LTC3528B-2 1A, 2MHz Synchronous Step-Up DC/DC Converter in 2mm × 3mm DFN FEATURES DESCRIPTION n The LTC®3528B-2 is a synchronous, fixed frequency step-up DC/DC converter with output disconnect. High efficiency synchronous rectification, in addition to a 700mV start-up voltage and operation down to 500mV once started, provides longer run-time for single or multiple cell battery-powered products. n n n n n n n n n n n n n n Delivers 3.3V at 200mA from a Single Alkaline/ NiMH Cell or 3.3V at 400mA from Two Cells VIN Start-Up Voltage: 700mV 0.50V to 5.5V Input Range 1.6V to 5.25V VOUT Range Up to 94% Efficiency Output Disconnect 2MHz Fixed Frequency Operation VIN > VOUT Operation Integrated Soft-Start Current Mode Control with Internal Compensation Low Noise PWM Operation Internal Synchronous Rectifier Logic Controlled Shutdown: <1μA Anti-Ringing Control Low Profile (2mm × 3mm × 0.75mm) DFN Package A switching frequency of 2MHz minimizes solution footprint by allowing the use of tiny, low profile inductors and ceramic capacitors. The current mode PWM is internally compensated, simplifying the design process. The LTC3528B-2 features continuous switching at light loads. Anti-ringing circuitry reduces EMI by damping the inductor in discontinuous mode. Additional features include a low shutdown current, open-drain power good output, shortcircuit protection and thermal overload protection. APPLICATIONS The LTC3528B-2 is offered in an 8-lead 2mm × 3mm × 0.75mm DFN package. n L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. n n n n Medical Instruments Flash-Based MP3 Players Noise Canceling Headphones Wireless Mice Bluetooth Headsets TYPICAL APPLICATION Efficiency and Power Loss 100 90 2.2μH 1000 VOUT = 3.3V VIN = 2.4V VIN 4.7μF VOUT LTC3528B-2 PGOOD OFF ON SHDN GND 499k 68pF VOUT 3.3V 400mA 10μF FB 70 100 EFFICIENCY 60 50 POWER LOSS 40 10 30 287k POWER LOSS (mW) SW VIN 1.8V TO 3.2V EFFICIENCY (%) 80 20 35282 TA01a 10 0 0.1 1 10 100 1 1000 LOAD CURRENT (mA) 35282 TA01b 3528b2f 1 LTC3528B-2 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) VIN Voltage ................................................... –0.3V to 6V SW Voltage DC............................................................ –0.3V to 6V Pulsed < 100ns ........................................ –0.3V to 7V SHDN, FB Voltage ........................................ –0.3V to 6V VOUT ............................................................. –0.3V to 6V PGOOD......................................................... –0.3V to 6V Operating Temperature Range (Notes 2, 5) .............................................. –40°C to 85°C Junction Temperature ........................................... 125°C Storage Temperature Range................... –65°C to 125°C TOP VIEW SHDN 1 FB 2 PGOOD 3 8 VIN 9 VOUT 4 7 SGND 6 PGND 5 SW DDB PACKAGE 8-LEAD (3mm × 2mm) PLASTIC DFN TJMAX = 125°C, θJA = 76°C/W (NOTE 6) EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING LTC3528BEDDB-2#PBF LTC3528BEDDB-2#TRPBF LDPB PACKAGE DESCRIPTION TEMPERATURE RANGE 8-Lead (3mm × 2mm) Plastic DFN –40°C to 85°C Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based finish parts. 