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From: email@example.com (Bob Wilson)
Subject: Re: Voltage level translation
Date: Sun, 22 Sep 2002 22:51:01 -0000
Organization: Your Organization
X-Newsreader: WinVN 0.99.9 (Released Version) (x86 32bit)
In article <3D8C8FA4.firstname.lastname@example.org>, email@example.com says...
>I want to take the output of a 3.3v cpld and have it drive various
>target devices that may be 1/1.8/2.5/3.3/5 volts. Can someone
>provide me with a Simple circuit (e.g., 1 transistor + resistors)
>that will do this. I've heard a common-base transistor configuration,
>with some modifications will accomplish this. Also the delay should
>be no more than 10 ns throught the translator.
>All help is greatly appreciated.
Common base topology would be entirely useless. Common emitter is the normal
way to use a transistor as an interface. Not exactly rocket science, since
is is the most common transistor topology and is basically the
first day of an Electronics I course.
But if you are trying for a 10nS max delay, then you can forget about a
simple 1-transistor interface, since the pullup resistor (coupled with
parasitic capacitances) will result in at least 2 orders of magnitude
greater delay on the rising edge.
Many of the votages you are referring to need no interface at all. For
example,2.5 and 3.5 volt logic will interface directly, as will 1.8 and
2.5V. Even 1.8V and 3.5V logic will interface directly under many
Sounds like you may need a bit of basic electronics under your belt before
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