LTC3527/LTC3527-1 Dual 800mA/400mA, 1.2MHz/2.2MHz Synchronous Step-Up DC/DC Converters DESCRIPTION FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Dual Synchronous Step-Up DC/DC Converters Delivers 3.3V at 200mA/100mA from one Alkaline/ NiMH Cell, or 3.3V at 400mA/200mA from Two Cells VIN Start-Up Voltage: 700mV 0.5V to 5V VIN Range after Start-Up 1.6V to 5.25V VOUT Range Output Disconnect in Shutdown VIN > VOUT Operation 1.2MHz or 2.2MHz Operation Up to 94% Efficiency 12µA Quiescent Current in Burst Mode® Operation Inrush Current Limiting and Soft-Start Internal Synchronous Rectifiers Logic-Controlled Shutdown (< 2µA) Quick VOUT Discharge (LTC3527-1) 16-Lead, 0.75mm × 3mm × 3mm QFN Package The LTC®3527/LTC3527-1 are dual high efficiency, step-up DC/DC converters in a space saving 16-lead 3mm × 3mm QFN package. Battery life is maximized with a 700mV start-up voltage and operation down to 500mV once started. The ⎯S⎯H⎯D⎯N and PGOOD pins enable the converters to be sequenced or started together. The LTC3527/LTC3527-1 limit inrush current during startup. Selectable 1.2MHz or 2.2MHz operation provides a choice between the highest efficiency or smallest solution footprint. The current mode PWM design is internally compensated reducing external parts count. Burst Mode operation or fixed frequency operation is selectable via the MODE pin. Anti-ring circuitry reduces EMI in discontinuous mode. This device also features thermal shutdown. True output disconnect allows the output to be completely open in shutdown. The LTC3527-1 actively discharges VOUT1 or VOUT2 when its respective ⎯S⎯H⎯D⎯N goes low. Quiescent current in shutdown is less than 2µA. APPLICATIONS ■ ■ ■ ■ MP3/Personal Media Players Noise Canceling/Bluetooth Headsets Wireless Mice Portable Medical Instruments , LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION Two-Cell Alkaline to 3.3V/1.8V Synchronous Boost Converters VIN BURST 90 EFFICIENCY 4.7µF 4.7µH VIN1 VIN SW1 VOUT1 4.7µF SW2 VOUT2 619k FB1 ON 1M PGOOD1 MODE PGOOD2 1.21M 4.7µF SHDN2 GND 10 60 50 40 FIXED FREQUENCY 1 30 FSEL ON OFF VOUT 1.8V 150mA FB2 SHDN1 OFF 70 LTC3527 1.78M 100 80 4.7µH VIN2 POWER LOSS (mW) VOUT 3.3V 150mA 1000 100 1.6V to 3.2V EFFICIENCY (%) + 1.2MHz Efficiency and Power Loss POWER 20 LOSS 10 BURST 0 0.1 0.01 0.1 VIN = 2.4V VOUT1 = 3.3V 1 10 100 LOAD CURRENT (mA) 0.01 1000 35271 TA01b 35271 TA01 35271f 1 LTC3527/LTC3527-1 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) PGOOD2 GND PGOOD1 VIN TOP VIEW VIN, VIN1, VIN2 Voltage ................................. –0.3V to 6V SW1, SW2 Voltage (DC) .............................. –0.3V to 6V (Pulsed < 100ns) ..................................... –0.3V to 7V ⎯S⎯H⎯D⎯N⎯1, ⎯S⎯H⎯D⎯N⎯2, FB1, FB2 Voltage ............... –0.3V to 6V VOUT1, VOUT2 ................................................ –0.3V to 6V MODE, FSEL, PGOOD1, PGOOD2................. –0.3V to 6V Operating Temperature (Notes 2, 5) .........–40°C to 85°C Junction Temperature ........................................... 125°C Storage Temperature Range...................–65°C to 125°C 16 15 14 13 SHDN1 1 12 SHDN2 FB1 2 11 FB2 17 MODE 3 10 FSEL VIN1 4 6 7 8 VOUT1 SW1 SW2 VOUT2 9 5 VIN2 UD PACKAGE 16-LEAD (3mm × 3mm) PLASTIC QFN TJMAX = 125°C, θJA = 68°C/W EXPOSED PAD (PIN 17) IS PGND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3527EUD#PBF LTC3527EUD-1#PBF LTC3527EUD#TRPBF LTC3527EUD-1#TRPBF LDDK LCXP 16-Lead (3mm × 3mm) Plastic QFN 16-Lead (3mm × 3mm) Plastic QFN –40°C to 85°C –40°C to 85°C LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3527EUD LTC3527EUD-1 LTC3527EUD#TR LTC3527EUD-1#TR LDDK LCXP 16-Lead (3mm × 3mm) Plastic QFN 16-Lead (3mm × 3mm) Plastic QFN –40°C to 85°C –40°C to 85°C Consult LTC Marketing for parts specified with wider operating temperature ranges. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, –40°C to 85°C. VIN = 1.2V, VOUT1 = VOUT2 = 3.3V, TA = 25°C, unless otherwise noted. PARAMETER CONDITIONS Minimum Start-Up Voltage ILOAD = 1mA Output Voltage Adjust Range VOUT1 VOUT1, 0°C to 85°C VOUT2 VOUT2, 0°C to 85°C MIN ● ● ● Feedback Voltage FB1, FB2 TYP MAX UNITS 0.7 0.88 V 5.25 5.25 5.25 5.25 V V V V 1.7 1.6 1.7 1.6 1.20 1.224 V 1 50 nA V⎯S⎯H⎯D⎯N⎯1 = V⎯S⎯H⎯D⎯N⎯2 = 0V, Not Including Switch Leakage, VOUT1 = VOUT2 = 0V 0.1 2 µA Quiescent Current: Burst Mode Operation Measured on VOUT, VFB1 = VFB2 = 1.5V 12 Quiescent Current: Active VFB1 = VFB2 > 1.2V (Note 3) 500 900 µA NMOS Switch Leakage Current VSW1,2 = 5V, ⎯S⎯H⎯D⎯N⎯1,⎯2 = 0V 0.1 10 µA PMOS Switch Leakage Current VSW1,2 = 5V, VOUT1,2 = 0V, ⎯S⎯H⎯D⎯N⎯1,⎯2 = 0V 0.1 10 Feedback Input Current FB1, FB2 VFB1,2 = 1.20V Quiescent Current: Shutdown 1.176 µA µA 35271f 2 LTC3527/LTC3527-1 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, –40°C to 85°C. VIN = 1.2V, VOUT1 = VOUT2 = 3.3V, TA = 25°C, unless otherwise noted. PARAMETER CONDITIONS MIN NMOS Switch On-Resistance, SW1 TYP MAX UNITS 0.30 Ω NMOS Switch On-Resistance, SW2 0.50 Ω PMOS