Data Brief
For further information contact your local STMicroelectronics sales office.
March 2008 Rev 1 1/4
4
STEVAL-ILL008V1
LED flashlight evaluation board based on the L6920DA
Features
■ High efficiency step-up converter
■ Powered from two cell batteries
■ Output voltage V
out
= 3.5 V
■ Minimum operating input voltage V
in
= 1 V
Description
White LEDs are gaining popularity as sources of
illumination due to their high efficiency and
reliability.
Typical forward voltage drop across a white LED
is approximately 3.5 V. When these LEDs are
powered from a single or two cell batteries, a
boost converter is needed to boost the voltage to
drive the LEDs.
This evaluation board, based on the L6920DA,
implements a high efficiency step-up converter
which requires very few passive components to
perform the conversion from the battery voltage to
the selected output voltage or current. Startup is
guaranteed at 1 V and the device operates down
to 0.6 V. The device has a very low quiescent
current of only 10 µA.
An internal synchronous rectifier is implemented
with a 120 mΩ P-channel MOSFET, replacing the
conventional boost diode, to improve efficiency.
This also could reduce the cost of the application
since no external diode required.
STEVAL-ILL008V1
www.st.com
