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參數(shù)資料
| 型號： | L1937 |
| 廠商： | 友順科技股份有限公司 |
| 英文描述： | WHITE LED STEP-UP CONVERTER |
| 中文描述： | 白光LED升壓轉(zhuǎn)換器 |
| 文件頁數(shù)： | 1/7頁 |
| 文件大?。?/td> | 69K |
| 代理商： | L1937 |
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 a
constant current. The device can drive two, three or
four LEDs in series from a Li-Ion cell. Series
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
F, saving space and cost versus
alternative solutions. A low 95mV feedback voltage
minimizes power loss in the current setting resistor for
better efficiency.
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
* Fast 1.2MHz Switching Frequency
* Uses Tiny 1mm Tall Inductors
* Requires Only 0.22 F Output Capacitor
APPLICATIONS
* Marking code: LTCG
* Cellular Phones
* PDAs, Handheld Computers
* Digital Cameras
* MP3 Players
* GPS Receivers
PIN FUNCTION
PIN NO.
(SOT-25)
(SOT-363).
Connect inductor/diode here. Minimize trace area at this pin to
reduce EMI.
2
Ground
GND
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
SHDN
disable device.
5
6
Input Supply
V
IN
Input Supply Pin. Must be locally bypassed.
5
Ground
GND
Connect to Pin 2 and to local ground plane
UTC
UNISONIC TECHNOLOGIES CO., LTD.
1
QW-R103-021,A
SOT-25
1
2
3
4
5
SOT-363
1
*Pb-free plating product number: L1937L
PIN NO.
PIN NAME
SYMBOL
FUNCTION
1
Switch
SW
3
Feedback
FB
4
Shutdown
Connect to 1.5V or higher to enable device;0.4V or less to
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