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 l denotes the specifications which apply over the specified operating temperature range of –40°C to 85°C, otherwise specifications are at TA = 25°C. VIN = 1.2V, VOUT = 3.3V, unless otherwise noted. PARAMETER CONDITIONS Minimum Start-Up Voltage ILOAD = 1mA Output Voltage Adjust Range MIN l l 1.7 1.6 l 1.170 TA = 0°C to 85°C Feedback Voltage (Note 7) Feedback Input Current VFB = 1.3V TYP MAX UNITS 0.70 0.88 V 5.25 5.25 V V 1.200 1.230 V 1 50 nA Quiescent Current—Shutdown VSHDN = 0V, Not Including Switch Leakage, VOUT = 0V 0.01 1 μA Quiescent Current—Active Measured on VOUT, Nonswitching (Note 4) 300 500 μA 0.1 10 μA 0.1 10 μA N-Channel MOSFET Switch Leakage Current VSW = 5V P-Channel MOSFET Switch Leakage Current VSW = 5V, VOUT = 0V N-Channel MOSFET Switch On Resistance P-Channel MOSFET Switch On Resistance l N-Channel MOSFET Current Limit Current Limit Delay Time to Output (Note 3) Maximum Duty Cycle VFB = 1.15V l Minimum Duty Cycle VFB = 1.3V l Frequency l 1.0 87 0.175 Ω 0.250 Ω 1.5 A 60 ns 92 % 0 1.8 2.0 2.4 % MHz 3528b2f 2 LTC3528B-2 ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the specified operating temperature range of –40°C to 85°C, otherwise specifications are at TA = 25°C. VIN = 1.2V, VOUT = 3.3V, unless otherwise noted. PARAMETER CONDITIONS MIN SHDN Input High Voltage TYP MAX 0.88 UNITS V SHDN Input Low Voltage 0.25 V 0.3 1 μA –10 –13 % SHDN Input Current VSHDN = 1.2V PGOOD Threshold Percentage Referenced to Feedback Voltage Falling PGOOD Low Voltage IPGOOD = 1mA VOUT = 1.6V, IPGOOD = 1mA 0.05 0.05 0.1 0.2 V V PGOOD Leakage Current VPGOOD = 5.5V 0.01 1 μA 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 LTC3528BE-2 is guaranteed to meet performance specifications from 0°C to 85°C. Specifications over –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. Note 3: Specification is guaranteed by design and not 100% tested in production. –7 Note 4: Current measurements are made when the output is not switching. Note 5: 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. Continuous operation above the specified maximum operating junction temperature may result in device degradation or failure. Note 6: Failure to solder the exposed backside of the package to the PC board ground plane will result in a thermal resistance much higher than 76°C/W. Note 7: The IC is tested in a feedback loop to make the measurement. 3528b2f 3 LTC3528B-2 TYPICAL PERFORMANCE CHARACTERISTICS Efficiency vs Load Current and VIN for VOUT = 1.8V 90 100 10 POWER LOSS 40 30 EFFICIENCY (%) 50 70 50 1 20 VIN = 1V VIN = 1.5V VIN = 2.4V 10 0.1 1000 100 10 LOAD CURRENT (mA) 0 0.1 1 1 1000 100 10 LOAD CURRENT (mA) 35282 G01 35282 G26 Efficiency vs Load Current and VIN for VOUT = 3.3V Efficiency vs Load Current and VIN for VOUT = 5V 90 90 EFFICIENCY EFFICIENCY 80 80 60 50 POWER LOSS 40 30 10 EFFICIENCY (%) 100 1 100 50 POWER LOSS 40 10 VIN = 2.4V VIN = 3.6V VIN = 4.2V 20 10 0.1 1 1000 100 10 LOAD CURRENT (mA) 60 30 VIN = 1.8V VIN = 2.4V VIN = 3V 20 1000 70 1 1 1000 100 10 LOAD CURRENT (mA) 35282 G03 