General 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