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FEATURES

LTC3527/LTC3527-1 Dual 800mA/400mA, 1.2MHz/2.2MHz Synchronous Step-Up DC/DC Converters DESCRIPTION
The LTC(R)3527/LTC3527-1 are dual high efficiency, step-up DC/DC converters in a space saving 16-lead 3mm x 3mm QFN package. Battery life is maximized with a 700mV start-up voltage and operation down to 500mV once started. The SHDN 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 SHDN goes low. Quiescent current in shutdown is less than 2A.
, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.

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 12A Quiescent Current in Burst Mode(R) Operation Inrush Current Limiting and Soft-Start Internal Synchronous Rectifiers Logic-Controlled Shutdown (< 2A) Quick VOUT Discharge (LTC3527-1) 16-Lead, 0.75mm x 3mm x 3mm QFN Package
APPLICATIONS

MP3/Personal Media Players Noise Canceling/Bluetooth Headsets Wireless Mice Portable Medical Instruments
TYPICAL APPLICATION
Two-Cell Alkaline to 3.3V/1.8V Synchronous Boost Converters +
1.6V to 3.2V VIN 4.7F 4.7H VOUT 3.3V 150mA VIN1 SW1 VOUT1 4.7F 1.78M FB1 ON OFF ON OFF
35271 TA01
1.2MHz Efficiency and Power Loss
100 BURST 90 EFFICIENCY 1000
VIN
VIN2 SW2 VOUT2
4.7H
EFFICIENCY (%)
80 70
100 POWER LOSS (mW)
LTC3527 FB2 PGOOD2 SHDN2 GND FSEL PGOOD1 SHDN1 MODE
619k 1.21M
VOUT 1.8V 150mA
60 50 40 30 POWER 20 LOSS 10 BURST 0 0.1 0.01 FIXED FREQUENCY
10
1
1M
0.1 VIN = 2.4V VOUT1 = 3.3V 1 10 100 LOAD CURRENT (mA) 0.01 1000
35271 TA01b
4.7F
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LTC3527/LTC3527-1 ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW PGOOD1 PGOOD2 12 SHDN2 17 11 FB2 10 FSEL 9 5 VOUT1 6 SW1 7 SW2 8 VOUT2 VIN2 GND VIN
VIN, VIN1, VIN2 Voltage ................................. -0.3V to 6V SW1, SW2 Voltage (DC) .............................. -0.3V to 6V (Pulsed < 100ns) ..................................... -0.3V to 7V SHDN1, SHDN2, 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) .........-40C to 85C Junction Temperature ........................................... 125C Storage Temperature Range...................-65C to 125C
16 15 14 13 SHDN1 1 FB1 2 MODE 3 VIN1 4
UD PACKAGE 16-LEAD (3mm x 3mm) PLASTIC QFN TJMAX = 125C, JA = 68C/W EXPOSED PAD (PIN 17) IS PGND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH LTC3527EUD#PBF LTC3527EUD-1#PBF LEAD BASED FINISH LTC3527EUD LTC3527EUD-1 TAPE AND REEL LTC3527EUD#TRPBF LTC3527EUD-1#TRPBF TAPE AND REEL LTC3527EUD#TR LTC3527EUD-1#TR PART MARKING LDDK LCXP PART MARKING LDDK LCXP PACKAGE DESCRIPTION 16-Lead (3mm x 3mm) Plastic QFN 16-Lead (3mm x 3mm) Plastic QFN PACKAGE DESCRIPTION 16-Lead (3mm x 3mm) Plastic QFN 16-Lead (3mm x 3mm) Plastic QFN TEMPERATURE RANGE -40C to 85C -40C to 85C TEMPERATURE RANGE -40C to 85C -40C to 85C
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
PARAMETER Minimum Start-Up Voltage Output Voltage Adjust Range
The denotes the specifications which apply over the full operating temperature range, -40C to 85C. VIN = 1.2V, VOUT1 = VOUT2 = 3.3V, TA = 25C, unless otherwise noted.
