Flicker LED : weekend die-shot

Some might have seen candle flicker LED - their brightness is modulated randomly to mimic real candle. It is achieved by using digital die copackaged with red LED die in standard 5mm transparent case.



This design is apparently using phase difference between 2 RC oscillators as source of random data. There are multiple designs in the wild, some other apparently based on LFSR with single oscillator. More on the topic: siliconpr0n.org, cpldcpu.wordpress.com, hackaday.com.

Die size 580x476 µm, 3µm technology.

Thanks for this interesting chip to ASIP department of Gomel State University.

After metalization etch: