Datasheet > L1937

L1937

更新时间： 2024-02-24 18:03:24

品牌	Logo	应用领域
友顺 - UTC		转换器升压转换器
页数	文件大小	规格书
7页	60K
描述
WHITE LED STEP-UP CONVERTER

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L1937 数据手册

UTC L1937

LINEAR INTEGRATED CIRCUIT

WHITE LED STEP-UP

CONVERTER

DESCRIPTION

The UTC L1937 is a step-up DC/DC converter

specifically designed to drive white LEDs with

constant current. The device can drive two, three or

four LEDs in series from Li-Ion cell. Series

SOT-25

connection of the LEDs provides identical LED

currents resulting in uniform brightness and

eliminating the need for ballast resistors. The UTC

LT1937 switches at 1.2MHz, allowing the use of tiny

external components. The output capacitor can be as

small as 0.22 μF, saving space and cost versus

alternative solutions. A low 95mV feedback voltage

minimizes power loss in the current setting resistor for

better efficiency.

SOT-363

FEATURES

* Inherently Matched LED Current

* High Efficiency: 84% Typical

* Drives Up to Four LEDs from a 3.2V Supply

* Drives Up to Six LEDs from a 5V Supply

* 36V Rugged Bipolar Switch

*Pb-free plating product number: L1937L

* Fast 1.2MHz Switching Frequency

* Uses Tiny 1mm Tall Inductors

* Requires Only 0.22μFOutput Capacitor

APPLICATIONS

* Marking code: LTCG

* Cellular Phones

* PDAs, Handheld Computers

* Digital Cameras

* MP3 Players

* GPS Receivers

PIN FUNCTION

PIN NO. PIN NO.

(SOT-25) (SOT-363).

PIN NAME

SYMBOL

FUNCTION

Connect inductor/diode here. Minimize trace area at this pin to

reduce EMI.

Switch

GND

Ground

Connect directly to local ground plane.

Reference voltage is 95mV. Connect cathode of lowest LED and

resistor here. Calculate resistor value according to the formula:

R_FB= 95mV/I_LED

Feedback

Connect to 1.5V or higher to enable device;0.4V or less to

disable device.

Shutdown

SHDN

V_IN

Input Supply

Ground

Input Supply Pin. Must be locally bypassed.

Connect to Pin 2 and to local ground plane

GND

UTC UNISONIC TECHNOLOGIES CO., LTD.

QW-R103-021,A

12 3 4 5 6 7

中文翻译

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