PR4401 Datasheet, PDF (9/12 Pages) List of Unclassifed Manufacturers – 0.9V Boost Driver for White LEDs PR4401/4402 Requires Only One External Component

LED DRIVER PR4401/PR4402
Connecting two LEDs in series
It is possible to operate PR4401 and PR4402 with two LEDs in series at the output.
However, while the peak output current is nearly independent of the output load, the mean
output current with two LEDs in series is reduced to half the current with one LED. In
addition, at high output voltages the efficiency drops significantly, depending on operating
conditions, and current pulses become shorter and sharper.
Therefore, although possible and useful in some cases, this operation mode is not
recommended for general applications and not specified further.
Using red, green or yellow LEDs
Although PR4401/PR4402 is optimized for operation with white or blue LEDs, it will usually
also work with red, green or yellow LEDs, with the following restrictions:
a) The LED must build up a sufficient forward voltage to trigger PR4401/PR4402. Due to
the internal resistance of the LED, this condition is usually met. However, no guarantee
can be assumed for proper operation under all conditions, and you need to qualify the
system yourself
b) Due to the different forward voltage level and internal resistance of colored LEDs, the
timing is different, and mean currents are mostly lower than for white LEDs. Also other
parameters may deviate from this data sheet.
© PREMA Semiconductor GmbH 2006-2008
Page 9/12
Rev 0908