WHITE LED STEP-UP CONVERTER
LM1937
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 0.22µF Output Capacitor
• Moisture Sensitivity Level 3
SOT-23 5L (SOT-25)
APPLICATIONS
• Cellular Phones
• PDAs, Handheld Computers
• Digital Cameras
• MP3 Players
• GPS Receivers
1.SW 2.GND 3.FB 4.SHDN 5.VIN
ORDERING INFORMATION
Device
LM1937SF5
Marking
1937
Package
SOT-23 5L
DESCRIPTION
The LM1937 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 output capacitor can be as small as 0.22µF, saving space versus alternative solutions. A low 95mV
feedback voltage minimizes power loss for better efficiency.
TYPICAL APPLICATION CIRCUIT
Figure 1. Li-Ion Powered Driver for Three White LEDs
Jul. 2010 - Rev. 1.1.1
HTC
-1-
HTC [ HTC KOREA TAEJIN TECHNOLOGY CO. ]
