LM3421_10 Datasheet, PDF (1/48 Pages) National Semiconductor (TI) – N-Channel Controllers for Constant Current LED Drivers

LM3421
LM3421Q1 LM3421Q0
LM3423
LM3423Q1 LM3423Q0
January 21, 2010
N-Channel Controllers for Constant Current LED Drivers
General 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 flexibili-
ty, along with an input voltage rating of 75V, makes the
LM3421/23 ideal for illuminating LEDs in a large family of ap-
plications.
Adjustable high-side current sense voltage allows for tight
regulation of the LED current with the highest efficiency pos-
sible. 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 regu-
lator 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 solu-
tions. Additional features include "zero current" shutdown,
analog dimming, PWM dimming, over-voltage protection, un-
der-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.
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)
■ ^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 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)}
Applications
■ ^{LED Drivers - Buck, Boost, Buck-Boost, and SEPIC}
■ ^{Indoor and Outdoor Area SSL}
■ ^Automotive
■ ^{General Illumination}
■ ^{Constant-Current Regulators}
Typical Boost Application Circuit
© 2010 National Semiconductor Corporation 300673
300673k9
Boost Evaluation Board
9 Series LEDs at 1A
300673b6
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