Datasheet BCR401R (Infineon) - 6

BCR401R Standard Application Circuit: Application Circuit:
supply voltages >18V + V s B C R 4 0 1 R Vsupply 3 R e x t V d r o p
IOUT + IDRIVER
LEDs 4 Rsense BCR401R (optional) BCR402R Vs Rext 1 2 I s I o u t GND Iout
IDRIVER IOUT
LEDs
Application hints
BCR401R serves as an easy to use constant current source for LEDs. In stand alone application an external resistor can be connected to adjust the current from 10 mA to 60 mA. Rext can be determined by using the diagram 'Output current versus external resistor', or by refering to diagram 'Output current versus reference voltage'. Look for your desired output current on the y axis and read out the corresponding Vdrop. Calculate Rext: Rext = Vdrop / (Iout -(Vdrop/Rint)) 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 for application notes: www.infineon.com/lowcostleddriver • AN066 explains the basic concept • AN077 gives hints to thermal design • AN159 provides information how to add a power transistor to increase the output current 2009-11-13 6