Data Brief
For further information contact your local STMicroelectronics sales office.
February 2008 Rev 1 1/4
4
STEVAL-ILL010V1
High intensity LED dimming driver evaluation board
based on the L6902
Features
■ Input voltage V
in
= 8 V to 30 Vdc
■ Dimming interface
■ Analog current control
■ Average current control by PWM
Description
Thanks to their high efficiency and reliability,
super high-brightness LEDs are becoming more
and more popular as a subsitute for conventional
light sources. Although LEDs can be supplied
directly from a simple voltage source (like a
battery with resistor), for most applications it is
better to use a switching current source to
achieve not only higher efficiency but also better
light output.
This evaluation board is designed around an
L6902D-based DC-DC converter with dimming
interface. It board implements both of two well
known dimming methods:
■ Analog current control
■ Average current control by PWM
While there is only a single dimming input
connector on the board, it can be used for both
dimming methods.
A signal between 0 and 3.3 V should be used for
analog (peak current) dimming. When the
dimming pin is grounded (0 V), the 350 mA
maximum output current is provided. Likewise,
when 3.3 V is applied to the pin, the current
provided is zero and the LED is off.
The second dimming method implemented on this
board is PWM control of average LED current.
This control requires a digital PWM signal (with an
amplitude of either 3.3 V or 5 V) between the
dimming pin and the ground pin. Varying the duty-
cycle on the board will then change the brightness
of the LED (100% = LED off, and 0% = LED fully
on).
STEVAL-ILL010V1
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