Switch On-Resistance, SW1 0.40 Ω PMOS Switch On-Resistance, SW2 0.60 Ω NMOS Current Limit, SW1 ● 800 mA NMOS Current Limit, SW2 ● 400 mA 85 Current Limit Delay to Output Time (Note 4) Maximum Duty Cycle VFB1,2 = 1V ● Minimum Duty Cycle VFB1,2 = 1.3V ● Switching Frequency VFSEL = 0V ● 0.9 1.2 1.5 MHz Switching Frequency VFSEL = 3.3V ● 1.9 2.2 2.8 MHz ⎯S⎯H⎯D⎯N⎯1,⎯2 Input High Voltage 60 ns 90 % 0 0.88 V ⎯S⎯H⎯D⎯N⎯1,⎯2 Input Low Voltage ⎯S⎯H⎯D⎯N⎯1,⎯2 Input Current V⎯S⎯H⎯D⎯N⎯1,⎯2 = 3.3V PGOOD1, PGOOD2 Threshold Referenced to the Feedback Voltage PGOOD1, PGOOD2 Low Voltage IPGOOD1,2 = 1mA PGOOD1, PGOOD2 Leakage Current VPGOOD1,2 = 5.25V MODE Input High Voltage –6 0.35 V 1 2 µA –9 –14 % 0.1 0.2 V 0.01 1 µA 1 V MODE Input Low Voltage MODE Input Current VMODE = 3.3V FSEL Input High Voltage 1 0.35 V 2 µA 0.88 V FSEL Input Low Voltage FSEL Input Current VFSEL = 3.3V Soft-Start Time 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: The LTC3527E/LTC3527E-1 are guaranteed to meet performance specifications from 0°C to 85°C. Specifications over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. Note 3: Current is measured into the VOUT pin since the supply current is bootstrapped to the output. The current will reflect to the input supply by: (VOUT /VIN) • (1/Efficiency). All switches are off. % 1 0.5 0.35 V 2 µA ms Note 4: Specification is guaranteed by design and not 100% tested in production. Note 5: The LTC3527/LTC3527-1 includes an overtemperature shutdown that is intended to protect the device during momentary overload conditions. Junction temperature will exceed 125°C when the overtemperature shutdown is active. Continuous operation above the specified maximum junction temperature may impair device reliability. 35271f 3 LTC3527/LTC3527-1 TYPICAL PERFORMANCE CHARACTERISTICS Efficiency vs Load Current and VIN for VOUT1 = 1.8V at 1.2MHz Efficiency vs Load Current and VIN for VOUT2 = 1.8V at 1.2MHz BURST 90 1.2V EFFICIENCY (%) 70 1.5V FIXED 50 70 1V FIXED 60 50 30 30 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 1.8V 50 30 1000 20 0.01 1000 2.4V FIXED 60 40 100 1 10 LOAD CURRENT (mA) 3V 70 40 0.1 1.8V 80 1.5V 3V BURST 1.2V 1V 40 20 0.01 2.4V 90 BURST 80 1V 60 1.2V 1.5V 90 1V 80 100 1.5V EFFICIENCY (%) 1.2V 0.1 100 1 10 LOAD CURRENT (mA) 1000 35271 G01 35271 G02 35271 G03 Efficiency vs Load Current and VIN for VOUT1 = 3.3V at 2.2MHz Efficiency vs Load Current and VIN for VOUT2 = 3.3V at 1.2MHz Efficiency vs Load Current and VIN for VOUT2 = 3.3V at 2.2MHz 100 2.4V 90 BURST 1.8V 80 2.4V 3V 2.4V 70 1.8V 60 FIXED 50 100 3V 90 1.8V 2.4V 1.8V 70 60 FIXED 50 FIXED 50 30 30 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 35271 G04 100 3.6V 100 1 10 LOAD CURRENT (mA) 35271 G06 100 4.2V 4.2V 1000 Efficiency vs Load Current and VIN for VOUT2 = 5V at 1.2MHz 3.6V 90 4.2V 4.2V 90 BURST 80 3.6V 80 2.4V 2.4V 70 EFFICIENCY (%) EFFICIENCY (%) 0.1 35271 G05 Efficiency vs Load Current and VIN for VOUT1 = 5V at 1.2MHz 60 50 40 3.6V BURST 2.4V 2.4V 70 60 50 40 FIXED 30 20 0.01 20 0.01 1000 1.8V 60 30 1000 1.8V 2.4V 40 100 1 10 LOAD CURRENT (mA) 3V 70 40 0.1 3V BURST 80 40 20 0.01 2.4V 3V BURST 80 EFFICIENCY (%) 90 100 3V EFFICIENCY (%) EFFICIENCY (%) Efficiency vs Load Current and VIN for VOUT1 = 3.3V at 1.2MHz 100 100 EFFICIENCY (%) (TA = 25°C, unless otherwise noted) FIXED 30 0.1 100 1 10 LOAD CURRENT (mA) 1000 35271 G07 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 1000 35271 G08 35271f 4 LTC3527/LTC3527-1 TYPICAL PERFORMANCE CHARACTERISTICS Maximum Output Current vs VIN for Converter 1 800 180 160 OUTPUT CURRENT (mA) VOUT = 5V IIN (µA) 120 100 80 60 600 500 VOUT = 3.3V VOUT = 2.5V 700 Maximum Output Current vs VIN for Converter 2 450 OUTPUT CURRENT (mA) No-Load Input Current vs VIN 140 (TA = 25°C, unless otherwise noted) VOUT = 1.8V 500 400 VOUT = 5V 300 200 40 VOUT = 2.5V 350 VOUT = 1.8V 300 250 200 150 VOUT = 5V 100 0 0.5 1 VOUT = 3.3V VOUT = 2.4V VOUT = 1.8V 20 1.5 2.5 2 3 3.5 4 100 50 0 0.5 4.5 1 1.5 2 VIN (V) 2.5 3 3.5 4 0 0.5 4.5 1 2.5 2 3 3.5 35271 G11 Burst Mode Threshold Current vs VIN for VOUT1 = VOUT2 = 3.3V Burst Mode Threshold Current vs VIN for VOUT1 = VOUT2 = 1.8V 1000 60 45 40 50 100 CONVERTER 1 30 25 20 CONVERTER 2 15 10 ENTER BURST CONVERTER 1 30 CONVERTER 2 20 CONVERTER 1 0 0.7 0.8 0.9 1 1.1 1.2 VIN (V) 1.3 35271 G12 1.4 1.5 ENTER BURST CONVERTER 2 CONVERTER 1 0 LEAVE BURST 40 10 CONVERTER 2 5 10 0.635 0.685 0.735 0.785 0.835 0.885 0.935 VIN (V) LEAVE BURST CONVERTER 1 LOAD CURRENT (mA) LOAD CURRENT (mA) 35 CONVERTER 2 4.5 4 VIN (V) 35271 G10 Minimum Load Resistance During Start-Up vs VIN 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 VIN (V) 3 35271 G14 35271 G13 Oscillator Frequency vs Temperature Burst Mode Threshold Current vs VIN for VOUT1 = VOUT2 = 5V 2.50 70 60 FSEL = 3.3V CONVERTER 1 50 FREQUENCY (MHz) LOAD CURRENT (mA) 1.5 VIN (V) 35271 G09 LOAD RESISTANCE (Ω) VOUT = 3.3V 400 LEAVE BURST 40 30 CONVERTER 2 ENTER BURST 2.00 VIN = 1.2V