LTC3455(RevA) 查看數據表（PDF） - Linear Technology

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LTC3455
(Rev.:RevA)

Dual DC/DC Converter with USB Power Manager and Li-Ion Battery Charger

Linear Technology 

FEATURES

■ Seamless Transition between Input Power Sources:

Li-Ion Battery, USB, and 5V Wall Adapter

■ Accurate USB Current Limiting (500mA/100mA)

■ Two High Efficiency DC/DC Converters: Up to 96%

■ Thermal Regulation Maximizes Battery Charge

Rate without Risk of Overheating*

■ Full-Featured Li-Ion Battery Charger

■ Hot Swap™ Output for SDIO and Memory Cards

■ Pin-Selectable Burst Mode® Operation

■ Output Disconnect: All Outputs Discharged to

Ground During Shutdown

■ Available in a 4mm × 4mm × 0.75mm 24-Pin

QFN Package

U

APPLICATIO S

■ Handheld Computers

■ Digital Cameras

■ MP3 Players

LTC3455

Dual DC/DC Converter

with USB Power Manager

and Li-Ion Battery Charger

DESCRIPTIO

The LTC®3455 is a complete power management solution

for a variety of portable applications. The device contains

two synchronous step-down DC/DC converters, a USB

power controller, a full-featured Li-Ion battery charger, a

Hot Swap output, a low-battery indicator, and numerous

internal protection features. The LTC3455 provides a

small, simple solution for obtaining power from three

different power sources: a single-cell Li-Ion battery, a USB

port, and a wall adapter. Current drawn from the USB bus

is accurately limited under all conditions. Whenever a USB

or a wall adapter is present, the battery charger is enabled

and all internal power for the device is drawn from the

appropriate external power source. All outputs are dis-

charged to ground during shutdown to provide complete

output disconnect. The device is available in a

4mm × 4mm 24-pin exposed-pad QFN package.

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

trademarks are the property of their respective owners. Hot Swap is a trademark of Linear

Technology Corporation. Burst Mode is a registered trademark of Linear Technology

Corporation. *Protected by U.S. Patent 6522118.

TYPICAL APPLICATIO

USB 5V

1Ω

4.7µF

WALL 5V

1Ω

4.7µF

USB

CONTROLLER

10µF

3.32k

1k

1.24k

0.1µF

2.49k

SINGLE

CELL Li-ION

+

3.3V TO 4.2V

4.7µF

1.8V

1M

LBO

VBAT

2.49M

806k

USB

SUSPEND

USBHP

VMAX

MODE

HSON

ON2

PWRON

RST

PBSTAT

LTC3455

CHRG

WALLFB

ON

HSO

TIMER

PROG

HSI

VBAT

SW2

FB2

AO

SW1

AI

FB1

GND

3455 TA01a

µC

1M 1M

1.8V

ON/OFF

3.3V, HS

1µF

4.7µH

10pF

4.7µH

10pF

249k

80.6k

3.3V

0.5A

10µF

100k

80.6k

1.8V

0.4A

10µF

Efficiency

100

SWITCHER 2

95 VOUT2 = 3.3V

1000

90

85

SWITCHER 1

100

VOUT1 = 1.8V

80

75

70

10

POWER LOSS FOR

65

BOTH OUTPUTS

60

55

VBAT = 3.6V 1

1

10

100

1000

LOAD CURRENT (mA)

3455 TA01b

3455fa

1

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