MP1521

High Efficiency

White LED Driver

MP1521 Rev 2.7 10/06/04

www.monolithicpower.com

1

Monolithic Power Systems

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.

Ordering Information

Part Number

∗

Package

Temperature

MP1521EK

MSOP10

-20

° to +85°C

MP1521EQ

QFN16 (3x3)

-20

° to +85°C

EV0005

MP1521EK Evaluation Board

EV0021

MP1521EQ Evaluation Board

∗ For Tape & Reel, add suffix –Z (i.e., MP1521EK–Z)

For Lead Free, add suffix –LF (i.e., MP1521EK–LF–Z)

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

Typical Application Circuit (One String of Six (6) LEDs)

8

7

IN

BRT/PWM

FB1

OLS

SW

10

EN

REF

4

3

2

1

D1

MP1521

L1

6

5

FB2

FB3

White LEDs

BRT/

PWM

EN

GND

OFF

ON

Efficiency vs LED current, 1 string of 6

Using Toko D62CB 47

µHInductor

50

60

70

80

90

100

5

10

15

20

25

LED Current (mA)