LTC3531/ LTC3531-3.3/LTC3531-3 200mA Buck-Boost Synchronous DC/DC Converters U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO Regulated Output with Input Above, Below or Equal to the Output Single Inductor Up to 90% Efficiency VIN Range: 1.8V to 5.5V 200mA at 3.3VOUT from 3.6V Input 125mA at 3VOUT from 2.5V Input Fixed VOUT Versions (TSOT, DFN): 3.3V, 3V Adjustable VOUT Version (DFN): 2V to 5V Burst Mode® Operation, No External Compensation Ultra Low Quiescent Current: 16μA, Shutdown Current <1μA Only 3 External Components Required (Fixed Voltage Versions) Short-Circuit Protection Output Disconnect in Shutdown Available in 6-Pin ThinSOT and 3mm × 3mm DFN Packages U APPLICATIO S ■ ■ ■ The devices include two 0.5Ω N-channel MOSFET switches and two P-channel switches (0.5Ω, 0.8Ω). Quiescent current is typically 16μA, making the parts ideal for battery power applications. Other features include a <1μA shutdown current, current limiting, thermal shutdown and output disconnect. The parts are offered in a 6-pin ThinSOTTM package for fixed voltage versions or a 3mm × 3mm DFN package for fixed and adjustable versions. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents including 6166527. Handheld Instruments MP3 Players Handheld computers PDA/GPS U ■ The LTC®3531/LTC3531-3.3/LTC3531-3 are synchronous buck-boost DC/DC converters that operate from input voltages above, below or equal to the output voltage. The topology incorporated in the ICs provides a continuous transfer through all operating modes, making the product ideal for single cell Li-Ion and multicell alkaline or nickel applications. The converters operate in Burst Mode, minimizing solution footprint and component count as well as providing high conversion efficiency over a wide range of load currents. TYPICAL APPLICATIO Efficiency vs VIN 100 10μH 95 Li-Ion VIN + SW2 VOUT LTC3531-3.3 2.2μF VOUT 3.3V 160mA 10μF SHDN EFFICIENCY (%) 90 SW1 VIN 3.1V TO 4.2V BOOST MODE 85 BUCK MODE 80 4SW MODE 75 GND 70 3531 TA01a 65 ON OFF 60 1.5 3.3VOUT AT 100mA 2 2.5 3 3.5 4 4.5 INPUT VOLTAGE (V) 5 5.5 3531 TA01b 3531fb 1 LTC3531/ LTC3531-3.3/LTC3531-3 W W U W ABSOLUTE AXI U RATI GS (Note 1) VIN, VOUT, SW1, SW2, SHDN Voltage ...........–0.3 to 6V SW1, SW2 Voltage, <100ns Pulse ..................–0.3 to 7V Operating Temperature Range (Notes 2, 3) –40°C to 85°C Storage Temperature Range................... –65°C to 125°C Lead Temperature (TS6, Soldering, 10 sec) .......... 300°C U W U PACKAGE/ORDER I FOR ATIO TOP VIEW TOP VIEW SW2 1 GND, PGND 2 VOUT 3 6 SW1 5 VIN 4 SHDN PGND 7 SW2 9 3 6 VOUT SHDN 4 5 FB* DD PACKAGE 8-LEAD (3mm × 3mm) PLASTIC DFN 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. TJMAX = 125°C, θJA = 102°C/W LTC3531ES6-3.3 LTC3531ES6-3 8 VIN 2 GND S6 PACKAGE 6-LEAD PLASTIC TSOT-23 ORDER PART NUMBER SW1 1 S6 PART MARKING ORDER PART NUMBER LTBWM LTCBK DD PART MARKING LTC3531EDD LTC3531EDD-3.3 LTC3531EDD-3 LBVC