CONDITIONS ILOAD = 1mA VOUT1 VOUT1, 0C to 85C VOUT2 VOUT2, 0C to 85C VFB1,2 = 1.20V VSHDN1 = VSHDN2 = 0V, Not Including Switch Leakage, VOUT1 = VOUT2 = 0V Measured on VOUT, VFB1 = VFB2 = 1.5V VFB1 = VFB2 > 1.2V (Note 3) VSW1,2 = 5V, SHDN1,2 = 0V VSW1,2 = 5V, VOUT1,2 = 0V, SHDN1,2 = 0V

MIN 1.7 1.6 1.7 1.6 1.176
TYP 0.7
MAX 0.88 5.25 5.25 5.25 5.25
UNITS V V V V V V nA A A
Feedback Voltage FB1, FB2 Feedback Input Current FB1, FB2 Quiescent Current: Shutdown Quiescent Current: Burst Mode Operation Quiescent Current: Active NMOS Switch Leakage Current PMOS Switch Leakage Current
1.20 1 0.1 12 500 0.1 0.1
1.224 50 2
900 10 10
A A A
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LTC3527/LTC3527-1 ELECTRICAL CHARACTERISTICS
PARAMETER NMOS Switch On-Resistance, SW1 NMOS Switch On-Resistance, SW2 PMOS Switch On-Resistance, SW1 PMOS Switch On-Resistance, SW2 NMOS Current Limit, SW1 NMOS Current Limit, SW2 Current Limit Delay to Output Time Maximum Duty Cycle Minimum Duty Cycle Switching Frequency Switching Frequency SHDN1,2 Input High Voltage SHDN1,2 Input Low Voltage SHDN1,2 Input Current PGOOD1, PGOOD2 Threshold PGOOD1, PGOOD2 Low Voltage PGOOD1, PGOOD2 Leakage Current MODE Input High Voltage MODE Input Low Voltage MODE Input Current FSEL Input High Voltage FSEL Input Low Voltage FSEL Input Current 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 0C to 85C. Specifications over the -40C to 85C 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. VFSEL = 3.3V 1 0.5 VMODE = 3.3V 0.88 0.35 2 1 VSHDN1,2 = 3.3V Referenced to the Feedback Voltage IPGOOD1,2 = 1mA VPGOOD1,2 = 5.25V 1 0.35 2 -6 1 -9 0.1 0.01 (Note 4) VFB1,2 = 1V VFB1,2 = 1.3V VFSEL = 0V VFSEL = 3.3V

The denotes the specifications which apply over the full operating temperature range, -40C to 85C. VIN = 1.2V, VOUT1 = VOUT2 = 3.3V, TA = 25C, unless otherwise noted.
CONDITIONS MIN TYP 0.30 0.50 0.40 0.60 800 400 60 85 0.9 1.9 0.88 0.35 2 -14 0.2 1 90 0 1.2 2.2 1.5 2.8 MAX UNITS mA mA ns % % MHz MHz V V A % V A V V A V V A 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 125C when the overtemperature shutdown is active. Continuous operation above the specified maximum junction temperature may impair device reliability.
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LTC3527/LTC3527-1 TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency vs Load Current and VIN for VOUT1 = 1.8V at 1.2MHz
100 1.2V 90 80 EFFICIENCY (%) 70 60 50 40 30 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 1000
35271 G01
(TA = 25C, unless otherwise noted) Efficiency vs Load Current and VIN for VOUT1 = 3.3V at 1.2MHz
100 2.4V BURST 1.8V 2.4V 1.8V FIXED 3V 3V 90 1.2V 80 EFFICIENCY (%) 1.5V
Efficiency vs Load Current and VIN for VOUT2 = 1.8V at 1.2MHz
100 90 BURST 80 1V FIXED 60 50 40 30 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 1000
35271 G02
1.5V 1.2V
BURST 1V
1.2V 1.5V
1.5V
EFFICIENCY (%)
1V FIXED
70
1V
70 60 50 40 30 20 0.01 0.1 100 1 10 LOAD CURRENT (mA)
1000
35271 G03
Efficiency vs Load Current and VIN for VOUT1 = 3.3V at 2.2MHz
100 2.4V 90 80 EFFICIENCY (%) 70 60 FIXED 50 40 30 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 1000
35271 G04
Efficiency vs Load Current and VIN for VOUT2 = 3.3V at 1.2MHz
100 2.4V BURST 1.8V 2.4V 1.8V 3V 100 3V 90 80 EFFICIENCY (%) 70 60 90