35282 G02 Minimum Load Resistance During Start-Up vs VIN Maximum Output Current vs VIN 800 Start-Up Delay Time vs VIN 130 10000 120 700 110 600 500 DELAY (μs) 1000 RLOAD (Ω) IOUT (mA) POWER LOSS (mW) 70 POWER LOSS (mW) EFFICIENCY (%) 10000 100 1000 100 10 0.1 10 30 VIN = 1V VIN = 1.2V VIN = 1.5V 10 POWER LOSS 40 1 20 100 60 POWER LOSS (mW) 60 EFFICIENCY 80 POWER LOSS (mW) 100 70 0 0.1 1000 90 EFFICIENCY 80 EFFICIENCY (%) Efficiency vs Load Current and VIN for VOUT = 3V 1000 100 (TA = 25°C unless otherwise noted) 400 300 100 100 90 80 70 200 VOUT = 1.8V VOUT = 3.3V VOUT = 5V 100 0 1 1.5 2 3 2.5 VIN (V) 3.5 4 4.5 60 50 10 0.7 0.8 0.9 1 VIN (V) 35282 G05 35282 G06 1 1.5 2 3 2.5 VIN (V) 3.5 4 4.5 35282 G07 3528b2f 4 LTC3528B-2 TYPICAL PERFORMANCE CHARACTERISTICS Oscillator Frequency Change vs VOUT Oscillator Frequency Change vs Temperature RDS(ON) vs VOUT 5 450 0.50 0.25 4 –0.25 FREQUENCY CHANGE (%) 400 0 350 RDS(ON) (mΩ) FREQUENCY CHANGE (%) (TA = 25°C unless otherwise noted) –0.50 –0.75 –1.00 –1.25 300 PMOS 250 200 –1.50 NMOS –1.75 2 2.5 3.5 3 VOUT (V) 4 4.5 100 1.5 5 2 2.5 3.5 3 VOUT (V) 4.5 4 RDS(ON) Change vs Temperature 5 1.190 0 1.185 –10 90 30 –10 10 50 TEMPERATURE (°C) 90 70 35282 G14 START-UP VOLTAGE (mV) VFB (V) 10 –30 Start-Up Voltage vs Temperature 1.195 CHANGE (%) –2 850 20 70 –1 –5 –50 1.200 30 –10 10 50 TEMPERATURE (°C) 0 VFB vs Temperature 30 –30 1 35282 G13 35282 G12 –20 –50 2 –4 –2.00 1.5 3 –3 150 –2.25 NORMALIZED TO 25°C 1.180 –50 –30 35282 G15 50 –10 10 30 TEMPERATURE (°C) 70 90 800 750 700 650 600 –50 –30 30 –10 10 50 TEMPERATURE (°C) 35282 G16 Fixed Frequency VOUT Ripple and Inductor Current Waveforms 70 90 35282 G17 VOUT and IIN During Soft-Start VOUT 1V/DIV VOUT 20mV/DIV IIN 200mA/DIV IL 200mA/DIV SHDN PIN VIN = 1.2V VOUT = 3.3V COUT = 10μF CFF = 33pF IOUT = 100mA L = 2.2μH 500ns/DIV 35282 G19 VIN = 1.2V VOUT = 3.3V COUT = 10μF L = 2.2μH 200μs/DIV 35282 G21 3528b2f 5 LTC3528B-2 TYPICAL PERFORMANCE CHARACTERISTICS (TA = 25°C unless otherwise noted) Load Step Response (3.6V to 5V) Load Step Response (1.2V to 3.3V) VOUT 100mV/DIV VOUT 100mV/DIV LOAD CURRENT 200mA/DIV LOAD CURRENT 100mA/DIV VIN = 3.6V 20μs/DIV VOUT = 5V COUT = 10μF L = 2.2μH LOAD CURRENT = 100mA TO 550mA 35282 G22 20μs/DIV VIN = 1.2V VOUT = 3.3V COUT = 10μF L = 2.2μH LOAD CURRENT = 20mA TO 170mA 35282 G24 PIN FUNCTIONS SHDN (Pin 1): Logic Controlled Shutdown Input. There is an internal 4MΩ pull-down resistor on this pin. • SHDN = High: Normal operation • SHDN = Low: Shutdown, quiescent current < 1μA FB (Pin 2): Feedback Input. Connect resistor divider tap to this pin. The output voltage can be adjusted from 1.6V to 5.25V by: ⎛ R2⎞ VOUT = 1.20V • ⎜1+ ⎟ ⎝ R1⎠ PGOOD (Pin 3): Power Good Comparator Output. This open-drain output is low when VFB < 10% from its regulation voltage. VOUT (Pin 4): Output Voltage Sense and Drain Connection of the Internal Synchronous Rectifier. PCB trace length from VOUT to the output filter capacitor (4.7μF minimum) should be as short and wide as possible. SW (Pin 5): Switch Pin. Connect inductor between SW and VIN. Keep PCB trace lengths as short and wide as