LBWH 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 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 = 3.6V VOUT = 3.3V unless otherwise noted. PARAMETER VIN Minimum Startup Voltage VOUT Regulation Output Voltage (3.3V Version) Output Voltage (3V Version) FB Voltage (Adj Version) FB Input Current (Adj Version) Operating Current Quiescent Current in Sleep: Shutdown Current Switch Performance NMOS Switch Leakage PMOS Switch Leakage NMOS B, C RDSON PMOS A RDSON CONDITIONS MIN TYP MAX 1.65 1.8 V 3.32 3.02 1.225 1 3.39 3.09 1.25 50 V V V nA VIN = 5V, VOUT = 3.6V, FB = 1.3V VOUT = 3.6V SHDN = 0V, VOUT = 0V 16 6 30 10 1 μA μA μA Switches B and C Switches A and D VIN = 5V VIN = 5V 0.2 0.2 0.5 0.5 2 2 μA μA Ω Ω ● No Load No Load No Load VFB = 1.225V VIN VOUT VIN ● ● ● 3.25 2.95 1.20 UNITS 3531fb 2 LTC3531/ LTC3531-3.3/LTC3531-3 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 3.6V VOUT = 3.3V unless otherwise noted. PARAMETER PMOS D RDSON (3.3V Version or Adjustable Version set to 3.3V) PMOS D RDSON (3V Version) Peak Current Limit CONDITIONS VOUT = 3.1V VOUT = 2.8V L = 10μH, VIN = 5V SHDN SHDN Input Threshold SHDN Hysteresis SHDN Leakage Current MIN 295 0.4 VSHDN U W TYPICAL PERFOR A CE CHARACTERISTICS 300 450 L = 10μH VOUT = 3.3V IPEAK, IVALLEY, IZERO vs VIN CURRENT (mA) MAXIMUM IOUT (mA) 150 100 2 2.5 3 3.5 4 4.5 5 14 250 200 IVALLEY 150 2 2.5 3 0 3.5 4 4.5 5.5 80 2.5 100 80 60 40 5 5.5 VIN (V) 3531 G04 5 5.5 3.35 70 60 50 22μF 40 3.30 22μF 3.25 47μF 30 3.20 50mA LOAD 0 4.5 4.5 10μF 10μF 10 4 3.5 4 VIN (V) 3.40 20 20 3 Load Regulation vs COUT (3.3V Version) VOUT (V) VRIPPLE PEAK-PEAK (mV) 140 3.5 2 3531 G03 100 90 3 1.5 VOUT Ripple vs COUT (3.3V Version) 120 IIN (mA) 5 3531 G02 160 2.5 IVOUT VIN (V) IIN Short Circuit vs VIN 2 8 2 IZERO 3531 G01 0 1.5 10 6 VIN (V) 180 12 4 0 1.5 5.5 IVIN 16 300 50 0 1.5 1 18 IPEAK 100 50 V mV μA Sleep Currents L = 10μH 350 200 1.4 460 20 400 250 1 60 0.01 UNITS Ω Ω mA TA = 25°C unless otherwise specified. CURRENT (μA) 350 MAX Continuous operation above the specified maximum operating junction temperature may result in device degradation or failure. Note 3: The LTC3531 is guaranteed to meet performance specifications from 0°C to 70°C. Specifications over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed 125°C when overtemperature protection is active. Maximum IOUT vs VIN (3.3V Version) TYP 0.8 0.9 365 1.5 2 2.5 3 3.5 4 VIN (V) 4.5 5 5.5 3531 G05 VIN = 3.6V 3.15 1 0.1 10 100 LOAD CURRENT (mA) 1000 3521 G06 3531fb 3 LTC3531/ LTC3531-3.3/LTC3531-3 U W TYPICAL PERFOR A CE CHARACTERISTICS Start-Up into Resistive Load L = 10μH TA = 25°C unless otherwise specified. Burst Frequency vs Load (3.3V Version) 30 1000 28 VOUT Regulation vs Temperature (3.3V Version) 3.350 L = 10μH COUT = 10μF VIN = 3.6V ILOAD = 10mA 26 100 RMIN (Ω) 22 20 18 16 3.325 50mA 10mA 10 VOUT (V) FREQUENCY (kHz) 24 5mA 1mA 3.275 1 14 3.300 0.5mA 12 10 1.5 2 2.5 3 