Efficiency vs Load Current and VIN for VOUT2 = 3.3V at 2.2MHz
2.4V BURST 1.8V 1.8V 2.4V 3V 3V
3V 2.4V
3V 80 EFFICIENCY (%) 1.8V 70 60
BURST 1.8V
FIXED 50 40 30 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 1000
35271 G05
FIXED 50 40 30 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 1000
35271 G06
Efficiency vs Load Current and VIN for VOUT1 = 5V at 1.2MHz
100 3.6V 90 BURST 80 EFFICIENCY (%) 70 60 50 40 FIXED 30 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 1000
35271 G07
Efficiency vs Load Current and VIN for VOUT2 = 5V at 1.2MHz
100 3.6V 90 BURST 2.4V 2.4V 4.2V 4.2V 3.6V
4.2V
4.2V 3.6V
2.4V EFFICIENCY (%) 2.4V
80 70 60 50 40 30 20 0.01
FIXED
0.1
100 1 10 LOAD CURRENT (mA)
1000
35271 G08
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LTC3527/LTC3527-1 TYPICAL PERFORMANCE CHARACTERISTICS
No-Load Input Current vs VIN
180 160 OUTPUT CURRENT (mA) 140 120 IIN (A) 100 80 60 40 20 0 0.5 VOUT = 1.8V 1 1.5 2 VOUT = 2.4V 2.5 VIN (V)
35271 G09
(TA = 25C, unless otherwise noted) Maximum Output Current vs VIN for Converter 2
500 450 OUTPUT CURRENT (mA) 400 350 300 250 200 150 100 VOUT = 5V VOUT = 1.8V VOUT = 3.3V VOUT = 2.5V
Maximum Output Current vs VIN for Converter 1
800 700 VOUT = 2.5V VOUT = 1.8V VOUT = 3.3V
VOUT = 5V
600 500 400 300 200 100
VOUT = 5V
VOUT = 3.3V
50 1 1.5 2 2.5 VIN (V)
35271 G10
3
3.5
4
4.5
0 0.5
3
3.5
4
4.5
0 0.5
1
1.5
2
2.5 VIN (V)
3
3.5
4
4.5
35271 G11
Minimum Load Resistance During Start-Up vs VIN
1000 45 40 LOAD RESISTANCE () 35 LOAD CURRENT (mA) 30 25 20 15 10 5 10 0.635 0.685 0.735 0.785 0.835 0.885 0.935 VIN (V)
35271 G12
Burst Mode Threshold Current vs VIN for VOUT1 = VOUT2 = 1.8V
60 50 CONVERTER 1 LEAVE BURST LOAD CURRENT (mA)
Burst Mode Threshold Current vs VIN for VOUT1 = VOUT2 = 3.3V
CONVERTER 1 40 30 20 10 CONVERTER 2
LEAVE BURST
CONVERTER 2 100
CONVERTER 2
ENTER BURST
ENTER BURST
CONVERTER 1
CONVERTER 2 CONVERTER 1
CONVERTER 2 CONVERTER 1 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 VIN (V)
35271 G14
0 0.7 0.8 0.9 1 1.1 1.2 VIN (V) 1.3 1.4 1.5
0
3
35271 G13
Burst Mode Threshold Current vs VIN for VOUT1 = VOUT2 = 5V
70 60 LOAD CURRENT (mA) 50 40 30 CONVERTER 2 20 10 0 1 1.5 2 CONVERTER 2 CONVERTER 1 2.5 3 VIN (V) 3.5 4 4.5 ENTER BURST CONVERTER 1 LEAVE BURST FREQUENCY (MHz) 2.00 2.50
Oscillator Frequency vs Temperature
FSEL = 3.3V
VIN = 1.2V VOUT = 3.3V
1.50 FSEL = 0V
1.00 -45 -30 -15
0 15 30 45 60 TEMPERATURE (C)
75
90
35271 G15
35271 G16
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LTC3527/LTC3527-1 TYPICAL PERFORMANCE CHARACTERISTICS
Current Limit vs Temperature
1.30 CONVERTER1 1.20 CURRENT LIMIT (A) 1.10 FB VOLTAGE (V) VIN = 1.2V 1.00 VOUT = 3.3V 0.90 0.80 0.70 CONVERTER2 0.60 0.50 -45 -30 -15 0 15 30 45 60 TEMPERATURE (C) 75 90 1.185 -55 -35 -15 1.200 VOLTAGE (V) 0.65 0.60 0.55 1.190 0.50 0.45 -50 0.70 1.205
(TA = 25C, unless otherwise noted)
Feedback Voltage vs Temperature
0.75
Start-Up Voltage vs Temperature
1.195
5 25 45 65 85 105 125 TEMPERATURE (C) 35271 G18
-30
30 50 -10 10 TEMPERATURE (C)
70
90
35271 G17
35271 G19
Burst Mode Quiescent Current vs VOUT
16 15 14 RDS(ON) () IQ (A) 13 12 11 10 1.5 2 2.5 3.5 3 VOUT (V) 4 4.5 5 VIN = 1.2V 0.90 0.80 0.70
RDS(ON) (NMOS and PMOS) vs VOUT
PMOS2 0.70
RDS(ON) (NMOS and PMOS) Change vs Temperature