possible to reduce EMI. If the inductor current falls to zero, or SHDN is low, an internal anti-ringing switch is connected from SW to VIN to minimize EMI. PGND (Pin 6): Power Ground. Provide a short direct PCB path between PGND and the (–) side of the input and output capacitors. SGND (Pin 7): Signal Ground. Provide a short direct PCB path between SGND and the (–) side of the input and output capacitors. VIN (Pin 8): Battery Input Voltage. Connect a minimum of 1μF ceramic decoupling capacitor from this pin to ground. Exposed Pad (Pin 9): The Exposed Pad must be soldered to the PCB ground plane. It serves as another ground connection and as a means of conducting heat away from the die. 3528b2f 6 LTC3528B-2 BLOCK DIAGRAM L1 2.2μH CIN 4.7μF 8 5 VIN SW ANTI-RING VOUT VSEL VBEST 1 SHDN SHUTDOWN SHUTDOWN WELL SWITCH VB VOUT GATE DRIVERS AND ANTI-CROSS CONDUCTION R2 – + 4M 3 VREF PK COMP VREF PK UVLO UVLO COUT 10μF 2 R1 + – LOGIC CLK VREF FB CLAMP PGOOD + – IZERO COMP ERROR AMP START-UP 3 FB SLOPE COMP IZERO 2MHz OSC VOUT 1.6V TO 5.25V 4 + – VIN 0.7V TO 5V VREF – 10% SOFT-START FB THERMAL SHUTDOWN TSD WAKE PGND SGND EXPOSED PAD 6 7 9 35282 BD 3528b2f 7 LTC3528B-2 OPERATION (Refer to Block Diagram) The LTC3528B-2 is a 2MHz synchronous boost converter housed in an 8-lead 3mm × 2mm DFN package. With the ability to start-up and operate from inputs less than 0.88V, the device features 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 and requires minimal output filtering. Internal soft-start and internal loop compensation simplifies the design process while minimizing the number of external components. With its low RDS(ON) and low gate charge internal N-channel MOSFET switch and P-channel MOSFET synchronous rectifier, the LTC3528-2 achieves high efficiency over a wide range of load current. The LTC3528B-2 features continuous PWM operation at 2MHz. At very light loads, the LTC3528B-2 will exhibit pulse-skip operation. Operation can be best understood by referring to the Block Diagram. LOW VOLTAGE START-UP The LTC3528B-2 includes an independent start-up oscillator designed to operate at an input voltage of 0.70V (typical). Soft-start and inrush current limiting are provided during start-up, as well as normal operating mode. When either VIN or VOUT exceeds 1.6V typical, the IC enters normal operating mode. Once the output voltage exceeds the input by 0.24V, the IC powers itself from 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. The limiting factor for the application becomes the availability of the power source to supply sufficient power to the output at the low voltages, and the maximum duty cycle, which is clamped at 92% typical. Note that at low input voltages, small voltage drops due to series resistance become critical, and greatly limit the power delivery capability of the converter. LOW NOISE FIXED FREQUENCY OPERATION Soft-Start The LTC3528B-2 contains internal circuitry to provide soft-start operation. The internal soft-start circuitry slowly ramps the peak inductor current from zero to its peak value of 1.5A (typical), allowing start-up into heavy loads. The