3.5 4 VIN (V) 4.5 5 0.1 1.5 5.5 2 3 2.5 3.5 4 VIN (V) 4.5 5 Switch On Resistances VIN = 5V VOUT = 3.3V 3.250 –40 –20 60 0 20 40 TEMPERATURE (°C) 80 3531 G08 3531 G07 1000 5.5 3531 G09 SHDN Pin Threshold and Hysteresis IPEAK, IVALLEY vs Temperature 1 400 D (PMOS) 100 IPEAK 350 900 0.9 700 A (PMOS) 600 250 IVALLEY 200 150 2.5VIN 3.3VOUT 10μH 100 500 400 –40 B,C (NMOS) –20 60 0 20 40 TEMPERATURE (°C) 50 80 100 3531 G10 VOLTAGE (V) 800 CURRENT (mA) RDSON (mΩ) 300 0 –40 0.8 OPERATING 0.7 SHUTDOWN 0.6 IZERO –20 0 40 60 20 TEMPERATURE (°C) 80 100 3531 G11 0.5 – 40 – 20 60 0 20 40 TEMPERATURE (°C) 80 100 3531 G12 3531fb 4 LTC3531/ LTC3531-3.3/LTC3531-3 U W TYPICAL PERFOR A CE CHARACTERISTICS Buck Mode at 5VIN, 3.3VOUT 200mA TA = 25°C unless otherwise specified. Buck Mode at 5VIN, 3.3VOUT 100mA SW1 5V/DIV SW2 5V/DIV VOUT (AC) 50mV/DIV IL 200mA/DIV SW1 5V/DIV SW2 5V/DIV VOUT (AC) 50mV/DIV IL 200mA/DIV L = 10μH COUT = 22μF 5μs/DIV 3531 G13 L = 10μH COUT = 22μF 5μs/DIV 3531 G14 4 Switch Mode Waveforms at 3.6VIN, 3.3VOUT 200mA Buck Mode Waveforms at 5VIN, 3.3VOUT 20mA SW1 5V/DIV SW2 5V/DIV VOUT (AC) 50mV/DIV IL 200mA/DIV SW1 5V/DIV SW2 5V/DIV VOUT (AC) 50mV/DIV IL 200mA/DIV L = 10μH COUT = 22μF 5μs/DIV 3531 G15 L = 10μH COUT = 22μF 4 Switch Mode Waveforms at 3.6VIN, 3.3VOUT 100mA 5μs/DIV 3531 G16 4 Switch Mode Waveforms at 3.6VIN, 3.3VOUT 20mA SW1 5V/DIV SW2 5V/DIV VOUT (AC) 50mV/DIV IL 200mA/DIV SW1 5V/DIV SW2 5V/DIV VOUT (AC) 50mV/DIV IL 200mA/DIV L = 10μH COUT = 22μF 5μs/DIV 3531 G17 SW1 SW2 VOUT (AC) IL L = 10μH COUT = 22μF 5μs/DIV 3531 G18 3531fb 5 LTC3531/ LTC3531-3.3/LTC3531-3 U W TYPICAL PERFOR A CE CHARACTERISTICS TA = 25°C unless otherwise specified. Boost Mode Waveforms at 2.5VIN, 3.3VOUT 100mA Boost Mode Waveforms at 2.5VIN, 3.3VOUT 20mA SW1 5V/DIV SW2 5V/DIV VOUT (AC) 50mV/DIV IL 200mA/DIV SW1 5V/DIV SW2 5V/DIV VOUT (AC) 50mV/DIV IL 200mA/DIV L = 10μH COUT = 22μF 3531 G19 5μs/DIV L = 10μH COUT = 22μF SW1 5V/DIV SW2 5V/DIV VOUT (AC) 50mV/DIV IL 200mA/DIV 200mA/DIV VOUT 1V/DIV IL 200mA/DIV 3531 G21 1μs/DIV 25μs/DIV 3.6VIN, 3.3VOUT Load Step 200mA to 80mA 3531 G22 SW1 and SW2 Close-Up in Four Switch Mode 100mA LOAD 20mA LOAD 3531 G20 Start-Up into 50mA Load at 3.3 VOUT (Shows Start, Buck, Then 4sw Modes) Shorted Output L = 10μH COUT = 22μF VIN = 5 5μs/DIV 20mA LOAD VOUT (AC) 20mV/DIV SW1 2V/DIV IL 200mA/DIV SW2 2V/DIV COUT = 22μF 25μs/DIV 3531 G23 VIN = 3.6V VOUT = 3.3V 200ns/DIV 3531 G24 3531fb 6 LTC3531/ LTC3531-3.3/LTC3531-3 U U U PI FU CTIO S ThinSOT/DFN Packages SW2 (Pin 1/Pin 7): Buck-Boost Switch Pin Where Internal Switches C and D are Connected. An optional Schottky diode can be connected from SW2 to VOUT for a moderate efficiency improvement. Minimize trace length to keep EMI down. GND (Pin 2/Pin 3): Signal Ground for the IC. PGND (Pin 2/Pin 8): Power Ground for the IC. (Shared on ThinSOT version) VOUT (Pin 3/Pin 6): Output of the Buck-Boost Synchronous Rectifier. A