MP1528 – 9 LAMP, 36V PRECISION WHITE LED DRIVER

MP1528 Rev. 1.7

www.MonolithicPower.com

5

2/21/2006

MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.

© 2006 MPS. All Rights Reserved.

TM

PIN FUNCTIONS

Pin #

QFN6

MSOP8

Name

Description

1

2

FB

Feedback Input. The MP1528 regulates the voltage across the current sense resistor

between FB and GND. Connect a current sense resistor from the bottom of the LED

string to GND and connect the bottom of the LED string to FB. The regulation

2

3

GND

Ground.

3

4

SW

Power Switch Output. SW is the drain of the internal MOSFET switch. Connect the

power inductor and output rectifier to SW, which can swing between GND and 42V.

4

5

BIAS

Internal Power Input. BIAS powers the internal circuitry and measures the output

voltage for open circuit protection. Connect BIAS to the output at the top of the LED

string. If open circuit protection is not required, BIAS may be connected to the input

source to reduce power consumption of the MP1528.

5

6

EN

Regulator On/Off Control Input. A high voltage applied to EN turns on the converter;

a low voltage turns it off. When not used, connect EN to the input source for

automatic startup. If EN is driven over 6V, place a 100kΩ resistor in series with EN.

Never leave EN floating.

6

7

BRT

Analog or PWM Input for Controlling LED Brightness. When used in analog mode,

apply a DC voltage of 0.27V to 1.2V. This input voltage is attenuated by 1/3 to set

the voltage across the sense resistor at FB. Maximum brightness (20mA) occurs with

an application of 1.2V. To control the brightness in PWM mode, apply a PWM signal

with a minimum voltage less than 0.18V and a maximum voltage greater than 1.2V

(when a voltage less than 0.18V is applied to this pin, the output switch is turned off).

The regulator operates at maximum brightness when more than 1.2V is applied. The

frequency of the PWM signal must be between 100Hz to 400Hz.

1, 8

NC

No Connect