VOUT = 3.3V 1.50 20 FSEL = 0V CONVERTER 2 10 CONVERTER 1 0 1 1.5 2 2.5 3 VIN (V) 3.5 4 4.5 35271 G15 1.00 –45 –30 –15 0 15 30 45 60 TEMPERATURE (°C) 75 90 35271 G16 35271f 5 LTC3527/LTC3527-1 TYPICAL PERFORMANCE CHARACTERISTICS Current Limit vs Temperature (TA = 25°C, unless otherwise noted) Feedback Voltage vs Temperature Start-Up Voltage vs Temperature 1.205 1.30 0.75 CONVERTER1 0.70 1.10 VIN = 1.2V 1.00 VOUT = 3.3V 0.90 0.80 0.70 VOLTAGE (V) 1.200 FB VOLTAGE (V) CURRENT LIMIT (A) 1.20 1.195 0.65 0.60 0.55 1.190 CONVERTER2 0.50 0.60 0.50 –45 –30 –15 0 15 30 45 60 TEMPERATURE (°C) 75 1.185 –55 –35 –15 90 0.45 –50 5 25 45 65 85 105 125 TEMPERATURE (°C) 35271 G18 –30 30 50 –10 10 TEMPERATURE (°C) 35271 G17 90 35271 G19 RDS(ON) (NMOS and PMOS) vs VOUT Burst Mode Quiescent Current vs VOUT 16 70 RDS(ON) (NMOS and PMOS) Change vs Temperature 0.90 VIN = 1.2V 15 0.80 14 0.70 0.70 PMOS2 13 12 RDS(ON) (Ω) RDS(ON) (Ω) IQ (µA) PMOS2 0.60 NMOS2 0.60 NMOS2 0.50 0.50 PMOS1 PMOS1 NMOS1 11 0.40 NMOS1 0.40 10 1.5 2 2.5 3.5 3 VOUT (V) 4 4.5 5 0.30 1.5 2 2.5 35271 G20 3.5 3 VOUT (V) 4 4.5 5 0.30 –45 –30 –15 0 15 30 45 60 TEMPERATURE (°C) 90 35271 G22 35271 G21 Fixed Frequency Switching Waveform and VOUT Ripple 75 Burst Mode Waveforms SW1 PIN 2V/DIV SW1 PIN 2V/DIV VOUT1 50mV/DIV AC COUPLED VOUT1 10mV/DIV AC COUPLED INDUCTOR CURRENT 200mA/DIV 500µs/DIV VIN1 = 1.2V VOUT1 = 3.3V AT 100mA COUT1 = 10µF 35271 G23 10µs/DIV 35271 G24 VIN1 = 1.2V VOUT1 = 3.3V COUT1 = 10µF 35271f 6 LTC3527/LTC3527-1 TYPICAL PERFORMANCE CHARACTERISTICS (TA = 25°C, unless otherwise noted) VOUT1 Load Step Response Fixed Frequency at 1.2MHz VOUT and IIN During Start-Up VOUT1 100mV/DIV AC COUPLED VOUT1 1V/DIV INPUT CURRENT 200mA/DIV LOAD CURRENT 50mA/DIV SHDN1 PIN 1V/DIV 100µs/DIV 35271 G25 100µs/DIV VOUT1 = 3.3V COUT1 = 10µF VIN = 3.6V VOUT1 = 5V VOUT1 Load Step Response Burst Mode Operation at 1.2MHz VOUT2 Load Step Response Fixed Frequency at 2.2MHz VOUT1 100mV/DIV AC COUPLED VOUT2 100mV/DIV AC COUPLED LOAD CURRENT 50mA/DIV LOAD CURRENT 50mA/DIV 100µs/DIV VIN = 3.6V VOUT1 = 5V 20mA TO 170mA STEP COUT1 = 10µF 35271 G27 50mA TO 150mA STEP COUT1 = 10µF 100µs/DIV VIN = 3.6V VOUT2 = 5V 35271 G26 35271 G28 50mA TO 100mA STEP COUT2 = 10µF 35271f 7 LTC3527/LTC3527-1 PIN FUNCTIONS ⎯S⎯H⎯D⎯N⎯1 (Pin 1): Boost Converter 1 Logic-Controlled Shutdown Input. There is an internal 4MΩ pull-down on this pin. MOSFET. Driver bias is derived from VOUT2. PCB trace length from VOUT2 to the output filter capacitor(s) should be as short and wide as possible. • ⎯S⎯H⎯D⎯N⎯1 = High: Normal free running operation, 1.2MHz/2.2MHz typical operating frequency. • ⎯S⎯H⎯D⎯N⎯1 = Low: Shutdown, quiescent current < 2µA. Note: Both converters must be shut down together to achieve < 2µA quiescent current. FSEL (Pin 10): Logic-Controlled Frequency Select Input. FB1 (Pin 2): Boost Converter 1 Feedback Input to the gm Error Amplifier. Connect resistor divider tap to this pin. The output voltage can be adjusted from 1.6V to 5.25V by: • FSEL = High: 2.2MHz Operation • FSEL = Low: 1.2MHz Operation FB2 (Pin 11): Boost Converter 2 Feedback Input to the gm Error Amplifier. Connect resistor divider tap to this pin. The output voltage can be adjusted from 1.6V to 5.25V by: ⎡ R1 ⎤ VOUT1 = 1 . 20 V • ⎢1 + ⎥ (See Block Diagram) ⎣ R2 ⎦ ⎡ R3 ⎤ VOUT2 = 1 . 20 V • ⎢1 + ⎥ (See Block Diagram) ⎣ R4 ⎦ MODE (Pin 3): Logic-Controlled Mode Input for Both Boost Converters. ⎯ ⎯H⎯D⎯N⎯2 (Pin 12): Boost Converter 2 Logic-Controlled S Shutdown Input. There is an internal 4MΩ pull-down on this pin. • MODE = High: Fixed frequency operation • MODE = Low: Automatic Burst Mode operation MODE pin must be 1V or greater to ensure fixed frequency over all operating conditions. VOUT1 (Pin 5): Boost Converter 1 Output Voltage Sense Input and Drain of the Internal Synchronous Rectifier MOSFET. Driver bias is derived from VOUT1. PCB trace length from VOUT1 to the output filter capacitor(s) should be as short and wide as possible. • ⎯S⎯H⎯D⎯N⎯2 = High: Normal free-running operation, 1.2MHz/2.2MHz typical operating frequency. • ⎯S⎯H⎯D⎯N⎯2 = Low: Shutdown, quiescent current < 2µA. Note: Both converters must be shut down together to achieve < 2µA quiescent current. PGOOD2 (PIN 13): Boost Converter 2 Power Good Comparator Output. This open-drain output is low when VFB is 9% below its regulation voltage. SW1 (Pin 6): Boost Converter 1 Switch Pin. Connect the inductor between SW1 and VIN1. 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 ⎯S⎯H⎯D⎯N⎯1 is low, an internal 100Ω anti-ringing switch is connected from SW1 to VIN1 to minimize EMI. GND (Pin 14): Signal Ground. This pin is used as a ground reference for the internal circuitry of the LTC3527/ LTC3527-1. SW2 (Pin 7): Boost Converter 2 Switch Pin. Connect the inductor between SW2 and VIN2. 