filter capacitor is placed from VOUT to GND. A ceramic bypass capacitor is recommended as close to the VOUT and GND pins as possible. SHDN (Pin 4/Pin 4): External Shutdown Pin. An applied voltage of < 0.4V shuts down the converter. A voltage above >1.4V will enable the converter. VIN (Pin 5/Pin 2): Input Supply Pin for the Buck-Boost Converter. A minimum 2.2μF Ceramic Capacitor should be placed between VIN and GND. FB (NA/Pin 5): Feedback Pin for the Adjustable Version. Connect the resistor divider tap here. The output voltage can be adjusted from 2V to 5V. ⎛ R2 ⎞ VOUT = 1 . 225⎜ 1+ ⎟ ⎝ R1 ⎠ SW1 (Pin 6/Pin 1): Buck-Boost Switch Pin Where Internal Switches A and B are Connected. Connect the inductor from SW1 to SW2. Exposed Pad (Pin 9, DFN): Solder to PCB ground for optimal thermal performance. 3531fb 7 LTC3531/ LTC3531-3.3/LTC3531-3 W BLOCK DIAGRA SW1 SW2 SW A SW D VIN VOUT GATE DRIVERS AND ANTICROSS CONDUCTION SW B 365mA SW C VBEST PEAK CURRENT LIMIT BUCK, 4SW, BOOST VIN VBEST AND MODE DETECT STATE MACHINE AND LOGIC VIN IZERO/IVALLEY DETECT VOUT 1.225V VREF UVLO R2 1.65V VOUT COMPARATOR SHDN SHUTDOWN THERMAL SHUTDOWN PGND GND COMBINED FOR TSOT FB NOT BONDED FOR 3.3V AND 3V VERSIONS R1 INTERNAL R1 AND R2 DISABLED FOR ADJ VERSION 3531 BD 3531fb 8 LTC3531/ LTC3531-3.3/LTC3531-3 U OPERATIO The LTC3531, LTC3531-3.3 and LTC3531-3 synchronous buck-boost converters utilize a Burst Mode control technique to achieve high efficiency over a wide dynamic range of load currents. A 2% accurate comparator is used to monitor the output voltage. If VOUT is above its programmed reference threshold no switching occurs and only quiescent current is drawn from the power source (sleep mode). When VOUT drops below the reference threshold the IC “wakes up”, switching commences, and the output capacitor is charged. The value of the output capacitor, the load current, and the comparator hysteresis (~1%) determines the number of current pulses required to pump-up the output capacitor before the part returns to sleep. In order to determine the best operating mode for the converter, the LTC3531 contains a second comparator that monitors the relative voltage difference between VIN and VOUT. Input and output voltages in the various modes as well as typical inductor currents are shown in Figure 1. Regions of the current waveforms where switches A and D are on provide the highest efficiency since energy is transferred directly from the input source to the output. Boost Mode If VIN is ~400mV below VOUT, the LTC3531 operates in boost or step-up mode. Referring to Figure 1 (left side) when VOUT falls below its regulation voltage, switches A and C are turned on (VIN is applied across the inductor) and current is ramped until IPEAK is detected. When this VIN occurs, C is turned off, D is turned on and current is delivered to the output capacitor (VIN – VOUT is applied across the inductor). Inductor current falls when D is on, until an IVALLEY is detected. Terminating at IVALLEY, rather than IZERO, results in an increased load current capability for a given peak current. This AC then AD switch sequence is repeated until the output is pumped above its regulation voltage, a final IZERO is detected, and the part returns to sleep mode (IVALLEY is ignored and IZERO is used in all modes once VOUT is above its programmed value). 