EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: amaschas on March 03, 2020, 11:49:24 pm
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Hi! So I've been working on a project that involves specific wavelengths of red, green and blue LEDs, and for my project I chose the Luxeon 2835 color line, mostly because they're relatively efficient and come in the wavelengths I needed. However, the documentation of the anode and cathode for this line of LEDs seems to differ depending on what datasheet I look at. On the luxeon site, the datasheet (https://www.lumileds.com/uploads/603/DS216-luxeon-2835-line-datasheet-pdf (https://www.lumileds.com/uploads/603/DS216-luxeon-2835-line-datasheet-pdf)) for the overall line of Luxeon 2835 LEDs and the application brief (https://www.lumileds.com/uploads/660/AB216-pdf (https://www.lumileds.com/uploads/660/AB216-pdf)) both show the anode as the smaller pad and the cathode as the larger pad. They also indicate that the cathode is marked by an inset on the upper side of the LED. However, the datasheet for the color line that I'm using indicates the opposite (https://www.mouser.com/datasheet/2/602/DS236-luxeon-2835-color-line-datasheet-1596094.pdf (https://www.mouser.com/datasheet/2/602/DS236-luxeon-2835-color-line-datasheet-1596094.pdf)). The anode is the larger pad, and the same inset on the top of the LED indicates the anode. My testing on the LEDs I received indicates that the anode is in fact the larger pad, though that cost me a few LEDs since I was following the datasheet for the overall line.
Is it unusual that specifications for LEDs within the same line would vary so much? The application brief for the 2835 line even goes into detail about how the cathode pad should be larger to help with thermal management, yet in the color line the anode is larger. I guess I'm wondering if I'm missing something fundamental here, or if this is just an odd choice of documentation?