LTC1697EMS データシートの表示（PDF） - Linear Technology

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LTC1697EMS

High Efficiency Low Power 1W CCFL Switching Regulator

Linear Technology 

LTC1697

High Efficiency Low Power

1W CCFL Switching Regulator

FEATURES

■ Operates from Single Li-Ion Battery

■ 2.8V to 5.5V Input Voltage Range

■ Very Low Shutdown Current: <2µA

■ Synchronous Buck Architecture for High Efficiency

■ PWM Dimming Frequency Adjustable with a Single

Capacitor

■ Accurate Lamp Current Maximizes Lamp Lifetime

■ Fixed Frequency Operation at 300kHz

■ Internal or External PWM Dimming

■ Small 10-Pin MSOP Package

U

APPLICATIO S

■ PDAs

■ Handheld Computers

■ Portable Instruments

■ Handheld GPS with Map Display

■ Handheld TV/Video Monitor

DESCRIPTIO

The LTC®1697 is designed to control a single 1W cold

cathode fluorescent lamp (CCFL). An internal PWM dim-

ming system maximizes efficiency and dimming range.

Accurate lamp currents can be set with a single external

resistor.

The LTC1697 includes a synchronous current mode PWM

controller with internal 1A MOSFET switches. It contains

a 300kHz oscillator, 0.8V reference, and internal current

sense. It operates from a 2.8V to 5.5V input voltage. The

LTC1697 also has a thermal limit and a shutdown that

reduces supply current to <2µA.

The LTC1697 is available in the MSOP-10 package.

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

Protected by U.S. Patent 6522116.

TYPICAL APPLICATIO

6

5

27pF

1kV

1

10 2 3 4

VIN

2.8V TO 5.5V

330Ω

0.15µF

CCFL

LAMP

+

Li-Ion

CELL

33µH

200k

10µF

OFF ON

DIMMING INPUT

1V(0%) – 2V(100%)

0.022µF

VIN SW 0VSEN

SHDN

LTC1697

VDIM LAMP

CDIM

RPROG

VC

GND

8.25k

0.1µF

1697 TA01

ICCFL vs RPROG

10

9

8

7

6

5

4

3

2

4k

6k 8k 10k

RPROG (Ω)

20k

1967 TA01b

1697f

1

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