4-Switch Mode If (VOUT – 400mV) < ~VIN < (VOUT + 800mV), the LTC3531 operates in 4-switch step-up/down mode. Returning to Figure 1 (center) when VOUT falls below its regulation voltage, switches A and C are turned on and current is ramped until IPEAK is detected. As with Boost Mode operation, C is then turned off, D is turned on and current is delivered to the output. When A and D are on, the inductor current slope is dependant on the relationship between VIN, VOUT, and the RDSON of the switches. In 4-switch mode, a tOFF timer (approximately 3μs) is used to terminate the AD pulse. Once the tOFF timer expires, switch A is turned off, B is turned on and inductor current is ramped down (VOUT is applied across the inductor) until IVALLEY is detected. This sequence is repeated until the output is regulated, BD switches are turned on, and a final IZERO is detected. Anticross conduction circuitry in all modes ensures the P-channel MOSFET and N-channel MOSFET switch pairs (A and B or D and C) are never turned on simultaneously. VOUT VIN VOUT A D VIN L SW1 SW2 IMAX B C IPEAK tOFF tOFF tOFF IVALLEY IZERO AC AD AC AD BOOST MODE AC AD BD AC AD BD AC 4SW MODE AD BD AD BD AD BD BUCK MODE 3531 F01 Figure 1. Voltage and Current Waveforms 3531fb 9 LTC3531/ LTC3531-3.3/LTC3531-3 U OPERATIO Buck Mode If VIN is ~800mV above VOUT, the LTC3531 operates in buck or step-down mode. The higher offset between VIN and VOUT (800mV) is required to ensure sufficient magnetizing voltage across the inductor when the RDSONS are taken into account. At the beginning of a buck mode cycle (Figure 1 right side) switches A and D are turned on (VIN – VOUT is applied across the inductor), current is delivered to the output and ramped up until IPEAK is detected. When this occurs, A is turned off, B is turned on and inductor current falls (–VOUT across the inductor) until an IVALLEY is detected. This AD then BD switch sequence is repeated until the output is pumped above its regulation voltage, a final IZERO is detected, and the part returns to sleep mode. Start-Up Mode Before VOUT reaches approximately 1.6V, the D switch is disabled and its body diode is used to transfer current to the output capacitor. In start-up mode, the IVALLEY/IZERO sense circuit is disabled and an alternate algorithm is used to control inductor current. When the LTC3531 is brought out of shutdown (assuming VOUT is discharged) switches A and C are turned on until the inductor current reaches IPEAK. The AC switches are then