PMOS2 0.60 NMOS2 0.60 0.50 NMOS1 0.40 0.30 1.5 0.30 -45 -30 -15 PMOS1 0.40 RDS(ON) () NMOS2 PMOS1 NMOS1
0.50
2
2.5
3.5 3 VOUT (V)
4
4.5
5
0 15 30 45 60 TEMPERATURE (C)
75
90
35271 G20
35271 G21
35271 G22
Fixed Frequency Switching Waveform and VOUT Ripple
SW1 PIN 2V/DIV SW1 PIN 2V/DIV VOUT1 50mV/DIV AC COUPLED INDUCTOR CURRENT 200mA/DIV 500s/DIV VIN1 = 1.2V VOUT1 = 3.3V AT 100mA COUT1 = 10F
35271 G23
Burst Mode Waveforms
VOUT1 10mV/DIV AC COUPLED
10s/DIV VIN1 = 1.2V VOUT1 = 3.3V COUT1 = 10F
35271 G24
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LTC3527/LTC3527-1 TYPICAL PERFORMANCE CHARACTERISTICS
VOUT and IIN During Start-Up
VOUT1 100mV/DIV AC COUPLED VOUT1 1V/DIV INPUT CURRENT 200mA/DIV SHDN1 PIN 1V/DIV VOUT1 = 3.3V COUT1 = 10F
(TA = 25C, unless otherwise noted) VOUT1 Load Step Response Fixed Frequency at 1.2MHz
LOAD CURRENT 50mA/DIV 100s/DIV
35271 G25
100s/DIV VIN = 3.6V VOUT1 = 5V 50mA TO 150mA STEP COUT1 = 10F
35271 G26
VOUT1 Load Step Response Burst Mode Operation at 1.2MHz
VOUT1 100mV/DIV AC COUPLED VOUT2 100mV/DIV AC COUPLED
VOUT2 Load Step Response Fixed Frequency at 2.2MHz
LOAD CURRENT 50mA/DIV 100s/DIV VIN = 3.6V VOUT1 = 5V 20mA TO 170mA STEP COUT1 = 10F
35271 G27
LOAD CURRENT 50mA/DIV 100s/DIV VIN = 3.6V VOUT2 = 5V 50mA TO 100mA STEP COUT2 = 10F
35271 G28
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LTC3527/LTC3527-1 PIN FUNCTIONS
SHDN1 (Pin 1): Boost Converter 1 Logic-Controlled Shutdown Input. There is an internal 4M pull-down on this pin. * SHDN1 = High: Normal free running operation, 1.2MHz/2.2MHz typical operating frequency. * SHDN1 = Low: Shutdown, quiescent current < 2A. Note: Both converters must be shut down together to achieve < 2A quiescent current. 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: R1 VOUT1 = 1 . 20 V * 1 + (See Block Diagram) R2 MODE (Pin 3): Logic-Controlled Mode Input for Both Boost Converters. * 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. 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 SHDN1 is low, an internal 100 anti-ringing switch is connected from SW1 to VIN1 to minimize EMI. 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 SHDN2 is low, an internal 100 anti-ringing switch is connected from SW2 to VIN2 to minimize EMI. VOUT2 (Pin 8): Boost Converter 2 Output Voltage Sense Input and Drain of the Internal Synchronous Rectifier 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. FSEL (Pin 10): Logic-Controlled Frequency Select Input. * 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: R3 VOUT2 = 1 . 20 V * 1 + (See Block Diagram) R4 SHDN2 (Pin 12): Boost Converter 2 Logic-Controlled Shutdown Input. There is an internal 4M pull-down on this pin. * SHDN2 = High: Normal free-running operation, 1.2MHz/2.2MHz typical operating frequency. * SHDN2 = Low: Shutdown, quiescent current < 2A. Note: Both converters must be shut down together to achieve < 2A 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. GND (Pin 14): Signal Ground. This pin is used as a ground reference for the internal circuitry of the LTC3527/ LTC3527-1. VIN, VIN1, VIN2 (Pins 15, 4, 9): Battery Input Voltage. See Operation section for more information. PGOOD1 (PIN 16) Boost Converter 1 Power Good Comparator Output. This open-drain output is low when VFB is 9% below its regulation voltage. 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.
