LM3424_0910 Datasheet, PDF (1/50 Pages) National Semiconductor (TI) – Constant Current N-Channel Controller with Thermal Foldback for Driving LEDs

LM3424
October 13, 2009
Constant Current N-Channel Controller with Thermal
Foldback for Driving LEDs
General Description
The LM3424 is a versatile high voltage N-channel MosFET
controller for LED drivers . It can be easily configured in buck,
boost, buck-boost and SEPIC topologies. In addition, the
LM3424 includes a thermal foldback feature for temperature
management of the LEDs. This flexibility, along with an input
voltage rating of 75V, makes the LM3424 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 pos-
sible. The LM3424 uses standard peak current-mode control
providing inherent input voltage feed-forward compensation
for better noise immunity. It is designed to provide accurate
thermal foldback with a programmable foldback breakpoint
and slope. In addition, a 2.45V reference is provided.
The LM3424 includes 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 frequen-
cies of up to 2.0 MHz and external synchronization is possible.
The controller is capable of high speed PWM dimming and
analog dimming. Additional features include slope compen-
sation, softstart, over-voltage and under-voltage lock-out, cy-
cle-by-cycle current limit, and thermal shutdown.
The LM3424Q is an Automotive Grade product that is AEC-
Q100 grade 1 qualified.
Features
■ ^{LM3424Q is an Automotive Grade product that is AEC-}
Q100 grade 1 qualified (-40°C to +125°C operating
junction temperarure)
■ ^V_IN ^{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 slope compensation}
■ ^{Programmable, synchronizable switching frequency}
■ ^{Programmable thermal foldback}
■ ^{Programmable softstart}
■ ^{Precision voltage reference}
■ ^{Low power shutdown and thermal shutdown}
Applications
■ ^{LED Drivers - Buck, Boost, Buck-Boost, and SEPIC}
■ ^{Indoor and Outdoor Area SSL}
■ ^Automotive
■ ^{General Illumination}
■ ^{Constant-Current Regulators}
Typical Boost Application Circuit
© 2009 National Semiconductor Corporation 300857
300857k9
300857b6
Boost Evaluation Board
9 Series LEDs at 1A
www.national.com