turned off and inductor current flows to the output through the B switch and D body diode. The period for the B switch/D body diode is controlled by the tOFF timer to ~800nS. This sequence of AC switch-on to IPEAK then B switch and D body diode for ~800ns is repeated until VOUT reaches ~1.6V. Once this threshold is reached, the LTC3531 will transfer through the required modes until VOUT is brought into regulation. Due to propagation delays in the sense circuitry, the magnitudes of the IPEAK, IVALLEY, and IZERO currents may shift depending on VIN, VOUT and operating mode. OTHER LTC3531 FEATURES Shutdown: The part is shut down by pulling SHDN below 0.4V, and made active by pulling the pin up to VIN or VOUT. Note that SHDN an be driven above VIN or VOUT, as long as it is limited to less than 6V. Output Disconnect and Inrush Limiting: The LTC3531 is designed to allow true output disconnect by opening both P-channel MOSFET rectifiers. This allows VOUT to go to zero volts during shutdown, drawing no current from the input source. It also provides inrush current limiting at turn-on, minimizing surge currents seen by the input supply. Thermal Shutdown: If the die temperature reaches approximately 150°C, the part will go into thermal shutdown and all switches will be turned off. The part will be enabled again when the die temperature has dropped by 10°C (nominal). To deliver the power that the LTC3531 is capable of, it is imperative that a good thermal path be provided to dissipate the heat generated within the package. It is recommended that multiple vias in the printed circuit board be used to conduct heat away from the IC and into a copper plane with as much area as possible. Soldering the Exposed Pad to the GND plane (DFN version) is recommended to improve thermal performance. 3531fb 10 LTC3531/ LTC3531-3.3/LTC3531-3 U W U U APPLICATIO S I FOR ATIO Component Selection Only three power components are required to complete the design of the buck-boost converter, VOUT programming resistors are needed for the adjustable version. The high operating frequency and low peak currents of the LTC3531 allow the use of low value, low profile inductors and tiny external ceramic capacitors. ductor value with a >500mA current rating and <400mΩ DCR is recommended. For applications where radiated noise is a concern, a toroidal or shielded inductor can be used. Table 2 contains a list of inductor manufacturers. Capacitor Selection For best efficiency, choose an inductor with high frequency core material, such as ferrite, to reduce core loses. The inductor should have low DCR (DC resistance) to reduce the I2R losses, and must be able to handle the peak inductor current without saturating. A 10μH to 22μH in- The buck-boost convertor requires two capacitors. Ceramic X5R types will minimize ESL and ESR while maintaining capacitance at rated voltage over temperature. The VIN capacitor should be at