soft-start time is approximately 0.5ms. The soft-start circuitry is reset in the event of a commanded shutdown or a thermal shutdown. Oscillator An internal oscillator sets the frequency of operation to 2MHz. Shutdown The converter is shut down by pulling the SHDN pin below 0.25V, and activated by pulling SHDN above 0.88V. Note that SHDN can be driven above VIN or VOUT, as long as it is limited to less than the absolute maximum rating. Error Amplifier The error amplifier is a transconductance type. The noninverting input is internally connected to the 1.20V reference and the inverting input is connected to FB. Clamps limit the minimum and maximum error amp output voltage for improved large-signal transient response. Power converter control loop compensation is provided internally. A voltage divider from VOUT to ground programs the output voltage via FB from 1.6V to 5.25V. ⎛ R2⎞ VOUT = 1.20V • ⎜1+ ⎟ ⎝ R1⎠ 3528b2f 8 LTC3528B-2 OPERATION (Refer to Block Diagram) Current Sensing Anti-Ringing Control Lossless current sensing converts the peak current signal of the N-channel MOSFET switch into a voltage which is summed with the internal slope compensation. The summed signal is compared to the error amplifier output to provide a peak current control command for the PWM. The anti-ringing control connects a resistor across the inductor to prevent high frequency ringing on the SW pin during discontinuous current mode operation. The ringing of the resonant circuit formed by L and CSW (capacitance on SW pin) is low energy, but can cause EMI radiation. Current Limit Output Disconnect The current limit comparator shuts off the N-channel MOSFET switch once its threshold is reached. The current limit comparator delay to output is typically 60ns. Peak switch current is limited to approximately 1.5A, independent of input or output voltage, unless VOUT falls below 0.7V, in which case the current limit is cut in half. The LTC3528B-2 is designed to allow true output disconnect by eliminating body diode conduction of the internal P-channel MOSFET rectifier. This allows for VOUT to go to zero volts during shutdown, drawing no current from the input source. It also enables inrush current limiting at turnon, minimizing surge currents seen by the input supply. Note that to obtain the advantages of output disconnect, a Schottky diode cannot be connected between SW and VOUT. The output disconnect feature also allows VOUT to be forced above the programmed regulation voltage, without any reverse current into a battery on VIN. Zero Current Comparator The zero current comparator monitors the inductor current to the output and shuts off the synchronous rectifier when this current reduces to approximately 20mA. 