Features • 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 Description The LM3431 is a 3-channel linear current controller combined with a boost switching controller ideal for driving LED backlight panels in space critical applications. The LM3431 drives 3 external NPN transistors or MOSFETs to deliver high accuracy 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 regulator headroom and optimize efficiency. A DIM input pin controls LED brightness from analog or digital control signals. Dimming frequencies up to 25 kHz are possible 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 maintaining 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. Applications • Automotive Infotainment Displays • Small to Medium Format Displays

LM3431   5.00 <= V in Lower  V   <= V in Upper  V   <= 34.00 Ambient Temperature  °C <= 100 What are WEBENCH® tools? MY BRIEFCASE                                       Click any "Briefcase" icon to add an item

Typical Application *click for larger image	Block Diagram click for larger image
Typical Performance *click for larger image

Datasheet

Title		Size	Date	Other Language
	LM3431/LM3431A/LM3431Q/LM3431AQ 3-Channel Constant Current LED Driver with Integrated Boost Controller	591 Kbytes	10-Mar-09

Featured Application Notes

Title		Size	Date	Other Language
	AN-1764: Application Note 1764 LM3431 Evaluation Board	588 Kbytes	10-Jan-08	中文

More Application Notes

Title		Size	Date	Other Language
	AN-1679: Application Note 1679 LED Backlighting Solution with LM3430 and LM3432	2763 Kbytes	18-Sep-07
	AN-1937: Application Note 1937 LM3433 10A to 40A LED Driver Evaluation Board	1559 Kbytes	25-Mar-09
	AN-1907: Application Note 1907 LM3423 Buck-Boost Configuration Evaluation Board	879 Kbytes	8-Dec-08
	AN-1736: Application Note 1736 LM3433 HB LED Driver Evaluation Kit	1011 Kbytes	4-Feb-08
	AN-1793: Application Note 1793 LM3433 4A to 20A LED Driver Evaluation Board	701 Kbytes	25-Aug-08	中文
	AN-1529: Application Note 1529 LM3430 Evaluation Board	2770 Kbytes	21-Aug-07	中文

Design Tools

Title	Size	Date
LM3431 Component Calculator	554 Kbytes	26-Nov-2007

Reference Design

RD-169 - CCFL to LED Conversion Power Supply

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM3431AMH	ABCD150	0	34175	0	0	4234000	1	1201409060
LM3431AMHX	ABCD150	0	34175	0	0	4234000	1	1201409060
LM3431AQMH	ABCD150	0	34175	0	0	4234000	1	1201409060
LM3431AQMHX	ABCD150	0	34175	0	0	4234000	1	1201409060
LM3431MH	ABCD150	0	34175	0	0	4234000	1	1201409060
LM3431MHX	ABCD150	0	34175	0	0	4234000	1	1201409060
LM3431QMH	ABCD150	0	34175	0	0	4234000	1	1201409060
LM3431QMHX	ABCD150	0	34175	0	0	4234000	1	1201409060

Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR. The Long Term Failure Rates were calculated at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress temperature of 150°C to an application temperature of 55°C.

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