[sdiy] old datasheet "schematics" vs modern "simplified schematics"

[rsdio at audiobanshee.com]

My hunch is that the number of transistors has increased over the years to the point where they simply cannot show the entire circuit.

I still see many chip data sheets with input circuits and output circuits detailed, so that you can interface to them properly, but the internals are hidden. It's also common to delete transistors used for current sources and just show them as a functional block.

I believe you'd find that even the old chips didn't show every detail. For example, when they show a resistor, it's not really a resistor but some kind of silicon equivalent. I doubt they ever showed every last detail. Besides, a lot of the performance depends upon the physical dimensions of the transistors inside the wafer, and you won't see that on the circuit inside the chip diagram.

Any particularly good examples that you'd like to point out? Do they really have precise values for every component inside?

Brian Willoughby


On Jul 8, 2014, at 7:26 AM, Dan Snazelle wrote:
> ive been looking into some old chips for BJT design ideas
> 
> mostly fairchild and RCA
> 
> one interesting thing
> (maybe due to the simpler nature of chips then OR because of a different kind of marketing attitude)  it seems they used to publish the full circuit inside that was inside the chip.
> 
> 
> now i may be wrong about this
> but there is a key grammatical difference in old databooks vs. newer ones
> 
> " schematic" vs " simplified schematic"
> 
> one implies that you are seeing a working circuit
> 
> 
> the other that it is missing much
> 
> 
> just wondering if anyone knows why this changed?