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 ⎯S⎯H⎯D⎯N⎯2 is low, an internal 100Ω anti-ringing switch is connected from SW2 to VIN2 to minimize EMI. PGOOD1 (PIN 16) Boost Converter 1 Power Good Comparator Output. This open-drain output is low when VFB is 9% below its regulation voltage. VOUT2 (Pin 8): Boost Converter 2 Output Voltage Sense Input and Drain of the Internal Synchronous Rectifier VIN, VIN1, VIN2 (Pins 15, 4, 9): Battery Input Voltage. See Operation section for more information. Exposed Pad (Pin 17): Backplane. The Exposed Pad is PGND and must be soldered to the PCB ground plane. It serves as the power ground connection for VOUT1 and VOUT2, and as a means of conducting heat away from the package. 35271f 8 LTC3527/LTC3527-1 BLOCK DIAGRAM BULK CONTROL SIGNALS SW1 6 VIN 0.88V TO 5V VIN ANTI-RING VOUT L1 4.7µH VOUT1 VOUT1 1.6V TO 5.25V 5 VIN1 4 CIN 4.7µF SHUTDOWN AND VBIAS – ++ 0.30Ω + 1 0.40Ω PWM LOGIC AND DRIVERS OSC1 START1 SD1 SHDN1 VREF_GD CURRENT SENSE SD1 R1 FB1 – + VC1 + ILIM REF IZERO COMP MODE WAKE1 MODE CONTROL PWM COMP – 2 1.20V R2 COUT1 4.7µF ERROR AMPLIFIER + SLOPE COMPENSATION 16 BURST 1 SLP1 PGOOD1 – + SOFT-START VC CLAMP SD1 TSD FB1 1.20V - 9% CONVERTER 1 15 VIN FSEL 10 OSC1 SLP1 OSC2 SLP2 OSCILLATOR 3 MODE START-UP OSCILLATOR VREF_GD 7 START1 START2 VREF_GD 1.20V GND 1.20V - 9% 14 TSD EXPOSED REFERENCE UVLO THERMAL SD PAD/ PGND 17 SHARED BULK CONTROL SIGNALS SW2 VIN ANTI-RING VOUT VOUT2 L2 4.7µH 9 PWM LOGIC AND DRIVERS OSC2 START2 SD2 SHDN2 VREF_GD SHUTDOWN AND VBIAS – ++ SD2 0.50Ω CURRENT SENSE MODE CONTROL PWM COMP – IZERO COMP MODE WAKE2 VC2 + ILIM REF VOUT2 1.6V TO 5.25V 0.60Ω + 12 8 VIN2 R3 – + FB2 11 1.20V R4 COUT2 4.7µF ERROR AMPLIFIER + SLOPE COMPENSATION 13 SLP2 PGOOD2 – + BURST2 SD2 TSD FB2 SOFT-START VC CLAMP 1.20V - 9% CONVERTER 2 35271f 9 LTC3527/LTC3527-1 OPERATION (Refer to Block Diagram) The LTC3527/LTC3527-1 are dual 1.2MHz/2.2MHz synchronous boost converters housed in a 16-lead 3mm × 3mm QFN package. With the ability to start up and operate from inputs less than 880mV, these devices feature fixed frequency, current mode PWM control for exceptional line and load regulation. The current mode architecture with adaptive slope compensation provides excellent transient load response, requiring minimal output filtering. Internal soft-start and loop compensation simplifies the design process while minimizing the number of external components. Each converter has a separate input supply pin and is operated independently of the other, but they share the same oscillator thus providing in-phase switching. If different input supply voltages are used, the third VIN pin must be wired to the higher of the two supplies and each VOUT must be higher than the highest VIN. Bypass capacitors are recommended on all VIN pins. With low RDS(ON) and low gate charge internal N-channel MOSFET switches and P-channel MOSFET synchronous rectifiers, the LTC3527/LTC3527-1 achieve high efficiency over a wide range of load current. With the MODE pin low, automatic Burst Mode operation maintains high efficiency at very light loads, reducing the quiescent current to just 12µA. If MODE is high, fixed frequency PWM switching provides low voltage ripple on the outputs. Operation can be best understood by referring to the Block Diagram. A PGOOD signal is provided independently for each converter which can be used with the ⎯S⎯H⎯D⎯N pins to provide sequencing of the outputs. The LTC3527-1 provides an instant off feature which discharges VOUT1 or VOUT2 when their respective ⎯S⎯H⎯D⎯N pins go low. A frequency select function allows for 1.2MHz switching (FSEL = Low) or 2.2MHz switching (FSEL = High). Low Voltage Start-Up The LTC3527/LTC3527-1 include an independent start-up oscillator designed to start-up at an input voltage of 0.7V (typical). The two converters can be started together or in either sequence of boost 1 and boost 2 with appropriate control of ⎯S⎯H⎯D⎯N⎯1 and ⎯S⎯H⎯D⎯N⎯2. Soft-start and inrush cur- rent limiting are provided to each converter independently during start-up, as well as during normal mode. When VIN, VOUT1, or VOUT2 exceeds 1.4V (typical), the IC enters normal operating mode. Once the higher of VOUT1 or VOUT2 exceeds VIN by 0.24V, the IC powers itself from the higher VOUT instead of VIN. At this point the internal circuitry has no dependency on the VIN input voltage, eliminating the requirement for a large input capacitor. The input voltage can drop as low as 0.5V. With single-cell operation, the limiting factor for the application becomes the availability of the power source to supply sufficient energy to the outputs at low voltages, and maximum duty cycle, which is clamped at 90% (typical). Note that at low input voltages, small voltage drops due to the higher series resistance of a depleted cell become critical and greatly limit the power delivery capability of the converter. A higher value, low ESR input capacitor can help to improve this to a small degree. Low Noise Fixed Frequency Operation Soft-Start: The LTC3527/LTC3527-1 contain internal circuitry to provide independent soft-start