LM3431AQ National Semiconductor, LM3431AQ Datasheet

LM3431AQ

Manufacturer Part Number

LM3431AQ

Description

3-Channel Constant Current LED Driver

Manufacturer

National Semiconductor

Datasheet

1.LM3431AQ.pdf (24 pages)

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3-Channel Constant Current LED Driver with Integrated

Boost Controller

General Description

The LM3431 is a 3-channel linear current controller combined

with a boost switching controller ideal for driving LED back-

light panels in space critical applications. The LM3431 drives

3 external NPN transistors or MOSFETs to deliver high ac-

curacy constant current to 3 LED strings. Output current is

adjustable to drive strings in excess of 200 mA. The LM3431

can be expanded to drive as many as 6 LED strings.

The boost controller drives an external NFET switch for step-

up regulation from input voltages between 5V and 36V. The

LM3431 features LED cathode feedback to minimize regula-

tor headroom and optimize efficiency.

A DIM input pin controls LED brightness from analog or digital

control signals. Dimming frequencies up to 25 kHz are pos-

sible with a contrast ratio of 100:1. Contrast ratios greater than

1000:1 are possible at lower dimming frequencies.

The LM3431 eliminates audible noise problems by maintain-

ing constant output voltage regulation during LED dimming.

Additional features include LED short and open protection,

fault delay/error flag, cycle by cycle current limit, and thermal

shutdown for both the IC and LED array. The enhanced

LM3431A features reduced offset voltge for higher accuracy

LED current.

Typical Application Circuit

LM3431/LM3431A/LM3431Q/

300411

LM3431AQ

Features

■

Applications

■

LM3431Q/LM3431AQ are Automotive Grade products

that are AEC-Q100 grade 1 qualified (-40°C to 125°C

operating junction temperature)

3-channel programmable LED current

High accuracy linear current regulation

Analog and digital PWM dimming control

Up to 25kHz dimming frequency

>100:1 contrast ratio

Integrated Boost controller

5V-36V input voltage range

Adjustable switching frequency up to 1MHz

LED short and open protection

Selectable fault shutdown or automatic restart

Programmable fault delay

Programmable cycle by cycle current limit

Output Over Voltage Protection

No Audible Noise

Enable pin

LED Over-Temperature shutdown input

Thermal Shutdown

TSSOP-28 exposed pad package

Automotive Infotainment Displays

Small to Medium Format Displays

www.DataSheet4U.com

March 10, 2009

www.national.com

30041101

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