LTC3429B データシートの表示（PDF） - Linear Technology

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LTC3429B

600mA, 500kHz Micropower Synchronous Boost Converter with Output Disconnect

Linear Technology 

LTC3429/LTC3429B

600mA, 500kHz Micropower

Synchronous Boost Converter

with Output Disconnect

FEATURES

■ Up to 96% Efficiency

■ True Output Load Disconnect

■ Inrush Current Limiting and Internal Soft-Start

■ Low Voltage Start-Up: 0.85V

■ Automatic Burst Mode® Operation with IQ ~ 20µA

■ Continuous Switching at Light Loads (LTC3429B)

■ Internal Synchronous Rectifier

■ Current Mode Control with Internal Compensation

■ Short-Circuit Protection

■ 500kHz Fixed Frequency Switching

■ Input Range: 0.5V to 4.4V

■ Output Range: 2.5V to 4.3V (Up to 5V with Schottky)

■ Shutdown Current: <1µA

■ Antiringing Control Minimizes EMI

■ Tiny External Components

■ Low Profile (1mm) SOT-23 Package

U

APPLICATIO S

■ MP3 Players

■ Digital Cameras

■ LCD Bias Supplies

■ Handheld Instruments

■ Wireless Handsets

■ GPS Receivers

DESCRIPTIO

The LTC®3429/LTC3429B are high efficiency synchro-

nous, fixed frequency, step-up DC/DC converters with true

output load disconnect, inrush current limiting and soft-

start in a low profile 6-lead ThinSOTTM package. These

devices are capable of supplying 100mA from a single AA

cell input or 250mA from a 2-cell AA with a 3.3V output.

A switching frequency of 500kHz minimizes overall solu-

tion footprint by allowing the use of tiny, low profile

inductors and ceramic capacitors. Current mode PWM

control with internal compensation reduces external parts

count thereby saving critical board real estate. The LTC3429

shifts automatically to power saving Burst Mode operation

at light loads while the LTC3429B features continuous

switching at light loads. Antiringing control circuitry re-

duces EMI concerns by damping the inductor in discon-

tinuous mode.

The devices also feature low shutdown current of under

1µA. The true output disconnect feature allows the output

to be completely discharged in shutdown. It also limits the

inrush of current during start-up, minimizing surge cur-

rents seen by the input supply.

, LTC and LT are registered trademarks of Linear Technology Corporation. All other

trademarks are the property of their respective owners. Burst Mode is a registered

trademark of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology

Corporation.

TYPICAL APPLICATIO

+

2-CELL

AA

4.7µH

4.7µF

OFF ON

SW

VIN VOUT

LTC3429

SHDN FB

GND

1.02M

604k

VOUT

3.3V

250mA

10µF

3429 F01a

Figure 1. 2-Cell to 3.3V Synchronous Boost Converter

2-Cell to 3.3V Efficiency

100

100

VIN = 3V

90 EFFICIENCY

10

VIN = 2.4V

80

1

70

60

50

40

0.1

VIN = 2.4V

0.1

VIN = 3V 0.01

POWER LOSS

0.001

1

10

100

OUTPUT CURRENT (mA)

0.0001

1000

3429 F01b

3429fa

1

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