operation to each converter. The soft-start circuitry ramps the peak inductor current from zero to its peak value of 900mA (typical) for converter 1 or 500mA (typical) for converter 2 in approximately 0.5ms, allowing start-up into heavy loads. The soft-start circuitry for both channels is reset in the event of a thermal shutdown or shutdown command. Oscillator: An internal oscillator sets the switching frequency to 1.2MHz if the FSEL pin is below 0.35V, or 2.2MHz if the FSEL pin is above 0.88V. Shutdown: Shutdown is accomplished independently for each converter by pulling its respective ⎯S⎯H⎯D⎯N pin below 0.35V, and enabled by pulling each ⎯S⎯H⎯D⎯N pin above 0.88V. Note that the ⎯S⎯H⎯D⎯N pins can be driven above VIN or VOUT, as long as it is limited to less than the absolute maximum rating. Error Amplifier: The non-inverting input of each transconductance error amplifier is internally connected to the 1.20V reference. The inverting inputs are connected to FB1 for converter 1 and FB2 for converter 2. Clamps 35271f 10 LTC3527/LTC3527-1 OPERATION limit the minimum and maximum error amp output voltages for improved large-signal transient response. Power converter control loop compensation is provided internally. An external resistive voltage divider from VOUT1 (VOUT2) to ground programs the respective output voltage via FB1 (FB2) from 1.6V to 5.25V. ⎡ R1 ⎤ VOUT1 = 1 . 20 V • ⎢1 + ⎥ ⎣ R2 ⎦ ⎡ R3 ⎤ VOUT2 = 1 . 20 V • ⎢1 + ⎥ (See Block Diagram) ⎣ R4 ⎦ Current Sensing: Lossless current sensing converts the peak current signal of each N-channel MOSFET switch into a voltage which is summed with its corresponding internal slope compensation. The summed signals are compared to their respective error amplifier outputs to provide individual peak current control commands for the PWM of each converter. Current Limit: The current limit comparators shut off the N-channel MOSFET switches once their threshold is reached. Each current limit comparator delay time to output is typically 60ns. Peak switch current is limited to approximately 900mA for converter 1 and 500mA for converter 2, independent of input or output voltage. If VOUT1 or VOUT2 falls below 1V, its respective current limit is cut in half. Zero Current Comparator: The zero current comparators monitor the inductor current to the outputs and shut off the synchronous rectifiers when the current reduces to approximately 30mA. This prevents the inductor current from reversing in polarity, improving efficiency at light loads. Synchronous Rectifier: To control inrush current and to prevent the inductor currents from running away when VOUT1 or VOUT2 is close to VIN , the P-channel MOSFET synchronous rectifiers are only enabled when their respective VOUT > (VIN + 0.24V). Anti-Ringing Control: The anti-ringing control connects a resistor across the inductor to prevent high frequency ringing on the SW1 (SW2) pins during discontinuous current mode operation. Although the ringing of the resonant circuit formed by the inductors and CSW (capacitance on SW1 or SW2 pins) is low energy, it can cause EMI radiation. Output Disconnect: The LTC3527/LTC3527-1 are designed to allow true output disconnect by eliminating body diode conduction of the internal P-channel MOSFET rectifiers. This allows VOUT1 and VOUT2 to go to zero volts during shutdown, drawing no current from the input source. It also allows for inrush current limiting at turn-on, minimizing surge currents seen by the input supply. Note that to obtain the advantages of output disconnect, there must not be external Schottky diodes connected between the SW1 (SW2) pins and VOUT1 (VOUT2). The output disconnect feature also allows VOUT1 or VOUT2 to be pulled high, without any reverse current into a battery on VIN. Thermal Shutdown: If the die temperature exceeds 160°C, the device will go into thermal shutdown. All switches will be turned off and the soft-start capacitors will be discharged. The device will be enabled again when the die temperature drops by about 15°C. Burst Mode Operation To realize the efficiency benefits of Burst Mode operation, both VOUT1 and VOUT2 must be under a light load current condition, if they are both enabled. If one channel is shut down, then Burst Mode operation is enabled on the other channel. With the MODE pin low, the LTC3527/LTC3527-1 will automatically enter Burst Mode operation at light load and return to fixed frequency PWM mode when the load increases. Refer to the Typical Performance Characteristics to see the Output Load Burst Mode Threshold Current vs VIN. The load current at which Burst Mode operation is entered can be changed by adjusting the inductor value. Raising the inductor value will lower the load current at which Burst Mode is operation entered. In Burst Mode operation, the LTC3527/LTC3527-1 still switches at a fixed frequency of 1.2MHz (FSEL = 0) or 2.2MHz (FSEL = 1), using the same error amplifier and loop compensation for peak current