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LTC3527/LTC3527-1 BLOCK DIAGRAM
SW1 6 L1 4.7H 4 CIN 4.7F 1 OSC1 START1 SD1 SHDN1 VREF_GD SHUTDOWN AND VBIAS VIN1 PWM LOGIC AND DRIVERS SD1 0.40 0.30 CURRENT SENSE ANTI-RING BULK CONTROL SIGNALS VIN VOUT VOUT1 5 VOUT1 1.6V TO 5.25V
VIN 0.88V TO 5V
-
- ++
PWM COMP
MODE CONTROL
MODE WAKE1 FB1 VC1
+
IZERO COMP
R1
+
ILIM REF
- +
2 1.20V R2
COUT1 4.7F
+
BURST 1 SD1 TSD CONVERTER 1
ERROR AMPLIFIER
SLOPE COMPENSATION SLP1 SOFT-START VC CLAMP
16
PGOOD1
- +
FB1 1.20V - 9%
15 VIN FSEL 10 OSCILLATOR 3 MODE VREF_GD START-UP OSCILLATOR START1 START2
OSC1 SLP1 OSC2 SLP2
REFERENCE UVLO THERMAL SD
VREF_GD 1.20V GND 1.20V - 9% 14 TSD EXPOSED PAD/ PGND 17
SHARED BULK CONTROL SIGNALS
7 L2 4.7H 9
SW2 ANTI-RING
VIN
VOUT VOUT2 8 VOUT2 1.6V TO 5.25V
VIN2 OSC2 START2 SD2 SHDN2 VREF_GD SHUTDOWN AND VBIAS
PWM LOGIC AND DRIVERS SD2
0.60 0.50 CURRENT SENSE
12
-
- ++
PWM COMP
MODE CONTROL
MODE WAKE2 VC2
+
IZERO COMP
R3
+
ILIM REF
- +
FB2 11 1.20V R4
COUT2 4.7F
+
BURST2 SD2 TSD CONVERTER 2
ERROR AMPLIFIER
SLOPE COMPENSATION SLP2 SOFT-START VC CLAMP
13
PGOOD2
- +
FB2 1.20V - 9%
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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 x 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 12A. 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 SHDN pins to provide sequencing of the outputs. The LTC3527-1 provides an instant off feature which discharges VOUT1 or VOUT2 when their respective SHDN 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 SHDN1 and SHDN2. 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 SHDN pin below 0.35V, and enabled by pulling each SHDN pin above 0.88V. Note that the SHDN 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
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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 160C, 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 15C. 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 12A of quiescent current from the higher of VOUT1 or VOUT2. When
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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 (10F 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 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: POUT = IOUT ( VIN + 1 . 5) - VOUT To maintain a junction temperature below 125C, the following formula must be adhered to: (POUT1 + POUT2 ) 68 C / W = 125 - TA where TA is the ambient temperature. Short-Circuit Protection 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. Schottky Diode 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. 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. COMPONENT SELECTION 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 3.3H and 4.7H are suitable for most 1.2MHz applications. Inductor values between 1.5H and 2.2H are suitable for most 2.2MHz applications. Larger values of inductance will allow slightly greater output current capability (and lower the Burst
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12
LTC3527/LTC3527-1 APPLICATIONS INFORMATION
Mode threshold) by reducing the inductor ripple current. Increasing the inductance above 10H will increase size while providing little improvement in output current capability. The minimum inductance value is given by: L> Where: Ripple = Allowable inductor current ripple (amps peakto-peak) VIN(MIN) = Minimum input voltage VOUT(MAX) = Maximum output voltage f = Oscillator frequency (MHz) 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 VIN(MIN) * ( VOUT(MAX ) - VIN(MIN) ) f * Ripple * VOUT(MAX ) (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. Output and Input Capacitor Selection 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 4.7F to 10F output capacitor is sufficient for most applications. Larger values up to 22F 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.
