Re: Schottky (was:CIA Serial Registers on C128)

From: Hársfalvi Levente (levente_at_terrasoft.hu)
Date: 2002-02-27 09:03:48

Hi!,


ruud.baltissen@abp.nl wrote:
> ...
> The cathode (the black line at the top of the triangle) is marked as a black
> band around the diode (silver when diode is black itself). For speed reasons
> you better can use so-called Scottky-diodes (spelling ??).

No, the 1N4148 is fast enough for sure. The Schottky (BAT85 for example)
is used because of its small drop-out voltage (about 1/3 of the normal
silicon diodes). When using a silicon diode like above (in series with
some digital line), the 'low' logical level will rise above 0.6v. The
Schottky will only lift it up by 0.2v.

BTW, the XE1541 has Schottky diodes too, because of the same reason.


Best regards,


L.

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