mode control. This control method eliminates the output transient when switching between modes. In Burst Mode operation, energy is delivered to the output until it reaches the nominal regulation value, then the LTC3527/LTC3527-1 transitions to sleep mode where the outputs are off and the LTC3527/LTC3527-1 consumes only 12µA of quiescent current from the higher of VOUT1 or VOUT2. When 35271f 11 LTC3527/LTC3527-1 OPERATION the output voltage droops slightly, switching resumes. This maximizes efficiency at very light loads by minimizing switching and quiescent current losses. Burst Mode output voltage ripple, which is typically 1% peak-to-peak, can be reduced by using more output capacitance (10µF or greater), or with a small capacitor (10pF to 50pF) connected between VOUT1 (VOUT2) and FB1 (FB2). If either load current increases, the LTC3527/LTC3527-1 will automatically leave Burst Mode operation. Note that larger output capacitor values may cause this transition to occur at lighter loads. Once the LTC3527/LTC3527-1 has left Burst Mode operation and returned to normal operation, it will remain there until both output loads are reduced below the burst threshold current. Burst Mode operation is inhibited during start-up and softstart and until both VOUT1 and VOUT2 are at least 0.24V greater than VIN if neither channel is in shutdown. When the MODE pin is high, LTC3527/LTC3527-1 features continuous PWM fixed frequency operation at 1.2MHz (FSEL = Low) or 2.2MHz (FSEL = High). At very light loads, the LTC3527/LTC3527-1 will exhibit pulse-skip operation. APPLICATIONS INFORMATION VIN > VOUT Operation Schottky Diode The LTC3527/LTC3527-1 will maintain output voltage regulation even when the input voltage is above one or both of the desired output voltages. Since this mode is less efficient and will dissipate more power in the LTC3527/LTC3527-1, the maximum output current capability is limited in order to maintain an acceptable junction temperature. When operating with VIN > VOUT the power is defined by: Although it is not required, adding a Schottky diode from SW1 (SW2) to VOUT1 (VOUT2) will improve efficiency by about 2%. Note that this defeats the output disconnect and short-circuit protection features. POUT = IOUT ⎡⎣( VIN + 1 . 5) − VOUT ⎤⎦ To maintain a junction temperature below 125°C, the following formula must be adhered to: (POUT1 + POUT2 ) 68 °C / W = 125 − TA where TA is the ambient temperature. PCB Layout Guidelines The high speed operation of the LTC3527/LTC3527-1 demands careful attention to board layout. A careless layout will result in reduced performance. Figure 1 shows the recommended component placement. A large ground pin copper area will help to lower the die temperature. A multilayer board with a separate ground plane is ideal, but not absolutely necessary. Short-Circuit Protection COMPONENT SELECTION The LTC3527/LTC3527-1 output disconnect feature allows an output short-circuit while maintaining a maximum internally set current limit. The converters also incorporate internal features such as current limit foldback and thermal shutdown for protection from an excessive overload or short circuit. To reduce power dissipation under shortcircuit conditions, the peak switch current limit is reduced to 500mA (typical) for converter 1 and 350mA (typical) for converter 2 when VOUT is less than 1V. Inductor Selection The LTC3527/LTC3527-1 can utilize small surface mount inductors due to their fast 1.2MHz/2.2MHz switching frequencies. Inductor values between 3.3µH and 4.7µH are suitable for most 1.2MHz applications. Inductor values between 1.5µH and 2.2µH are suitable for most 2.2MHz applications. Larger values of inductance will allow slightly greater output current capability (and lower the Burst 35271f 12 LTC3527/LTC3527-1 APPLICATIONS INFORMATION (series resistance of the windings) to reduce the I2R power losses, and must be able to support the peak inductor current without saturating. Molded chokes and some chip inductors usually do not have enough core area to support the peak inductor currents of 900mA (500mA) seen on the LTC3527/LTC3527-1. To minimize radiated noise, use shielded inductors. See Table 1 for suggested components and suppliers. Mode threshold) by reducing the inductor ripple current. Increasing the inductance above 10µH will increase size while providing little improvement in output current capability. The minimum inductance value is given by: L> VIN(MIN) • ( VOUT(MAX ) – VIN(MIN) ) f • Ripple • VOUT(MAX ) Where: Output and Input Capacitor Selection Ripple = Allowable inductor current ripple (amps peakto-peak) VIN(MIN) = Minimum input voltage VOUT(MAX) = Maximum output voltage f = Oscillator frequency (MHz) Low ESR (equivalent series resistance) capacitors should be used to minimize output voltage ripple. Multilayer ceramic capacitors are an excellent choice as they have extremely low ESR and are available in small footprints. A 4.7µF to 10µF output capacitor is sufficient for most applications. Larger values up to 22µF may be used to obtain lower output voltage ripple and improve transient response. X5R and X7R dielectric materials are preferred for their ability to maintain capacitance over wide voltage and temperature ranges. Y5V types should not be used. The inductor current ripple is typically set for 20% to 40% of the maximum inductor current. 