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 current from running away when VOUT is close to VIN, the P-channel MOSFET synchronous rectifier is only enabled when VOUT > (VIN + 0.24V). Thermal Shutdown If the die temperature exceeds 160°C, the LTC3528B-2 enters thermal shutdown. All switches will be turned off and the soft-start capacitor will be discharged. The device will be enabled again when the die temperature drops by approximately 15°C. 3528b2f 9 LTC3528B-2 APPLICATIONS INFORMATION VIN > VOUT OPERATION soldered will help to lower the chip temperature. A multilayer board with a separate ground plane is ideal, but not absolutely necessary. The LTC3528B-2 maintains voltage regulation even when the input voltage is above the desired output voltage. Note that the efficiency is much lower in this mode, and the maximum output current capability will be less. Refer to the Typical Performance Characteristics. COMPONENT SELECTION Inductor Selection The LTC3528B-2 can utilize small surface mount chip inductors due to their fast 2MHz switching frequency. Inductor values between 1.5μH and 3.3μH are suitable for most applications. Larger values of inductance will allow slightly greater output current capability by reducing the inductor ripple current. Increasing the inductance above 10μH will increase size while providing little improvement in output current capability. SHORT-CIRCUIT PROTECTION The LTC3528B-2 output disconnect feature allows an output short circuit while maintaining a maximum internally set current limit. To reduce power dissipation under shortcircuit conditions, the peak switch current limit is reduced to 750mA (typical). SCHOTTKY DIODE The minimum inductance value is given by: Although not required, adding a Schottky diode from SW to VOUT will improve efficiency by about 2%. Note that this defeats the output disconnect and short-circuit protection features. L> ( VIN(MIN) • VOUT(MAX) – VIN(MIN) 2 • Ripple • VOUT(MAX) ) µH where: PCB LAYOUT GUIDELINES Ripple = Allowable inductor current ripple (amps peakpeak) The high speed operation of the LTC3528B-2 demands careful attention to board layout. A careless layout will not produce the advertised performance. Figure 1 shows the recommended component placement. A large ground copper area with the package backside metal pad properly VIN(MIN) = Minimum input voltage VOUT(MAX) = Maximum output voltage + VIN SHDN 1 CIN 8 VIN 7 SGND FB 2 LTC3528B-2 PGOOD 3 VOUT 4 COUT 6 PGND 5 SW 35282 F01 MULTIPLE VIAS TO GROUND PLANE Figure 1. Recommended Component Placement for Single Layer Board 3528b2f 10 LTC3528B-2 APPLICATIONS INFORMATION 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 (series resistance of the windings) to reduce the I2R power losses, and must be able to handle the peak inductor current without saturating. Molded chokes and some chip inductors usually do not have enough core area to support the peak inductor currents of 1.5A seen on the LTC3528B-2. To minimize radiated noise, use a shielded inductor. See Table 1 for suggested components and suppliers. Table 1. Recommended Inductors VENDOR PART/STYLE Coilcraft (847) 639-6400 www.coilcraft.com DO1606T, MSS5131, MSS5121 MSS6122, MOS6020 ME3220, DO1608C 1812PS Coiltronics SD12, SD14, SD20 SD25, SD52 Sumida (847) 956-0666 www.sumida.com CD43 CDC5D23B CDRH5D18 TDK VLP, VLF VLCF, SLF, VLS Toko (408) 432-8282 www.tokoam.com D53, D62, D63 D73, D75 Wurth (201) 785-8800 www.we-online.com WE-TPC type M, MH Output and Input Capacitor Selection Low ESR (equivalent