MODE SHDN1
VIN
GND
SHDN2 FSEL
GND
GND
VIN1
VIN2
VOUT1
GND
VOUT2
35271 F01
Figure 1. Recommended Component Placement for a Dual-Layer Board
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13
LTC3527/LTC3527-1 APPLICATIONS INFORMATION
Table 1. Recommended Inductors
MAXIMUM CURRENT (mA) 1900-870 1100-540 3000-780 1930-760 2450-818 1400-1000 1500-1000 1080-650 800-650 900-450 680-420 1200-490 1500-800 750-400 1000-560 DCR () 0.023-0.083 0.085-0.210 0.05-0.90 0.045-0.289 0.037-0.284 0.07-0.12 0.07-0.11 0.08-0.24 0.09-0.15 0.11-0.29 0.12-0.32 0.068-0.58 0.090-0.30 0.19-0.74 0.12-0.36 DIMENSIONS LxWxH (mm) 5.1 x 5.1 x 1 4x4x2 3.2 x 2.5 x 2 5.2 x 5.2 x 1 5.2 x 5.2 x 1.2 3.2 x 2.6 x 1 2.5 x 2 x 1 4.5 x 3.2 x 2.6 3.2 x 2.5 x 2 3.8 x 3.8 x 1.8 3.2 x 3.2 x 1.5 2.6 x 2.8 x 1 4.5 x 4.7 x 1.2 3x3x1 3 x 3 x 1.5
VENDOR Coilcraft www.coilcraft.com Coiltronics www.cooperet.com FDK www.fdk.com Murata www.murata.com Sumida www.sumida.com TDK www.global.tdk.co.jp Taiyo Yuden www.t-yuden.com
PART/STYLE MSS5131 MSS4020 ME3220 SD10 SD12 MIP3226D MIPF2520D LQH43C LQH32C CDRH3D16 CDRH2D14 VLF3010A VLF5012A NR3010 NR3015
L(H) 2.2-10 3.3-10 1-10 1-10 1.2-10 1.5-6.8 1.5-4.7 1-10 1-4.7 4.7-15 4.7-12 1.5-10 2.2-10 4.7-15 4.7-15
The internal loop compensation of the LTC3527/ LTC3527-1 is designed to be stable with output capacitor values of 4.7F 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
that ceramic capacitors are also a good choice for input decoupling and should be located as close as possible to the device. A 2.2F 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 AVX Murata Taiyo-Yuden TDK PHONE (803) 448-9411 (714) 852-2001 (408) 573-4150 (847) 803-6100 WEBSITE www.avxcorp.com www.murata.com www.t-yuden.com www.component.tdk.com
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14
LTC3527/LTC3527-1 TYPICAL APPLICATIONS
1.2MHz, 1-Cell to VOUT1 = 3V, VOUT2 = 1.8V
0.85V TO 1.60V
+
SINGLE ALKALINE CELL
CIN 4.7F
4.7H
VIN1 SW1
VIN
VIN2 SW2 VOUT2
4.7H
VOUT 3V 150mA
COUT1 4.7F ON OFF
VOUT1 1.84M FB1 1.21M PGOOD1 SHDN1 MODE GND
612k FB2 PGOOD2 SHDN2 FSEL 1.21M
VOUT 1.8V 150mA
COUT2 4.7F
ON OFF L: SUMIDA CDRH3D164R7 CIN, COUT : TAIYO YUDEN X5R JMK212BJ475MD
35271 TA02
Boost 1 Efficiency
100 90 80 EFFICIENCY (%) 70 60 50 40 30 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 1000 FIXED 1V BURST 1V 1.2V EFFICIENCY (%) 1.2V 1.5V 1.5V 100 90
Boost 2 Efficiency
1.2V 1.5V BURST 80 70 FIXED 60 50 40 30 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 1000 1V 1.5V 1V 1.2V
35271 TA02b
35271 TA02c
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15
LTC3527/LTC3527-1 TYPICAL APPLICATIONS
1.2MHz, 1-Cell to VOUT1 = 1.8V, VOUT2 = 5V
0.85V TO 1.60V
+
SINGLE ALKALINE CELL
CIN 4.7F
4.7H
VIN1 SW1
VIN
VIN2 SW2 VOUT2
10H VOUT 5V 50mA
VOUT 1.8V 200mA
COUT1 4.7F ON OFF
VOUT1 612M FB1 1.21M PGOOD1 SHDN1 MODE GND
3.24M FB2 PGOOD2 SHDN2 FSEL 1.02M
COUT2 4.7F
ON OFF CIN, COUT : TAIYO YUDEN X5R JMK212BJ475MD
