Features LM3421Q1/LM3423Q1 are Automotive Grade products that are AEC-Q100 grade 1 qualified (-40°C to +125°C operating junction temperature) and similarly LM3421Q0/LM3423Q0 are AEC-Q100 grade 0 qualified (-40°C to +150°C operating junction temperature) VIN range from 4.5V to 75V High-side adjustable current sense 2Ω, 1A Peak MosFET gate driver Input under-voltage and output over-voltage protection PWM and analog dimming Cycle-by-cycle current limit Programmable switching frequency "Zero current" shutdown and thermal shutdown LED output status flag (LM3423/23Q1/23Q0 only) Fault status flag and timer (LM3423/23Q1/23Q0 only) Description The LM3421/23 are versatile high voltage N-channel MosFET controllers for LED drivers . They can be easily configured in buck, boost, buck-boost and SEPIC topologies. This flexibility, along with an input voltage rating of 75V, makes the LM3421/23 ideal for illuminating LEDs in a large family of applications. Adjustable high-side current sense voltage allows for tight regulation of the LED current with the highest efficiency possible. The LM3421/23 uses Predictive Off-time (PRO) control, which is a combination of peak current-mode control and a predictive off-timer. This method of control eases the design of loop compensation while providing inherent input voltage feed-forward compensation. The LM3421/23 devices include a high-voltage startup regulator that operates over a wide input range of 4.5V to 75V. The internal PWM controller is designed for adjustable switching frequencies of up to 2.0 MHz, thus enabling compact solutions. Additional features include "zero current" shutdown, analog dimming, PWM dimming, over-voltage protection, under-voltage lock-out, cycle-by-cycle current limit, and thermal shutdown. The LM3423 also includes an LED output status flag, a fault flag, a programmable fault timer, and a logic input to select the polarity of the dimming output driver. The LM3421Q1/23Q1 are AEC-Q100 grade 1 qualified and LM3421Q0/23Q0 are AEC-Q100 grade 0 qualified. Applications LED Drivers - Buck, Boost, Buck-Boost, and SEPIC Indoor and Outdoor Area SSL Automotive General Illumination Constant-Current Regulators

LM3421   4.50 <= V in Lower  V   <= V in Upper  V   <= 75.00 Ambient Temperature  °C <= 100 What are WEBENCH® tools? Buck Dimming Circuit

Typical Application click for larger image Buck Dimming Circuit	Block Diagram click for larger image Block diagram
Typical Performance click for larger image Buck Tu

Parameters Values Topology Boost, Sepic, Buck-Boost Input Min Voltage 4.5 Volt Input Max Voltage 75 Volt Output Range VIN to 75V Efficiency (peak) 95 % Output Min 3 Volt Output Max 72 Volt Special Features Constant On Time Architecture, High Side Current Sense Adjustable Output Yes On/Off Pin Yes Error Flag Yes Adj Switch Frequency Yes Sync Pin No Step-Down Yes Step-Up Yes Inverting Yes Flyback Yes RegType Switching Controller Temperature Min -40 deg C Temperature Max 125 deg C AEC Q-100 Automotive Grade 0 Automotive Yes PowerWise Yes

Datasheets

Title		Size	Date	Other Language
	LM3421 LM3421Q1 LM3421Q0 LM3423 LM3423Q1 LM3423Q0 N-Channel Controllers for Constant Current LED Drivers	1360 Kbytes	21-Jan-10

Featured Application Notes

Title		Size	Date	Other Language
	AN-1907: Application Note 1907 LM3423 Buck-Boost Configuration Evaluation Board	879 Kbytes	8-Dec-08
	AN-2010: Application Note 2010 LM3423 Buck-Boost 2 Layer Evaluation Board	640 Kbytes	12-Jul-10

