I read an interview with the original inventor of the 555.
He was actually embarrassed at its crudeness, and would have done it very differently at the later date.
I guess there was an attempt at an updated version, but it didn't sell.
He was actually embarrassed at its crudeness, and would have done it very differently at the later date.
I guess there was an attempt at an updated version, but it didn't sell.
> The thing is that this is not a good design (the 555). I had a few years of experience, I’d say about five years, but I had no teacher, and I had to learn it by myself.
> You know it was really the beginning of design, so looking at it now, I would say “I wouldn’t do it like that again”. But nobody has actually changed it - it is still the same. They have shrunk it, they shrunk the dimensions. It was a 10 micrometer design, that was the standard size. You could make it in four (micrometers) now. This is more die per wafer, but nobody has changed the arrangement or the schematic.
> As a timer, you know, you trigger it and it runs for a certain time, it is very good. It has a temperature coefficient of like 23 parts per million. Over a large temperature range, that’s like .1 %. Its very stable. In free running mode, as an oscillator, its not so good, about 150 parts per million. And that you could improve down to about 10 ppm. So you could make an improved product. I’m amazed and stunned that in 30 years, somebody hasn’t looked at the schematic and said, “I can make this better”, so for the same area and same cost, and then they have a better product. Nobody has done that.
[1] http://www.semiconductormuseum.com/Transistors/LectureHall/C...
I enjoyed reading the interview. Besides this snippet, he talked about how modern design differs from back when he made the 555. It's always super impressive to me when someone keeps up with their craft through such huge technological changes.
http://www.designinganalogchips.com/_count/designinganalogch...
In one of the later chapters he introduces an updated NE555 design.
Like the 741 op amp its one of those inferior yet friendly teaching tools used heavily in academia.