Subject: Re: Why zener diode can't make at 1.5v/4.5v/5.0v/6.0v/7.5v/9.0v ?
Date: Fri, 27 Dec 2002 21:53:33 +0700
Organization: C.S. Communications Co. Ltd.
References: <3E09BFEC.94F39E36@fanwap.com> <3E0B4339.B5803F40@rica.net>
NNTP-Posting-Date: Fri, 27 Dec 2002 14:53:48 +0000 (UTC)
X-Mailer: Mozilla 4.8 [en] (Windows NT 5.0; U)
I see. Thank you very much.
But I think, sell the value in series is not good for zener diode
and doesn't make sense.
Why they doesn't sell every 0.5V value and/or popular voltage like
3.3v 5v 6v 7.5v 9v 12v - 5%
So technology can't make 1% today ?
Does zener diode use in the imprecise function only ?
John Popelish wrote:
> "KL@*@(" wrote:
> > Why zener diode can't make at
> > 1.5v
> > 4.5v
> > 5.0v
> > 7.5v
> > 9.0v
> > ?
> > What's wrong with the technology ?
> The minimum voltage where the zener reverse breakdown process
> functions is around 2.7 volts. The exact values of zener nominal
> voltages is based on tolerance. For instance, if a zener has a
> nominal voltage of 5.1 volts, and a tolerance of plus or minus 5% (5.1
> *.95=4.845, 5.1*1.05=5.355) then there is no point making any other
> nominal values that have a 5% tolerance that fall within the range of
> 4.845 to 5.355, since the 5.1 volt unit could actually produce a
> reverse breakdown anywhere in that range. This is the same reason
> that resistors of a given tolerance are produced with only certain
> standard values, like 4.7k, 5.1k, 5.6k, etc.
> However, there are integrated circuits that function much like zener
> diodes (called shunt regulators or voltage references), but have the
> capability to have their breakdown voltage adjusted with a trim pot.
> You can set these to whatever voltage you require (within their
> John Popelish