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 MODE SHDN1 GND VIN SHDN2 FSEL GND GND VIN1 VIN2 VOUT1 GND VOUT2 35271 F01 Figure 1. Recommended Component Placement for a Dual-Layer Board 35271f 13 LTC3527/LTC3527-1 APPLICATIONS INFORMATION Table 1. Recommended Inductors PART/STYLE L(µH) MAXIMUM CURRENT (mA) Coilcraft www.coilcraft.com MSS5131 MSS4020 ME3220 2.2-10 3.3-10 1-10 1900-870 1100-540 3000-780 0.023-0.083 0.085-0.210 0.05-0.90 5.1 × 5.1 × 1 4×4×2 3.2 × 2.5 × 2 Coiltronics www.cooperet.com SD10 SD12 1-10 1.2-10 1930-760 2450-818 0.045-0.289 0.037-0.284 5.2 × 5.2 × 1 5.2 × 5.2 × 1.2 MIP3226D MIPF2520D 1.5-6.8 1.5-4.7 1400-1000 1500-1000 0.07-0.12 0.07-0.11 3.2 × 2.6 × 1 2.5 × 2 × 1 Murata www.murata.com LQH43C LQH32C 1-10 1-4.7 1080-650 800-650 0.08-0.24 0.09-0.15 4.5 × 3.2 × 2.6 3.2 × 2.5 × 2 Sumida www.sumida.com CDRH3D16 CDRH2D14 4.7-15 4.7-12 900-450 680-420 0.11-0.29 0.12-0.32 3.8 × 3.8 × 1.8 3.2 × 3.2 × 1.5 TDK www.global.tdk.co.jp VLF3010A VLF5012A 1.5-10 2.2-10 1200-490 1500-800 0.068-0.58 0.090-0.30 2.6 × 2.8 × 1 4.5 × 4.7 × 1.2 NR3010 NR3015 4.7-15 4.7-15 750-400 1000-560 0.19-0.74 0.12-0.36 3×3×1 3 × 3 × 1.5 VENDOR FDK www.fdk.com Taiyo Yuden www.t-yuden.com The internal loop compensation of the LTC3527/ LTC3527-1 is designed to be stable with output capacitor values of 4.7µF or greater. Although ceramic capacitors are recommended, low ESR tantalum capacitors may be used as well. A small ceramic capacitor in parallel with a larger tantalum capacitor may be used in demanding applications which have large load transients. Another method of improving the transient response is to add a small feed-forward capacitor across the top resistor of the feedback divider [from VOUT1 (VOUT2) to FB1 (FB2)]. A typical value of 22pF will generally suffice. Low ESR input capacitors reduce input switching noise and reduce the peak current drawn from the battery. It follows DCR (Ω) DIMENSIONS L×W×H (mm) that ceramic capacitors are also a good choice for input decoupling and should be located as close as possible to the device. A 2.2µF input capacitor is sufficient for most applications, although 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 selection of ceramic parts. Table 2. Capacitor Vendor Information 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 TDK (847) 803-6100 www.component.tdk.com 35271f 14 LTC3527/LTC3527-1 TYPICAL APPLICATIONS 1.2MHz, 1-Cell to VOUT1 = 3V, VOUT2 = 1.8V 0.85V TO 1.60V + SINGLE ALKALINE CELL VOUT 3V 150mA CIN 4.7µF COUT1 4.7µF 4.7µH VIN1 VIN 4.7µH VIN2 SW1 SW2 VOUT1 VOUT2 612k 1.84M FB1 1.21M ON FB2 PGOOD1 MODE 1.21M PGOOD2 SHDN1 OFF VOUT 1.8V 150mA COUT2 4.7µF SHDN2 GND FSEL ON OFF 35271 TA02 L: SUMIDA CDRH3D164R7 CIN, COUT : TAIYO YUDEN X5R JMK212BJ475MD Boost 1 Efficiency Boost 2 Efficiency 100 100 1.2V 90 BURST BURST 80 1.2V 1V 70 1V 60 50 FIXED 50 30 1000 35271 TA02b 1.5V 1V 60 30 100 1 10 LOAD CURRENT (mA) 1V FIXED 40 0.1 1.2V 70 40 20 0.01 1.2V 1.5V 90 1.5V EFFICIENCY (%) EFFICIENCY (%) 80 1.5V 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 1000 35271 TA02c 35271f 15 LTC3527/LTC3527-1 TYPICAL APPLICATIONS 1.2MHz, 1-Cell to VOUT1 = 1.8V, VOUT2 = 5V 0.85V TO 1.60V + SINGLE ALKALINE CELL VOUT 1.8V 200mA CIN 4.7µF COUT1 4.7µF 4.7µH VIN1 VIN 10µH VIN2 SW1 SW2 VOUT1 VOUT2 3.24M 612M FB1 1.21M ON FB2 PGOOD1 MODE 1.02M PGOOD2 SHDN1 OFF VOUT 5V 50mA COUT2 4.7µF SHDN2 GND FSEL ON OFF 35271 TA03 CIN, COUT : TAIYO YUDEN X5R JMK212BJ475MD Boost 1 Efficiency Boost 2 Efficiency 100 1.2V BURST 80 EFFICIENCY (%) 90 1.2V 1.2V 1V 1V 70 1.5V FIXED 60 1.5V 1.5V 80 50 EFFICIENCY (%) 90 100 1.5V 70 1.2V BURST 1V 1V 60 50 40 40 30 30 FIXED 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 1000 35271 TA03b 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 1000 35271 TA03c 35271f 16 LTC3527/LTC3527-1 TYPICAL APPLICATIONS 2.2MHz, 1-Cell to VOUT1 = 3.3V, VOUT2 = 1.8V 0.85V TO 1.60V + SINGLE ALKALINE CELL VOUT 3.3V 150mA CIN 4.7µF COUT1 4.7µF 2.2µH VIN1 VIN SW1 SW2 VOUT1 VOUT2 1M FB2 PGOOD1 MODE 1.21M PGOOD2 SHDN1 OFF VOUT 1.8V 150mA 612k 1.78M FB1 ON 2.2µH VIN2 COUT2 4.7µF SHDN2 GND FSEL ON OFF 35271 TA04 L: SUMIDA CDRH3D162R2 CIN, COUT : TAIYO YUDEN X5R JMK212BJ475MD Boost 1 Efficiency Boost 2 Efficiency 100 100 1.2V 90 1.5V 1.5V 1V 80 1.2V 70 1V 60 FIXED 50 EFFICIENCY (%) EFFICIENCY (%) 80 35271 TA04b 1V FIXED 30 1000 1.2V 1V 50 30 100 1 10 LOAD CURRENT (mA) 1.5V 60 40 0.1 1.5V BURST 70 40 20 0.01 1.2V 90 BURST 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 1000 35271 TA04c 35271f 17 LTC3527/LTC3527-1 