[Libre-silicon-devel] Pearl River, demo board

Hagen SANKOWSKI hsank at posteo.de
Wed Jul 18 12:34:43 CEST 2018

Hello David.

Well, to connect a LED to a output pad *outside* the chip is quite easy.
The pad should able to drive a current of round about 10..20 mA, with
voltage higher than the LED threshold voltage.

I already thought about an Open Drain output driver, which is quite
useful for driving LEDs even with lower supply voltages than the LED
threshold. Another topic is a bipolar output driver (aka BiCMOS)
https://en.wikipedia.org/wiki/BiCMOS with higher current capabilities.

The other think, we *can not* do, is implementing a LED *on chip*.
The brightness of different colors of LEDs resulting from different
materials, see

And yes, all this thoughts belongs to the documentation / wiki ;-)


On 07/18/2018 11:57 AM, David Lanzendörfer wrote:
> Hi Hagen, hi list
> Cedric and I just talked about the Pearl River test wafer, and I had an 
> inspirational flash:
> We totally should make it possible to hook up LEDs to the output pads of the 
> Pearl River on a PCB, so that we can demonstrate that the pad cell drivers 
> have the capability of driving an LED!
> At the SEG plaza in Shenzhen there are many vendors with demo circuits showing 
> the color and brightness of the LEDs in action.
> We could also make such a demo board in order to demonstrate the multiple 
> different capabilities of the LibreSilicon process.
> Would do you think?
> Cheers
> 	David

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