More Application Notes

Title		Size	Date	Other Language
	AN-1982: Application Note 1982 Small, Wide Input Voltage Range LM2842 Keeps LEDs Cool	63 Kbytes	15-Jul-09
	AN-1872: Application Note 1872 LM3423 Boost Evaluation Board	764 Kbytes	8-Dec-08	中文
	AN-1969: Application Note 1969 LM3424 Boost Evaluation Board	988 Kbytes	22-Aug-09
	AN-1967: Application Note 1967 LM3424 Buck-Boost Evaluation Board	1027 Kbytes	22-Aug-09
	AN-1985: Application Note 1985 LM3429 Buck-Boost Evaluation Board	705 Kbytes	3-Aug-09
	AN-1986: Application Note 1986 LM3429 Boost Evaluation Board	672 Kbytes	3-Aug-09

Part Number(s) (NSID)	Top View	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM3421MH/NOPB RoHS Status	TSSOP EXP PAD	Full production Lead Time: 6 weeks	Distributor Region Qty AVNET-EM Worldwide 274 DIGIKEY Worldwide 1273 FUTURE Worldwide 740 NEWARK Americas 251 RSL MICRO Asia Pacific 3128	$1.55 each at 1K+ pcs	rail of 92
LM3421MHX/NOPB RoHS Status	TSSOP EXP PAD	Full production Lead Time: 8 weeks	Distributor Region Qty DIGIKEY Worldwide 0 FUTURE Worldwide 1100	$1.55 each at 1K+ pcs	reel of 2500
LM3421Q0MH/NOPB RoHS Status	TSSOP EXP PAD	Full production Lead Time: 14 weeks	Distributor Region Qty ARROW Worldwide 184 AVNET-EM Worldwide 184 DIGIKEY Worldwide 144 FUTURE Worldwide 184 NEWARK Americas 184	$1.90 each at 1K+ pcs	rail of 73
LM3421Q0MHX/NOPB RoHS Status	TSSOP EXP PAD	Full production Lead Time: 6 weeks	Distributor Region Qty DIGIKEY Worldwide 0	$1.90 each at 1K+ pcs	reel of 2500
LM3421Q1MH/NOPB RoHS Status	TSSOP EXP PAD	Full production Lead Time: 14 weeks	Distributor Region Qty ARROW Worldwide 276 AVNET-EM Worldwide 276 DIGIKEY Worldwide 273 FUTURE Worldwide 166 NEWARK Americas 276	$1.75 each at 1K+ pcs	rail of 92
LM3421Q1MHX/NOPB RoHS Status	TSSOP EXP PAD	Full production Lead Time: 14 weeks	Distributor Region Qty DIGIKEY Worldwide 0	$1.75 each at 1K+ pcs	reel of 2500

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/packaging/leadfree.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/quality/green.

National's certificate of product compliance is located at RoHS Status.

Part Number(s) (NSID)	Description	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM3423BBLSCSEV	LM3423 Buck-Boost 2-Layer Low Side Current Sense Evaluation Board	Full production Lead Free (RoHS)	Distributor Region Qty NATIONAL Worldwide 35	$110.00 each	1
General Description: This wide range evaluation board showcases the LM3423 NFET controller used with a buck-boost current regulator. It is designed to drive 4 to 8 LEDs at a maximum average LED current of 700 mA from a DC input voltage of 10 to 70V. The evaluation board showcases most features of the LM3423 including PWM dimming, fault and LED status flags, output overvoltage protection and input under-voltage lockout. It also has a connector footprint (J7) which can mate with an external LED load board allowing for the LEDs to be mounted close to the driver.  Alternatively, the LED+ and LED- banana jacks can be used to connect the LED load. The buck-boost circuit can be easily redesigned for different specifications by changing only a few components (see the Alternate Designs section found at the end of this application note). This board can also be used to evaluate the features and topology of the LM3421 as the LM3423 is a superset of the features and functionality of the LM3421 IC. Contents: LM3423 Buck-Boost 2-Layer Low Side Current Sense Evaluation Board AN-2010 Application Note LM3423 Buck-Boost 2-layer Evaluation Board not included: LM3423 Datasheet

Part Number(s) (NSID)	Description	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM3423MHBSTEVAL	LM3423 - N-Channel Controllers for Constant Current LED Drivers from the PowerWise® Family	Full production Lead Free (RoHS)	Distributor Region Qty DIGIKEY Worldwide 2 FUTURE Worldwide 1 NATIONAL Worldwide 9 NEWARK Americas 3	$110.00 each	1
Description: The evaluation board has been designed to demonstrate the LM3423 low-side controller as a step-up (boost) regulator to deliver constant current to high power LEDs. The LM3423 is a high voltage-low side NFET controller with an adjustable output current sense voltage. Output voltage regulation is based on peak current-mode control which eases the design of loop compensation while providing inherent input voltage feed-forward compensation. The LM3423 includes a high-voltage start-up regulator that operates over a wide input range of 4.5V to 75V. The PWM controller is designed for high speed capability including a switching frequency range to 2.0 MHz. Additional features include "zero" current shutdown, error amplifier, precision reference, logic-compatible DIM input suitable for fast PWM dimming of the output, cycle-by-cycle current limit, LED ready flag, fault flag, programmable fault timer, and thermal shutdown. Contents: LM3423 Assembled Evaluation Board Application Note 1872 for the LM3423 Evaluation Board LM3423 Datasheet

National Semiconductor follows the provisions of the Product Stewardship Guide for Customers (CSP-9-111C2) and Banned Substances and Materials of Interest Specification (CSP-9-111S2) for regulatory environmental compliance. Details may be found at: www.national.com/quality/green. Lead free products are RoHS compliant.

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Part Number(s) (NSID)	Top View	Type	Pins	MSL Rating	Peak Reflow	RoHS Status	CAD Symbols	Models	Package Marking Format
LM3421MH/NOPB		TSSOP EXP PAD	16	1	260	Detail	Download	N/A	NSUZXYTT LM3421 MH
LM3421MHX/NOPB		TSSOP EXP PAD	16	1	260	Detail	Download	N/A	NSUZXYTT LM3421 MH
LM3421Q0MH/NOPB		TSSOP EXP PAD	16	1	260	Detail	Download	N/A	NSUZXYTT LM3421 Q0MH
LM3421Q0MHX/NOPB		TSSOP EXP PAD	16	1	260	Detail	Download	N/A	NSUZXYTT LM3421 Q0MH
LM3421Q1MH/NOPB		TSSOP EXP PAD	16	1	260	Detail	Download	N/A	NSUZXYTT LM3421 Q1MH
LM3421Q1MHX/NOPB		TSSOP EXP PAD	16	1	260	Detail	Download	N/A	NSUZXYTT LM3421 Q1MH

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/packaging/leadfree.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/quality/green.

National's certificate of product compliance is located at RoHS Status.

CAD Symbols and Models Download LM3421 CAD Symbols

Models N/A

LM3421   4.50 <= V in Lower  V   <= V in Upper  V   <= 75.00 Ambient Temperature  °C <= 100 What are WEBENCH® tools?

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM3421MH	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM3421MHX	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM3421Q0MH	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM3421Q0MHX	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM3421Q1MH	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM3421Q1MHX	ABCD150XV1	0	3868	0	0	2595000	2	736338335

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.

For more information on Reliability Metrics, please click here.

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/packaging/leadfree.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/quality/green.

National's certificate of product compliance is located at RoHS Status.

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Automotive LED Lighting Challenges & Solutions Date: 14-Apr-2009 Length: 0:35:00 LED Bulb Replacement Using National LED Drivers & Nuventix SynJet® Coolers on PowerWise Design TV Date: 18-Jun-2009 Length: 0:18:34 National's LED Drivers Deliver High Performance at Low Power Date: 12-Jan-2009 Length: 0:04:55 What's New in Power Management - February 2010 Date: 15-Feb-2010 Length: 0:6:02 Designing LED Driver Circuits Using WEBENCH LED Designer Date: 02-Dec-2009 Length: 0:43:10 LED Driver Design for General Illumination Date: 04-May-2009 Length: 0:36:55