Datasheet

BCR420U / BCR421U
Application hints
Datasheet 23 Revision 2.0, 2012-05-04
4 Application hints
Figure 4-1 Application Circuit: Enabling / PWM by Micro Controller
Figure 4-2 Application Circuit: Enabling by Connecting to
V
S
Application hints
BCR420U / BCR421U serve as an easy to use constant current sources for LEDs. In stand alone application an
external resistor can be connected to adjust the current from 10 mA to 250 mA.
R
ext
can be determined by using
Figure 3-5 or Figure 3-15. Connecting a low tolerance resistor
R
ext
will improve the overall accuracy of the current
sense resistance formed by the parallel connection of
R
int
and R
ext
leading to an improved current accuracy. Please
take into account that the resulting output currents will be slightly lower due to the self heating of the component
and the negative thermal coefficient.
Please visit our web site www.infineon.com/lowcostleddriver for application notes and for up-to-date
application information.
EN OUT
R
ext
GND
+V
S
2,3,51
I
out
I
EN
BCR421 U
µC
V
drop
6
4
R
ext
(optional )
EN OUT
R
ext
GND
+V
S
V
drop
2,3 ,51
6
4
I
out
I
EN
BCR420 U
R
ext
(optional )