series resistance) capacitors should be used to minimize the output voltage ripple. Multilayer ceramic capacitors are an excellent choice as they have extremely low ESR and are available in small footprints. A 10μF to 22μF output capacitor is sufficient for most applications. Values larger than 22μF may be used to obtain extremely low 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 internal loop compensation of the LTC3528B-2 is designed to be stable with output capacitor values of 10μF 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 VOUT to FB). A typical value of 33pF will generally suffice. Low ESR input capacitors reduce input switching noise and reduce the peak current drawn from the battery. It follows that ceramic capacitors are also a good choice for input decoupling and should be located as close as possible to the device. A 10μF input capacitor is sufficient for most applications. 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 3528b2f 11 LTC3528B-2 TYPICAL APPLICATIONS 1 Cell to 1.8V Efficiency 100 90 2.2μH 80 SW VIN 4.7μF 68pF 499k LTC3528B-2 PGOOD OFF ON VOUT 1.8V 250mA VOUT EFFICIENCY (%) VIN 0.88V TO 1.6V 10μF FB SHDN 1M GND 70 60 50 40 30 VIN = 0.9V VIN = 1.2V VIN = 1.5V 20 35282 TA02a 10 0.1 1 10 100 LOAD CURRENT (mA) 1000 35282 TA02b Dual 1 Cell to 1.8V, 3V Sequenced Supply 2.2μH SW VIN 0.88V TO 1.6V VIN 4.7μF 475k VOUT LTC3528B-2 68pF SHDN VOUT2 1M GND VOUT1 VIN PGOOD1 0.5V/DIV 2.2μH SW VIN 4.7μF Output Voltage Sequencing 10μF FB PGOOD OFF ON 499k VOUT1 1.8V 250mA VOUT LTC3528B-2 PGOOD SHDN GND 499k 68pF VOUT2 3V 200mA 200μs/DIV 35282 TA03b 10μF FB 324k 3528 TA03a 3528b2f 12 LTC3528B-2 TYPICAL APPLICATIONS 1 Cell to 3.3V Efficiency 90 2.2μH 80 VIN 4.7μF VOUT LTC3528B-2 68pF 10μF FB PGOOD OFF ON 499k SHDN VOUT 3.3V 200mA 70 EFFICIENCY (%) SW VIN 0.88V TO 1.6V 287k GND 60 50 40 30 35282 TA04a VIN = 0.9V VIN = 1.2V VIN = 1.5V 20 10 1 10 100 LOAD CURRENT (mA) 1000 36282 TA04b 2 Cell to 3.3V Efficiency 100 2.2μH 90 VIN 4.7μF VOUT LTC3528B-2 PGOOD OFF ON SHDN GND 499k 68pF VOUT 3.3V 400mA 10μF FB 287k EFFICIENCY (%) 80 SW VIN 1.8V TO 3.2V 70 60 50 40 30 35282 TA05a VIN = 1.8V VIN = 2.4V VIN = 3V 20 10 0.1 1 10 100 LOAD CURRENT (mA) 1000 35282 TA05b 3528b2f 13 LTC3528B-2 TYPICAL APPLICATIONS 2 Cell to 5V Efficiency 100 90 2.2μH VIN 1.8V TO 3.2V VIN 4.7μF VOUT LTC3528B-2 1M 22μF FB PGOOD OFF ON VOUT 5V 300mA SHDN EFFICIENCY (%) 80 SW 316k GND 70 60 50 40 30 VIN = 1.8V VIN = 2.4V VIN = 3V 20 35282 TA06a 10 0.1 1 10 100 LOAD CURRENT (mA) 1000 35282 TA06b Li-Ion to 5V Efficiency 100 2.2μH 90 VIN 2.7V TO 4.2V VIN 4.7μF LTC3528B-2 PGOOD OFF ON VOUT 5V 400mA VOUT SHDN GND 1M 22μF FB 316k EFFICIENCY (%) 80 SW 70 60 50 40 30 35282 TA07a VIN = 2.8V VIN = 3.6V VIN = 4.2V 20 10 0.1 1 10 100 LOAD CURRENT (mA) 1000 35282 TA07b 3528b2f 14 LTC3528B-2 PACKAGE DESCRIPTION DDB Package 8-Lead Plastic DFN (3mm × 2mm) (Reference LTC DWG # 05-08-1702 Rev B) 0.61 ±0.05 (2 SIDES) 0.70 ±0.05 2.55 ±0.05 1.15 ±0.05 PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 2.20 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 3.00 ±0.10 (2 SIDES) R = 0.115 TYP 5 