TYPICAL APPLICATIONS 1.2MHz, 2-Cell to VOUT1 = 5V, VOUT2 = 3.3V + + 1.8V TO 3.2V CIN 4.7µF ALKALINE CELLS VOUT 5V 300mA COUT1 4.7µF 10µH VIN1 VIN 4.7µH VIN2 SW1 SW2 VOUT1 VOUT2 1.78M 3.24M FB1 1.02M ON FB2 PGOOD1 MODE 1M PGOOD2 SHDN1 OFF VOUT 3.3V 200mA COUT2 4.7µF SHDN2 GND FSEL ON OFF 35271 TA05 L: SUMIDA CDRH3D164R7 CIN, COUT : TAIYO YUDEN X5R JMK212BJ475MD Boost 1 Efficiency Boost 2 Efficiency 100 100 2.4V 90 90 BURST 2.4V 1.8V 1.8V 60 50 40 3V 1.8V 2.4V 1.8V 70 60 FIXED 50 40 FIXED 30 20 0.01 3V BURST 80 EFFICIENCY (%) EFFICIENCY (%) 80 70 2.4V 3V 3V 0.1 30 100 1 10 LOAD CURRENT (mA) 1000 35271 TA05b 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 1000 35271 G05 35271f 18 LTC3527/LTC3527-1 PACKAGE DESCRIPTION UD Package 16-Lead Plastic QFN (3mm × 3mm) (Reference LTC DWG # 05-08-1691) 0.70 ±0.05 3.50 ± 0.05 1.45 ± 0.05 2.10 ± 0.05 (4 SIDES) PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 3.00 ± 0.10 (4 SIDES) BOTTOM VIEW—EXPOSED PAD PIN 1 NOTCH R = 0.20 TYP OR 0.25 × 45° CHAMFER R = 0.115 TYP 0.75 ± 0.05 15 16 PIN 1 TOP MARK (NOTE 6) 0.40 ± 0.10 1 1.45 ± 0.10 (4-SIDES) 2 (UD16) QFN 0904 0.200 REF 0.00 – 0.05 NOTE: 1. DRAWING CONFORMS TO JEDEC PACKAGE OUTLINE MO-220 VARIATION (WEED-2) 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 THE TOP AND BOTTOM OF PACKAGE 0.25 ± 0.05 0.50 BSC 35271f 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. 19 LTC3527/LTC3527-1 TYPICAL APPLICATION Sequenced Start-Up VOUT1 to VOUT2 1.2MHz, 1-Cell to VOUT1 = 1.8V, VOUT2 = 3.3V 0.85V TO 1.60V 100 SINGLE ALKALINE CELL CIN 4.7µF 1.2V 4.7µH VIN1 VIN 90 4.7µH VIN2 SW2 VOUT1 VOUT2 1.78M 612k FB1 ON OFF 1.21M FB2 PGOOD1 1M PGOOD2 SHDN1 MODE VOUT 3.3V 150mA COUT2 4.7µF SHDN2 GND EFFICIENCY (%) COUT1 4.7µF SW1 80 1.2V 70 1.5V FIXED 60 50 1.2V 90 1V 1V 80 VOUT 1.8V 200mA 100 1.5V BURST EFFICIENCY (%) + Boost 2 Efficiency Boost 1 Efficiency 1.5V 1.5V BURST 1V 1.2V 1V 70 60 50 40 40 30 30 FIXED FSEL L: SUMIDA CDRH3D164R7 CIN, COUT : TAIYO YUDEN X5R JMK212BJ475MD 35271 TA06 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 1000 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 35271 TA06b 1000 35271 TA06c RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC3400/ LTC3400B 600mA ISW, 1.2MHz Synchronous Step-Up DC/DC Converters 92% Efficiency, VIN : 0.85V to 5V, VOUT(MAX) = 5V, IQ = 19µA/300µA, ISD < 1µA, ThinSOTTM Package LTC3401 1A ISW, 3MHz Synchronous Step-Up DC/DC Converter 97% Efficiency, VIN : 0.5V to 5V, VOUT(MAX) = 6V, IQ = 38µA, ISD < 1µA, 10-Lead MS Package LTC3421 3A ISW, 3MHz Synchronous Step-Up DC/DC Converter with Output Disconnect 95% Efficiency, VIN : 0.5V to 4.5V, VOUT(MAX) = 5.25V, IQ = 12µA, ISD < 1µA, QFN-24 Package LTC3422 1.5A ISW, 3MHz Synchronous Step-Up DC/DC Converter with Output Disconnect 95% Efficiency, VIN : 0.5V to 4.5V, VOUT(MAX) = 5.25V, IQ = 25µA, ISD < 1µA, 3mm × 3mm DFN Package LTC3423/ LTC3424 2A ISW, 3MHz Synchronous Step-Up DC/DC Converter 97% Efficiency, VIN : 0.5V to 5V, VOUT(MAX) = 6V, IQ = 38µA, ISD < 1µA, 10-Lead MS Package LTC3426 2A ISW, 1.2MHz Synchronous Step-Up DC/DC Converter 92% Efficiency, VIN : 1.6V to 4.3V, VOUT(MAX) = 5V, ISD < 1µA, SOT-23 Package LTC3428 500mA ISW, 1.25MHz/2.5MHz Synchronous Step-Up DC/DC Converter with Output Disconnect 92% Efficiency, VIN : 1.8V to 5V, VOUT(MAX) = 5.25V, ISD < 1µA, 2mm × 2mm DFN Package LTC3429 600mA ISW, 500kHz Synchronous Step-Up DC/DC Converter with Output Disconnect and Soft-Start 96% Efficiency, VIN : 0.5V to 4.4V, VOUT(MAX) = 5V, IQ = 20µA/300µA, ISD < 1µA, ThinSOT Package LTC3458 1.4A ISW, 1.5MHz Synchronous Step-Up DC/DC Converter/ Output Disconnect/Burst Mode Operation 93% Efficiency, VIN : 1.5V to 6V, VOUT(MAX) = 7.5V, IQ = 15µA, ISD < 1µA, DFN-12 Package LTC3458L 1.7A ISW, 1.5MHz Synchronous Step-Up DC/DC Converter with 94% Efficiency, VOUT(MAX ) = 6V, IQ = 12µA, DFN-12 Package Output Disconnect, Automatic Burst Mode Operation LTC3459 70mA ISW, 10V Micropower Synchronous Boost Converter/ Output Disconnect/Burst Mode Operation VIN : 1.5V to 5.5V, VOUT(MAX) = 10V, IQ = 10µA, ISD < 1µA, ThinSOT Package LTC3525L-3 500mA ISW, 1.2MHz Synchronous Step-Up DC/DC Converters with Output Disconnect, Automatic Burst Mode Operation 94% Efficiency, VIN : 0.85V to 5V, VOUT(MAX) = 5.25V, IQ = 7µA, ISD < 1µA, SC70 Package LTC3526/ LTC3526B 500mA ISW, 1.2MHz Synchronous Step-Up DC/DC Converters with Output Disconnect, Automatic Burst Mode Operation (LTC3526), PWM Only (LTC3526B) 94% Efficiency, VIN : 0.85V to 5V, VOUT(MAX) = 5.25V, IQ = 10µA/300µA, ISD < 1µA, 2mm × 2mm DFN Package LTC3528/ LTC3528B 1A, 1MHz Synchronous Step-Up DC/DC Converter with Output 94% Efficiency, VIN : 0.85V to 5V, VOUT(MAX) = 5.25V, IQ = 10µA/300µA, ISD < 1µA, 2mm × 3mm DFN Package Disconnect, Automatic Burst Mode Operation, PWM Only (LTC3528B) ThinSOT is a trademark of Linear Technology Corporation. 35271f 20 Linear Technology Corporation LT 1207 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2007