GM1937 查看數據表（PDF） - Gamma Microelectronics Inc.
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GM1937 Datasheet PDF : 9 Pages
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GM1937
WHITE LED STEP-UP CONVERTER
Description
Features
The GM1937 is a step-up DC/DC converter specifically High Efficiency: 84% Typical
designed to drive white LEDs with a constant current. 36V internal Switch
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 output capacitor can be as small as 0.22µF,
saving space versus alternative solutions. A low 95mV
feedback voltage minimizes power loss for better
Fast 1.2MHz Switching Frequency
Drives Up to three LEDs from a 2.8V
Supply
Drives Up to six LEDs from a 5V
Supply
External Matched LED Current
Uses Tiny 1mm height inductor
Requires Only 0.22 F Output
Capacitor
Low profile TSOT package
Application
Cellular Phones
PDA, Handheld Computers
Digital Cameras
MPS3 Players
GPS Receivers
Typical Application Circuits
VIN
3V to 5V
OFF ON
22µH
1µF VIN
SW
GM1937
CE
FB
GND
0.22µF
R1
6.34Ω
Figure 1
Li-Ion Powered Driver for Three White LEDs
90
85
80
VIN = 3.0V
75
VIN = 3.6V
70
65
60 0
5
10 15 20
LED CURRENT (mA)
1
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