Hacker News Reader

Comment by adhoc_slime | Hacker News Reader

My brain went right to search for 2 terms I want everyone to get correct.. still no definitive source to search for the meaning of VCC and VDD. I still see people get this wrong _all the time_.

View on HN

Precisely how do you define definitive so that we might better understand what you assert to be wrong?

My naive intuition suspects he knows, so here's a contrarian curveball pulled directly out of JEDEC JESD88 Dictionary of Terms for Solid-State Technology[1] to consider (my emphasis):

> drain power voltage (VDD): The primary power voltage on MOS devices that require a potential that differs from the normal system logic voltage. The term VDD is used interchangeably with VCC on devices that use 5‑V supplies.

[1] https://www.jedec.org/standards-documents/dictionary/terms/d...

I think this WP article is rather illuminating:

https://en.m.wikipedia.org/wiki/IC_power-supply_pin

That's because they get the meaning from the environment (i.e. datasheets, schematics). And writing a good datasheet is hard and the companies who did this are mostly gone ( Hello Motorola).

Collector and Drain, I thought?

with a stutter? what are the repeated letters for, redundancy?

The repeated letters are to say "not necessarily the collector of _this_ transistor (which may be, for instance, the bottom of a push-pull pair), but the collector of the most-collector-ward transistor".

Explained here: https://en.wikipedia.org/wiki/IC_power-supply_pin

Reply on news.ycombinator.com