[elektro] Miért pont 5V ???

[Pataki István]

Talán ezek a szempontok lehettek valóban a legfontosabbak.
pi


----- Original Message ----- 
From: "Xorn" <toth.endre at gmail.com>
To: <elektro at tesla.hu>
Sent: Tuesday, May 20, 2014 12:49 PM
Subject: Re: [elektro] Miért pont 5V ???


> 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]
>
> -----------------------------------------
>          elektro[-flame|-etc]