LM3423_11 Datasheet, PDF (1/14 Pages) National Semiconductor (TI) – LM3423 Buck-Boost 2 Layer Evaluation Board evaluation board showcases most features

LM3423 Buck-Boost 2 Layer
National Semiconductor
Application Note 2010
Evaluation Board
James Patterson
March 7, 2011
Introduction
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 700mA 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 lock-
out. Note that there are two revisions of this PCB. The docu-
mentation for the latest revision (551600305-002 RevA) is
shown first. The schematic, layout and bill of materials for the
first revision (551600305-001 Rev1) can be found at the end
of this document.
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). Note that design modifications can change the system
efficiency. See the LM3423 datasheet for a comprehensive
explanation of the device and application information.
Schematic for 551600305-002 REVA
EFFICIENCY WITH 6 SERIES LEDS AT 700mA
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© 2011 National Semiconductor Corporation 301077
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