least 2.2μF. The VOUT capacitor should be between 4.7μF and 22μF. A larger output capacitor should be used if lower peak to peak output voltage ripple is desired. A larger output capacitor will also improve load regulation on VOUT. See Table 3 for a list of capacitor manufacturers for input and output capacitor selection. Table 2. Inductor Vendor Information Table 3. Capacitor Vendor Information Inductor Selection Supplier COEV Coilcraft Murata Sumida Toko Series DN4835 MSS4020 LPO3310 DS1608 LQH43CN LQH32CN CDRH4D18 CDRH3D16/HP D312C D412C DB320C Phone (800) 227-7040 (847) 639-6400 Website www.coev.net www.coilcraft.com USA: (814) 237-1431 www.murata.com (800) 831-9172 USA: (847) 956-0666 www.sumida.com Japan: 81-3-3607-5111 (847) 297-0070 www.tokoam.com Supplier AVX Murata Series X5R X5R Phone (803) 448-9411 USA: (814) 237-1431 (800) 831-9172 Sanyo POSCAP (619) 661-6322 Taiyo Yuden X5R (408) 573-4150 TDK X5R (847) 803-6100 Website www.avxcorp.com www.murata.com www.sanyovideo.com www.taiyo-yuden.com www.component.tdk.com 3531fb 11 LTC3531/ LTC3531-3.3/LTC3531-3 U W U U APPLICATIO S I FOR ATIO SHUTDOWN COUT VIN CIN VOUT L GND VOUT – 3 4 – SHDN 5 – VIN GND – 2 6 – SW1 SW2 – 1 SOT PIN-OUT GND Recommended Layout (SOT Versions) 3531fb 12 LTC3531/ LTC3531-3.3/LTC3531-3 U TYPICAL APPLICATIO 5V/Li-Ion to 3.3V with ThinSOT (3.3V Version) 95 100 4.4VIN 10μH 5VIN 5V/Li-Ion VIN VOUT VOUT 3.3V 160mA LTC3531-3.3 + – 2.2μF 10μF SHDN GND 10 85 3.6VIN 80 3.1VIN 1 75 3531 TA02a POWER LOSS (mW) VIN 3.1V TO 5V SW2 EFFICIENCY (%) 90 SW1 POWER LOSS AT 3.6VIN 70 ON OFF 65 0.1 1 10 100 LOAD CURRENT (mA) 0.1 1000 3531 TA02b 2 AA Alkaline to 3V with ThinSOT (3V Version) 90 100 10μH 2 x AA ALKALINE + – SW1 SW2 VIN VOUT VOUT 3V 80mA LTC3531-3 2.2μF + – 10μF SHDN GND 80 10 2.5VIN 3.2VIN 75 1.8VIN 70 1 POWER LOSS (mW) VIN 1.8V TO 3.2V EFFICIENCY (%) 85 POWER LOSS AT 3.2VIN 3531 TA03a 65 ON OFF 60 0.1 1 10 100 LOAD CURRENT (mA) 0.1 1000 3531 TA03b USB to 5V with 3 × 3 DFN (Adjustable Version) 95 100 10μH 4.7μF SW1 SW2 VIN VOUT LTC3531 2.2μF 1Ω R2 1M 10μF FB SHDN GND VOUT 5V 200mA R1 324k 3531 TA04a EFFICIENCY 10 85 80 POWER LOSS 1 75 POWER LOSS (mW) USB 4.35V TO 5.25V EFFICIENCY (%) 90 70 ON OFF 65 0.1 1 10 100 LOAD CURRENT (mA) 0.1 1000 3531 TA04b 3531fb 13 LTC3531/ LTC3531-3.3/LTC3531-3 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 1.4 MIN 3.85 MAX 2.62 REF 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) NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3. DIMENSIONS ARE INCLUSIVE OF PLATING 1.90 BSC S6 TSOT-23 0302 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 3531fb 14 LTC3531/ LTC3531-3.3/LTC3531-3 U PACKAGE DESCRIPTIO 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 TYP 5 3.00 ±0.10 (4 SIDES) 0.38 ± 0.10 8 1.65 ± 0.10 (2 SIDES) PIN 1 TOP MARK (NOTE 6) (DD) DFN 1203 0.200 REF 0.75 ±0.05 0.00 – 0.05 4 0.25 ± 0.05 1 0.50 BSC 2.38 ±0.10 (2 SIDES) 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 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. 