LED lighting circuit design

Design a circuit consisting of a power supply, LEDs, and resistors. The actual components have variations in resistance and Vf, so there will be errors in the LED current.

V
V
ohm

SI prefixes accepted (4k7 / 1M / 10m / 220). Upper-case M = mega, lower-case m = milli

LED current
0.638mA
Max LED Current0.896 mA
min LED current0.304 mA
Advanced — Max voltage, min Volatge, Vf Max and 2 more
V
V
V
V
%

Derived values

Resistor dissipation
1.91 mW
Worst case 3.77 mW
LED dissipation
1.28 mW
Vf × I
Total dissipation
3.19 mW
Vcc × I
Voltage across R
3 V
Vcc − Vf

Worst case 3.77 mW. With 50% derating you need a 7.55 mW rating or better, so a 1/16W (1005 / 0402) chip resistor is enough.

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