R = 0.05 TYP 0.40 ± 0.10 8 2.00 ±0.10 (2 SIDES) PIN 1 BAR TOP MARK (SEE NOTE 6) 0.56 ± 0.05 (2 SIDES) 0.200 REF 0.75 ±0.05 0 – 0.05 4 0.25 ± 0.05 1 PIN 1 R = 0.20 OR 0.25 × 45° CHAMFER (DDB8) DFN 0905 REV B 0.50 BSC 2.15 ±0.05 (2 SIDES) BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING CONFORMS TO VERSION (WECD-1) IN JEDEC PACKAGE OUTLINE M0-229 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 3528b2f 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 LTC3528B-2 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 LTC3421 3A (ISW), 3MHz, Synchronous Step-Up DC/DC Converter with Output Disconnect 94% Efficiency VIN: 0.85V to 4.5V, VOUT(MAX) = 5.25V, IQ = 12μA, ISD < 1μA, 4mm × 4mm QFN24 Package LTC3422 1.5A (ISW), 3MHz Synchronous Step-Up DC/DC Converter with Output Disconnect 94% Efficiency VIN: 0.85V to 4.5V, VOUT(MAX) = 5.25V, IQ = 25µA, ISD < 1µA, 3mm × 3mm DFN10 Package LTC3426 2A (ISW), 1.5MHz, Step-Up DC/DC Converter 92% Efficiency VIN: 1.6V to 5.5V, VOUT(MAX) = 5V, IQ = 600µA, ISD < 1μA, ThinSOT Package LTC3427 500mA (ISW), 1.25MHz, Synchronous Step-Up DC/DC Converter with Output Disconnect 94% Efficiency VIN: 1.8V to 5V, VOUT(MAX) = 5.25V, IQ = 350µA ISD < 1µA, 2mm × 2mm DFN6 Package LTC3429/LTC3429B 600mA (ISW), 550kHz, Synchronous Step-Up DC/DC Converter with Output Disconnect and Soft-Start 96% Efficiency VIN: 0.85V to 4.3V, VOUT(MAX) = 5V, IQ = 20μA, ISD < 1μA, ThinSOT Package LTC3458/LTC3458L 1.4A/1.7A (ISW), 1.5MHz, Synchronous Step-Up DC/DC Converter 94% Efficiency VIN: 0.85V to 6V, VOUT(MAX) = 7.5V/6V, IQ = 15μA, ISD < 1μA, 3mm × 4mm DFN12 Package LTC3459 80mA (ISW), Synchronous Step-Up DC/DC Converter 92% Efficiency VIN: 1.5V to 5.5V, VOUT(MAX) = 10V, IQ = 10μA, ISD < 1μA, ThinSOT Package LT®3494/LT3494A 180mA/350mA (ISW), High Efficiency Step-Up DC/DC Converter with Output Disconnect 85% Efficiency VIN: 2.3V to 16V, VOUT(MAX) = 38V, IQ = 65μA, ISD < 1μA, 2mm × 3mm DFN6, ThinSOT Packages LTC3523/LTC3523-2 600mA (ISW), Step-Up and 400mA Synchronous Step-Down 1.2MHz/2.4MHz DC/DC Converters with Output Disconnect 94% Efficiency VIN: 1.8V to 5.5V, VOUT(MAX) = 5.25V, IQ = 45μA, ISD < 1μA, 3mm × 3mm QFN16 LTC3526/LTC3526L LTC3526B 500mA (ISW), 1MHz Synchronous Step-Up DC/DC Converters with Output Disconnect 94% Efficiency, VIN: 0.85V to 5V, VOUT(MAX) = 5.25V, IQ = 9μA, ISD < 1μA, 2mm × 2mm DFN6 Package LTC3527/LTC3527-1 Dual 800mA/400mA (ISW), 2.2MHz, Synchronous Step-Up DC/DC Converter with Output Disconnect 94% Efficiency, VIN: 0.7V to 5V, VOUT(MAX) = 5.25V, IQ = 12μA, ISD < 1μA, 3mm × 3mm QFN16 Package LTC3528/LTC3528B 1A (ISW), 1MHz Synchronous Step-Up DC/DC Converters 94% Efficiency, VIN: 0.7V to 5.5V, VOUT(MAX) = 5.25V, IQ = 12μA, ISD < 1μA, 3mm × 2mm DFN8 Package with Output Disconnect LTC3537 600mA, 2.2MHz Synchronous Step-Up DC/DC Converter with Output Disconnect and 100mA LDO 94% Efficiency, VIN: 0.7V to 5V, VOUT(MAX) = 5.25V, IQ = 30μA, ISD < 1μA, 3mm × 3mm QFN16 Package ThinSOT is a trademark of Linear Technology Corporation. 3528b2f 16 Linear Technology Corporation LT 0708 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2008