Description

The TS1937 is a step-up DC/DC converter specifically designed to drive white LEDs with a constant current. The device can drive 2 ~ 12 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. Additional feature include over output voltage limiting when LEDs are disconnected. The TS1937 switches at a fixed frequency of 1.2MHz, allowing the use of tiny, low profile inductors and capacitors to minimize footprint and cost in space consideration applications for cellular phone backlighting or other hand held equipment.

Features

Inherently Matched LED Current
High Efficiency: 88% Typical
Drives Up to 6 LEDs @ Vin 5V
Drives Up to 12 LEDs @ Vin 12~15V
36V Rugged Bipolar Switch
Fast 1.2MHz Switching Frequency
Requires Only 0.22µF Output Capacitor
PWM dimming control 1KHz to 10KHz
Analog dimming control

Application

Cellular Phones
Digital Still Cameras
MP3 Players
White LED Backlighting
PDAs, Handheld computers