Datasheet

BCR401U
Application hints
Datasheet 16 Revision 2.0, 2012-04-12
4 Application hints
Figure 4-1 Application Circuit: Stand alone current source
Figure 4-2 Application Circuit: Boost mode current source with external power transistor
Application hints
BCR401U serves as an easy to use constant current source for LEDs. In stand alone application an external
resistor
R
ext
can be connected to adjust the current between 10 mA and 65 mA. R
ext
can be determined by using
Figure 3-8. 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.
In boost mode configuration the LED current can be extended to drive high power LEDs. Please visit our web site
www.infineon.com/lowcostleddriver for detailed application notes.
GND OUT
+V
S
V
drop
2,3,51
I
out
I
S
R
ext
V
S
6
4
R
ext
(optional )
GND OUT
+V
S
V
drop
2,3,51
I
out
I
S
R
ext
V
S
6
4
I
LED
R
1
R
2
R
ext
(optional )