35271 TA03
Boost 1 Efficiency
100 1.2V 90 80 EFFICIENCY (%) 70 60 50 40 30 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 1000 FIXED BURST 1V 1.5V EFFICIENCY (%) 1V 1.5V 1.2V 90 100
Boost 2 Efficiency
1.2V 80 70 60 50 40 BURST 1V
1.5V
1.5V 1.2V 1V
FIXED 30 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 1000
35271 TA03b
35271 TA03c
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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
CIN 4.7F
2.2H
VIN1 SW1
VIN
VIN2 SW2 VOUT2
2.2H
VOUT 3.3V 150mA
COUT1 4.7F ON OFF ON OFF
VOUT1 1.78M FB1 1M PGOOD1 SHDN1 MODE GND
612k FB2 PGOOD2 SHDN2 FSEL 1.21M
VOUT 1.8V 150mA
COUT2 4.7F
35271 TA04
L: SUMIDA CDRH3D162R2 CIN, COUT : TAIYO YUDEN X5R JMK212BJ475MD
Boost 1 Efficiency
100 90 BURST 80 EFFICIENCY (%) 70 60 50 40 30 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 1000 FIXED 1V 1V 1.2V EFFICIENCY (%) 80 70 60 1.2V 1.5V 1.5V 100 90
Boost 2 Efficiency
1.2V BURST
1.5V 1.2V
1.5V
1V 1V FIXED
50 40 30 20 0.01 0.1 100 1 10 LOAD CURRENT (mA) 1000
35271 TA04b
35271 TA04c
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17
LTC3527/LTC3527-1 TYPICAL APPLICATIONS
1.2MHz, 2-Cell to VOUT1 = 5V, VOUT2 = 3.3V + +
VOUT 5V 300mA 1.8V TO 3.2V ALKALINE CELLS CIN 4.7F 10H 4.7H VOUT 3.3V 200mA
VIN1 SW1
VIN
VIN2 SW2 VOUT2
COUT1 4.7F ON OFF
VOUT1 3.24M FB1 1.02M PGOOD1 SHDN1 MODE GND
1.78M FB2 PGOOD2 SHDN2 FSEL 1M
COUT2 4.7F
ON OFF L: SUMIDA CDRH3D164R7 CIN, COUT : TAIYO YUDEN X5R JMK212BJ475MD
35271 TA05
Boost 1 Efficiency
100 90 BURST 80 EFFICIENCY (%) 1.8V 70 60 50 40 30 20 0.01 0.1 FIXED 1.8V 2.4V 3V 3V 90 2.4V EFFICIENCY (%) 80 70 60 100
Boost 2 Efficiency
2.4V BURST 1.8V 2.4V 1.8V 3V 3V
FIXED 50 40 30
100 1 10 LOAD CURRENT (mA)
1000
20 0.01
0.1
100 1 10 LOAD CURRENT (mA)
1000
35271 G05
35271 TA05b
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18
LTC3527/LTC3527-1 PACKAGE DESCRIPTION
UD Package 16-Lead Plastic QFN (3mm x 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 0.75 0.05 BOTTOM VIEW--EXPOSED PAD R = 0.115 TYP 15 16 0.40 0.10 1 1.45 0.10 (4-SIDES) 2 PIN 1 NOTCH R = 0.20 TYP OR 0.25 x 45 CHAMFER
3.00 0.10 (4 SIDES) PIN 1 TOP MARK (NOTE 6)
(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
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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
Boost 1 Efficiency
100 1.2V 100 1.5V 1V 1V 1.5V EFFICIENCY (%) 1.2V FIXED 90 80 70 60 50 40 30 0.1 100 1 10 LOAD CURRENT (mA) 1000 20 0.01
Boost 2 Efficiency
+
SINGLE ALKALINE CELL VOUT 1.8V 200mA
CIN 4.7F
4.7H
VIN1 SW1
VIN
VIN2 SW2 VOUT2
4.7H
90 80 EFFICIENCY (%)
BURST
1.2V BURST 1V
1.5V
1.5V 1.2V 1V
COUT1 4.7F ON
VOUT1 612k FB1 1.21M PGOOD1 SHDN1 MODE GND
1.78M FB2 PGOOD2 SHDN2 FSEL 1M
VOUT 3.3V 150mA
70 60 50 40 30 20 0.01
OFF
COUT2 4.7F
FIXED
L: SUMIDA CDRH3D164R7 CIN, COUT : TAIYO YUDEN X5R JMK212BJ475MD
35271 TA06
0.1
100 1 10 LOAD CURRENT (mA)
1000
35271 TA06b
35271 TA06c
