download National Semiconductor pdf datasheets LM3421, LM3423 N-Channel Controllers for Constant Current LED Drivers

LM3421, LM3423
N-Channel Controllers for Constant Current LED Drivers

General Description
The LM3421/LM3423 devices are versatile high voltage LED
driver controllers. With the capability to be configured in a
Buck, Boost, Buck-Boost (Flyback), or SEPIC topology, and
an input operating voltage rating of 75V, these controllers are
ideal for illuminating LEDs in a very diverse, large family of
applications.
Adjustable high-side current sense with a typical sense voltage
of 100mV allows for tight regulation of the LED current
with the highest efficiency possible. Output LED current regulation
is based on peak current-mode control with predictive
Off-Time Control. This method of control eases the design of
loop compensation while providing inherent input voltage
feed-forward compensation.
The LM3421/LM3423 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 2.0MHz, thus enabling compact solutions.
Additional features include: “zero” current shutdown,
precision reference, logic compatible DIM input suitable for
fast PWM dimming, 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.


Click here to download National Semiconductor pdf datasheets LM3421, LM3423 N-Channel Controllers for Constant Current LED Drivers

Datasheets Download-National Semiconductor pdf datasheets download