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Design >> Analog Design >> who tell me something about the 5V &3.3V
https://designers-guide.org/forum/YaBB.pl?num=1157073578

Message started by hunk on Aug 31^st, 2006, 6:19pm

Title: who tell me something about the 5V &3.3V
Post by hunk on Aug 31^st, 2006, 6:19pm

it is well-known that almost all chip use a supply of 5V or 3.3V, especially for computer's chip. i just only use this but dont know why this is.

can anyone tell me or show some materials related. maybe there are some interesting storys.

Title: Re: who tell me something about the 5V &3.3V
Post by jbdavid on Sep 1^st, 2006, 11:31pm

It has something to do with the oxide thicknesses used in chip design.
But your information is a little out of date, Most chips today use ~1v for core logic and 1.5-3.3v for IO devices
for instance popular foundries do 130nm feature size silicon at 1.0/1.2v core and 2.5/3.3v IO.

for more information you might want to look into the ITRS roadmaps.

Title: Re: who tell me something about the 5V &3.3V
Post by loose-electron on Sep 3^rd, 2006, 1:40pm

There is no "divine voltage" for power supplies on digital circuits.

RTL and discrete ECL of 1960's era was done at 12 and 15V supplies, and then was transferred over to -5.2 supplies (ECL) for integrate (Motorola 10,000 series MECL) and the 7400 seriees of TTL was done mostly for 5V, which allowed enough headroom for bipolar logic.

If I remember correctly 4000 series CMOS started at 5V in order to be plug compatible with 7400 TTL.

From there CMOS transistors started shrinking and the voltages had to reduce to keep the transistors from being burned out. (Vgs of gate oxides, and Vds punchthrough)

Digital power for logic exists at 5V, 3.3, 2.8, 2.5, 1.8, 1.2 and 0.8 volts.

I am probably forgetting a few, but those are the ones immediatly remembered.

Jerry

Title: Re: who tell me something about the 5V &3.3V
Post by hunk on Sep 3^rd, 2006, 6:10pm

thanks very much! i get more knowledge from here. :)