Because they aren't. Someone didn't say "we'll take that comparator and that flip flop and put it into a single package". They figured out what was needed, and then proceeded to work out the circuit.
You could probably make a 555 from any comparator that worked off a single supply voltage going up to +12v, and a CMOS flip flop. If that's what you are trying to do. Might not work perfectly, but the concept is there.
Michael
=46ound these:
Also, LTspice's Yahoo group library includes Jim Thompson's CMOS version, but I don't think anyone has laid out a nice looking schematic for it -- just the .subckt model.
Jon
This is the almost-correct internal schematic:
All the internal functions are done with NPN and PNP transistors. Q1...Q8 make one comparator, and Q10...Q15 is the other.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
As I reported 12 hours ago...
Date: Mon, 13 Aug 2012 08:01:05 -0700 Message-ID: ...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
The functional blocks inside integrated circuits don't have part numbers, they are just collections of bespoke components, components that were designed specifically for that application and also don't have part numbers.
In integrated circuit design it costs no more to use a bespoke part than it does to use a copy of an existing discrete part.
-- ?? 100% natural --- Posted via news://freenews.netfront.net/ - Complaints to news@netfront.net
-- The correct one is on page 11-4 of Hans Camenzind's book, "Designing Analog Chips", which can be downloaded for free at: www.designinganalogchips.com
No, they're not. They're made from transistors that form part of the monolithic silicon slab that is the IC itself.
Your question has no meaning.
LTspice has an "educational", example, circuit, comprising the internals of the 555. It actually works. Get LTspice (free), and study it.
--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.