15 LTC3531/ LTC3531-3.3/LTC3531-3 U TYPICAL APPLICATIO Complete USB/Li-Ion Powered System with 3.3VOUT and Linear Charger 5V (NOM) FROM USB CABLE SUSPEND USB POWER + Li-Ion – LTC4055 IN1 OUT IN2 CHRG HPWR ACPR SUSP BAT VOUT: USB OR BATTERY OTHER DC/DC VNTC 3.1V TO 5.25V TIMER C1 22μF 100k PROG SHDN WALL NTC SW1 SW2 VIN VOUT VOUT 3.3V 160mA LTC3531-3.3 CLPROG GND L1 10μH 100k 0.1μF C2 10μF SHDN GND 3531 TA05 C1, C2: TAIYO YUDEN JMK316BJ106ML L1: MURATA LQH43CN100K03 (650mA 0.24Ω) RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1930/LT1930A 1A (ISW), 1.2MHz/2.2MHz, High Efficiency Step-Up DC/DC Converter VIN: 2.6V to 16V, VOUT(MAX) = 34V, IQ = 4.2mA/5.5mA, ISD < 1μA, ThinSOT Package LTC3400/LTC3400B 600mA (ISW), 1.2MHz Synchronous Step-Up DC/DC Converter VIN: 0.85V to 5V, VOUT(MAX) = 5V, IQ = 19μA/300μA, ISD < 1μA, ThinSOT Package LTC3401/LTC3402 1A/2A (ISW), 3MHz Synchronous Step-Up DC/DC Converter VIN: 0.5V to 5V, VOUT(MAX) = 6V, IQ = 38μA, ISD < 1μA, MS Package LTC3405/LTC3405A 300mA (IOUT), 1.5MHz Synchronous Step-Down DC/DC Converter VIN: 2.7V to 6V, VOUT(MIN) = 0.8V, IQ = 20μA, ISD ≤ 1μA, MS10 Package LTC3406/LTC3406B 600mA (IOUT), 1.5MHz Synchronous Step-Down DC/DC Converter VIN: 2.5V to 5.5V, VOUT(MIN) = 0.6V, IQ = 20μA, ISD ≤ 1μA, ThinSOT Package LTC3421 3A (ISW), 3MHz Synchronous Step-Up DC/DC Converter VIN: 0.5V to 4.5V, VOUT(MAX) = 5.25V, IQ = 12μA, ISD < 1μA, QFN Package LTC3422 1.5A (ISW), 3MHz Synchronous Step-Up DC/DC Converter VIN: 0.5V to 4.5V, VOUT(MAX) = 5.25V, IQ = 25μA, ISD < 1μA, 3mm × 3mm DFN Package LTC3426 LTC3428 LTC3429 2A (ISW), 1.2MHz Step-Up DC/DC Converter in SOT-23 4A (ISW), 1.2MHz Step-Up DC/DC Converter 600mA (ISW), 500kHz Synchronous Step-Up DC/DC Converter LTC3440 600mA (IOUT), 2MHz Synchronous Buck-Boost DC/DC Converter LTC3441 600mA (IOUT), 2MHz Synchronous Buck-Boost DC/DC Converter LTC3442 LTC3443 2MHz Synchronous Buck-Boost with Auto-Burst 1.2A (IOUT), 600kHz Synchronous Buck-Boost DC/DC Converter LTC3458 LTC3458L LTC3459 LTC3525/LTC3525-3.3/ LTC3525-5 1.4A, 1.5MHz Synchronous Step-Up DC/DC Converter 1.7A, 1.5MHz Synchronous Step-Up DC/DC Converter 10V Micropower Synchronous Step-Up DC/DC Converter 400mA (ISW), Synchronous Step-Up DC/DC Converter with Output Disconnect VIN: 1.6V to 5V, VOUT up to 5.5V VIN: 1.6V to 5V, VOUT up to 5.5V VIN: 0.5V to 4.4V, VOUT(MIN) = 5V, IQ = 20μA, ISD < 1μA, QFN Package VIN: 2.5V to 5.5V, VOUT(MIN) = 5.5V, IQ = 25μA, ISD < 1μA, MS, DFN Packages VIN: 2.5V to 5.5V, VOUT(MIN) = 5.5V, IQ = 25μA, ISD < 1μA, DFN Package VIN: 2.4V to 5.5V, VOUT up to 5.25V VIN: 2.4V to 5.5V, VOUT(MIN) = 5.25V, IQ = 28μA, ISD < 1μA, MS Package VIN: 1.5V to 6V, VOUT up to 7.5V VIN: 1.5V to 6V, VOUT up to 6V VIN: 1.5V to 5.5V, VOUT up to 10V VIN: 0.5V to 4.5V, IQ = 7μA, ISD < 1μA, 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