Linear Technology Corp.

40V, 2A Buck-Boost Converter

Tony ArmstrongDirector of Product Marketing, Power Products

© 2011 Linear Technology

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Why the Need for the LTC3115-1?1) Regulated Output with Input Above, Below or Equal to VOUT

Enables Continual Operation Even with Wide Input Fluctuations: Example: Automotive Application with Input Ranging from 3.3V in Cold-Crank to 36V Transient During Load-Dump Scenario, when Output Must Be a Continuous 5V

2) Operation from 2.7V to 40V is Ideal for Wide Range of Input Power Sources: From Single/dual/triple-Cell Li-Ion, to USB, FireWire, Wall Adapter or Automotive Inputs

3) When Well-Regulated Output is Required with a Discharging Energy Storage Device, i.e. Battery or SuperCapacitor

4) For 5V Output, LTC3115 can Deliver up to 2A when VIN>6V, and 1A when VIN>3.6

5) Up to 95% Efficiency Maximizes Battery Run-Time and Minimizes Thermal Constraints

6) Very Low IQ (< 50uA) Preserves Battery Life During Standby/Light Load Operation

7) Very Simple, Compact Footprint

© 2011 Linear Technology

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• 2A Monolithic Synchronous Buck-Boost DC/DC Converter

• Regulated Output with Input Voltage Above, Below

or Equal to the Output Voltage

• Wide VIN Range: 2.7V to 40V

• Wide VOUT Range: 2.7V to 40V

• Low Noise Buck-Boost Architecture (<5mVPK-PK in PWM Mode)

LTC3115-1: What Is It?

© 2011 Linear Technology

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LTC3115-1: Key Features

• Wide VIN Range: 2.7V to 40V

• Wide VOUT Range: 2.7V to 40V

• 1A Output Current for VIN ≥ 3.6V, VOUT = 5V

• 2A Output Current in Step-Down Operation for VIN ≥ 6V

• Programmable Frequency: 100kHz to 2MHz

• Supports Synchronization with an External Clock

• Up to 95% Efficiency

• 50μA Burst ModeR Quiescent Current

• Ultralow Noise Buck-Boost PWM

• Internal Soft-Start

• 3μA Supply Current in Shutdown

• Programmable Input Undervoltage Lockout

• Small 4mm × 5mm × 0.75mm DFN Package or Thermally Enhanced 20-Lead TSSOP Package

© 2011 Linear Technology

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LTC3115-1: Typical Application Schematic

© 2011 Linear Technology

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LTC3115-1: Efficiency of Typical Application

VOUT=5V

© 2011 Linear Technology

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LTC3115-1: Packages

© 2011 Linear Technology

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How the LTC3115-1 Fits with Our Other Synchronous Buck-Boost DC/DC Converters

Supplier Linear Tech Linear Tech Linear Tech

Part # LTC3115-1 LTC3112 LTC3789

TopologyMonolithic

Synch Buck/Boost

Monolithic Synch

Buck/Boost

Synch Buck/Boost Controller

VIN Range 2.7V to 40V 2.7V to 15V 4V to 38V

V OUT Range 2.7V to 40V 2.5V to 14V 0.8V to 38V

Efficiency (VIN=12V,

VOUT=5V@1A) 91% 91% 92%

Output Current (VIN>6V, VOUT=5V)

2A 2.5A5A- 4 N-Channel External FETs

Output Current (VIN=3.6V, VOUT=5V)

1A 1.5A 5A

Output Current (VIN=4V, VOUT=12V)

500mA 1A 5A

Frequency (MHz) 100kHz to 2MHz 750kHz 200kHz to 600kHz

Synchronizable Yes Yes Yes

Max Duty Cycle 100% 100% 100%

Quiescent Current (µA) 50μA 50μA 3mA

Output RipplePK-PK

(12VIN to 5VOUT @ 1A)5mVPK-PK 10mVPK-PK 5mVPK-PK

Output RipplePK-PK In BurstMode

50mVPK-PK 70mVPK-PK n/a

Auto BurstMode Yes Yes n/a

Output Current Monitor/Control

No Yes Control on I/O

BurstMode Defeat Yes Yes n/a

Inductor Value 10µH 4.7µH 4.7µHCOUT Type 22µF-Cer 47µF-Cer 330µF-Tant

Package 4 x 5 DFN-16 TSSOP-20E

4 x 5 DFN-16 TSSOP-20E

4x5 QFN-28, SSOP-28

Pricing (1K) $5.35 $4.00/$4.15 $4.65

© 2011 Linear Technology

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LTC3115-1: Typical Applications

© 2011 Linear Technology

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LTC3115-1: Release Schedule

• Data Sheet: Now

• Samples: Now

• Production Release: November 2011