Lm3433 Hb Led Driver Evaluation Kit

 The LM3433 is an adaptive constant on-time DC/DC buck
constant current controller designed to drive a high brightness
LEDs (HB LED) at high forward currents. It is a true current
source that provides a constant current with constant ripple
current regardless of the LED forward voltage drop. The
board CAN accept an input voltage ranging from -9V to -14V
w.r.t. GND. The output configuration allows the anodes of
multiple LEDs to be tied directly to the ground referenced
chassis for maximum heat sink efficacy when a negative input
voltage is used.
LM3433 Board Description
The evaluation board is designed to provide a constant cur-
rent in the range of 2A to 9A. With some modification the
board is capable of up to 20A. The LM3433 requires two input
voltages for operation. A positive voltage with respect to GND
is required for the bias and control circuitry and a negative
voltage with respect to GND is required for the main power
input. This allows for the capability of using common anode
LEDs so that the anodes CAN be tied to the ground referenced
chassis. The evaluation board only requires one input voltage
of -12V with respect to GND. The positive voltage is supplied
by the LM5002 circuit. The LM5002 circuit also provides a
UVLO function to remove the possibility of the LM3433 from
drawing high currents low input voltages during startup. Ini-
tially the output current is set at the minimum of approximately
2A with the POT P1 fully counter-clockwise. To set the desired
current level a short may be connected between LED+ and
LED-, then use a current probe and turn the POT clockwise
until the desired current is reached. A PWM dimming FET is
included on-board for testing when the LED CAN be connected
directly next to the board. A shutdown post on J2, ENA, is
included so that startup and shutdown functions CAN be tested
using an external voltage. Included in the kit is a load board
the emulates a high current LED and an LED adapter board
used to place a dimming FET close to a remote LED
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LM3433 Evaluation Board Schematic
LM3433 Evaluation Board Schematic

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