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Dongle led current consumption

Mumi

This may be a newbie question, but it had puzzled me for a while now.

Looking at the PCA10031's schematics i can see two leds been used.

LD2 i can figure out. Datasheet for the led says between 2 and 2.4 forward voltage.. let us say 2.2... (3.3-2.2)/220R = 5 mA.. fits perfect with the pin's sink-capabilities.

Now LD1.. in the datasheet the min. forward voltage for Green is 2.75V... (3.3-2.75)/680R = 0,81 mA... (the datasheet sates forward current is 2mA).

Are you really using that little current or i'm way of ? I got the part nr. from the BOM

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  • 0

    Hi. You are not mistaken. The values in the schematic are correct. LEDs are amazing! However, if you look closely at the datasheets for both LD1 and 2 you can see that you actually need approximately 10 times more current running through the LEDs in LD2 to reach the same luminosity as in LD1. So I guess the number makes kind of sense.

    Martin

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