2.2MHz, High Effi ciency Step-Up DC/DC Converter V : 2.6V to 16V, V = 34V, SW IN OUT(MAX) I = 4.2mA/5.5mA, I < 1μA, ThinSOT Package Q SD LTC3400/LTC3400B 600mA (I ), 1.2MHz Synchronous Step-Up DC/DC Converter V : 0.85V to 5V, V = 5V, SW IN OUT(MAX) I = 19μA/300μA, I < 1μA, ThinSOT Package Q SD LTC3401/LTC3402 1A/2A (I ), 3MHz Synchronous Step-Up DC/DC Converter V : 0.5V to 5V, V = 6V, I = 38μA, SW IN OUT(MAX) Q I < 1μA, MS Package SD LTC3405/LTC3405A 300mA (I ), 1.5MHz Synchronous Step-Down DC/DC Converter V : 2.7V to 6V, V = 0.8V, I = 20μA, OUT IN OUT(MIN) Q I ≤ 1μA, MS10 Package SD LTC3406/LTC3406B 600mA (I ), 1.5MHz Synchronous Step-Down DC/DC Converter V : 2.5V to 5.5V, V = 0.6V, I = 20μA, OUT IN OUT(MIN) Q I ≤ 1μA, ThinSOT Package SD LTC3421 3A (I ), 3MHz Synchronous Step-Up DC/DC Converter V : 0.5V to 4.5V, V = 5.25V, I = 12μA, SW IN OUT(MAX) Q I < 1μA, QFN Package SD LTC3422 1.5A (I ), 3MHz Synchronous Step-Up DC/DC Converter V : 0.5V to 4.5V, V = 5.25V, I = 25μA, SW IN OUT(MAX) Q ISD < 1μA, 3mm × 3mm DFN Package LTC3426 2A (I ), 1.2MHz Step-Up DC/DC Converter in SOT-23 V : 1.6V to 5V, V up to 5.5V SW IN OUT LTC3428 4A (I ), 1.2MHz Step-Up DC/DC Converter V : 1.6V to 5V, V up to 5.5V SW IN OUT LTC3429 600mA (I ), 500kHz Synchronous Step-Up DC/DC Converter V : 0.5V to 4.4V, V = 5V, I = 20μA, SW IN OUT(MIN) Q I < 1μA, QFN Package SD LTC3440 600mA (I ), 2MHz Synchronous Buck-Boost DC/DC Converter V : 2.5V to 5.5V, V = 5.5V, I = 25μA, OUT IN OUT(MIN) Q I < 1μA, MS, DFN Packages SD LTC3441 600mA (I ), 2MHz Synchronous Buck-Boost DC/DC Converter V : 2.5V to 5.5V, V = 5.5V, I = 25μA, OUT IN OUT(MIN) Q I < 1μA, DFN Package SD LTC3442 2MHz Synchronous Buck-Boost with Auto-Burst V : 2.4V to 5.5V, V up to 5.25V IN OUT LTC3443 1.2A (I ), 600kHz Synchronous Buck-Boost DC/DC Converter V : 2.4V to 5.5V, V = 5.25V, I = 28μA, OUT IN OUT(MIN) Q I < 1μA, MS Package SD LTC3458 1.4A, 1.5MHz Synchronous Step-Up DC/DC Converter V : 1.5V to 6V, V up to 7.5V IN OUT LTC3458L 1.7A, 1.5MHz Synchronous Step-Up DC/DC Converter V : 1.5V to 6V, V up to 6V IN OUT LTC3459 10V Micropower Synchronous Step-Up DC/DC Converter V : 1.5V to 5.5V, V up to 10V IN OUT LTC3525/LTC3525-3.3/ 400mA (I ), Synchronous Step-Up DC/DC Converter V : 0.5V to 4.5V, I = 7μA, I < 1μA, SW IN Q SD LTC3525-5 with Output Disconnect 2mm × 2mm SC70 Package 3531fb 16 Linear Technology Corporation LT 0807 REV B • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2006