General Description

The MP1521 is a constant-current Boost Regulator. This IC has three individual current-sensing feedbacks, which are ideal for driving multiple strings of series connected LEDs. The OLS pin is designed for detecting loose or open LED connections.

The IC uses a peak current, constant minimum off-time architecture. The feedback pins measure voltage across sense resistors in series with the LED strings. When supplying a bias current of 20mA, the voltage drop across the sense resistor is only 0.4V to minimize power loss. Either a DC voltage or a PWM signal at the BRT/PWM input can control the LED brightness.

The MP1521 has an on board power MOSFET switch that is protected by current limit, open load shutdown, thermal shutdown, and under voltage lockout.

Features

■ On Board Power MOSFET

■ Drive 9 White LEDs from 2.7V Input

■ Drive 15 White LEDs from 5V Input

■ Up to 90% Efficiency

■ Over 80mA Output Current Capacity

■ Open Load Shutdown

■ Low Current Sensing Feedback Voltage

■ Up to 3 String Current Sensing Feedback

■ Analog and Digital PWM Brightness Control

■ UVLO, Thermal Shutdown

■ Soft Start

■ Internal Current Limit

■ Available in Compact MSOP10 and Tiny 3 mm x 3 mm QFN16 Package

■ Evaluation Boards Available

Applications

■ Handheld Computers, Cell phones, PDAs, Digital and Video Cameras, Small LCD Displays

■ Li Ion and NiMH Battery Applications