RELATED PARTS
PART NUMBER LTC3400/ LTC3400B LTC3401 LTC3421 LTC3422 LTC3423/ LTC3424 LTC3426 LTC3428 LTC3429 LTC3458 LTC3458L LTC3459 LTC3525L-3 LTC3526/ LTC3526B LTC3528/ LTC3528B DESCRIPTION 600mA ISW, 1.2MHz Synchronous Step-Up DC/DC Converters 1A ISW, 3MHz Synchronous Step-Up DC/DC Converter 3A ISW, 3MHz Synchronous Step-Up DC/DC Converter with Output Disconnect 1.5A ISW, 3MHz Synchronous Step-Up DC/DC Converter with Output Disconnect 2A ISW, 3MHz Synchronous Step-Up DC/DC Converter 2A ISW, 1.2MHz Synchronous Step-Up DC/DC Converter 500mA ISW, 1.25MHz/2.5MHz Synchronous Step-Up DC/DC Converter with Output Disconnect 600mA ISW, 500kHz Synchronous Step-Up DC/DC Converter with Output Disconnect and Soft-Start 1.4A ISW, 1.5MHz Synchronous Step-Up DC/DC Converter/ Output Disconnect/Burst Mode Operation COMMENTS 92% Efficiency, VIN : 0.85V to 5V, VOUT(MAX) = 5V, IQ = 19A/300A, ISD < 1A, ThinSOTTM Package 97% Efficiency, VIN : 0.5V to 5V, VOUT(MAX) = 6V, IQ = 38A, ISD < 1A, 10-Lead MS Package 95% Efficiency, VIN : 0.5V to 4.5V, VOUT(MAX) = 5.25V, IQ = 12A, ISD < 1A, QFN-24 Package 95% Efficiency, VIN : 0.5V to 4.5V, VOUT(MAX) = 5.25V, IQ = 25A, ISD < 1A, 3mm x 3mm DFN Package 97% Efficiency, VIN : 0.5V to 5V, VOUT(MAX) = 6V, IQ = 38A, ISD < 1A, 10-Lead MS Package 92% Efficiency, VIN : 1.6V to 4.3V, VOUT(MAX) = 5V, ISD < 1A, SOT-23 Package 92% Efficiency, VIN : 1.8V to 5V, VOUT(MAX) = 5.25V, ISD < 1A, 2mm x 2mm DFN Package 96% Efficiency, VIN : 0.5V to 4.4V, VOUT(MAX) = 5V, IQ = 20A/300A, ISD < 1A, ThinSOT Package 93% Efficiency, VIN : 1.5V to 6V, VOUT(MAX) = 7.5V, IQ = 15A, ISD < 1A, DFN-12 Package
1.7A ISW, 1.5MHz Synchronous Step-Up DC/DC Converter with 94% Efficiency, VOUT(MAX ) = 6V, IQ = 12A, DFN-12 Package Output Disconnect, Automatic Burst Mode Operation 70mA ISW, 10V Micropower Synchronous Boost Converter/ Output Disconnect/Burst Mode Operation 500mA ISW, 1.2MHz Synchronous Step-Up DC/DC Converters with Output Disconnect, Automatic Burst Mode Operation 500mA ISW, 1.2MHz Synchronous Step-Up DC/DC Converters with Output Disconnect, Automatic Burst Mode Operation (LTC3526), PWM Only (LTC3526B) VIN : 1.5V to 5.5V, VOUT(MAX) = 10V, IQ = 10A, ISD < 1A, ThinSOT Package 94% Efficiency, VIN : 0.85V to 5V, VOUT(MAX) = 5.25V, IQ = 7A, ISD < 1A, SC70 Package 94% Efficiency, VIN : 0.85V to 5V, VOUT(MAX) = 5.25V, IQ = 10A/300A, ISD < 1A, 2mm x 2mm DFN Package
1A, 1MHz Synchronous Step-Up DC/DC Converter with Output 94% Efficiency, VIN : 0.85V to 5V, VOUT(MAX) = 5.25V, IQ = 10A/300A, ISD < 1A, 2mm x 3mm DFN Package Disconnect, Automatic Burst Mode Operation, PWM Only (LTC3528B)
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ThinSOT is a trademark of Linear Technology Corporation.
20 Linear Technology Corporation
(408) 432-1900 FAX: (408) 434-0507
LT 1207 * PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2007

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