[elektro] Miért pont 5V ???

[Xorn]

Meg még egy... :-)))

"Oh that's an easy one to answer.

Criteria number 1 : Base-emittor junctions of a transistor that are
reverse polarised cannot have much more than 6 volts. They start
'leaking' and accumulate time based damage.
Criteria number 2 : fist logic chips were bipolar and had quite a bit
a static current consumption resulting in heat. higher voltage means
more heat...
criteria number 3 : early chip technology used for digital suffered
from scaling problems. they needed quite a bit of distance to 'hold' a
standoff voltage. making chips impractical and expensive ( the cost of
a chip is defined in square millimeters of surface... )

throw that in a heap and you end up with something that works between
3 and 5 volts. At 3 volts the transistors did not switch 'fast' enough
to get nice clean pulses so they settled at 5 volts. All criterias
met."

Best regards,
Andy

2014-05-20 11:52 GMT+02:00 elight at gmail.hu <elight at gmail.hu>:
> Sziasztok,
>
> míg nagy ütemben fogy az ón a gurigáról,
> azon gondolkodom éppen,
>
> miért pont +5V  a legyakrabban alkalmazott feszültség
> a digitális áramköröknél..
> Lehetne mínusz is..
>
> És jó tudom  újabban már szabadon választott ,
> akár lemehet 1,8V-ig..
> De régebben azért  ez volt az álatalános.
> Van ennek talán valamiféle története is?
>
> Üdv István
>
> -----------------------------------------
>           elektro[-flame|-etc]