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From: Lizard Blizzard
Subject: Re: Level shifter design
Date: Mon, 30 Sep 2002 11:59:34 -0700
X-Mailer: Mozilla 4.79 [en] (Windows NT 5.0; U)
petrus bitbyter wrote:
> What do you mean by making it yourself? MAX3223 and SP3223 are only IC's you
> can use to build the level shifter you need. You can find all the schematics
> you need on MAXIM's website http://www.maxim-ic.com in the datasheets. You
> may also look for MAX232. It's by far the easiest way. You only need a small
> 5V power supply, the chip and some discrete components like capacitors and
> If you like it more difficult you can use a MC1488 and a MC1489 or their
> equivalents. Look at Texas, Motorola or others for the datasheets. You wil
> need a +5V and a -5V power supply.
> If you do not have the skills to build the circuits mentioned, I advise not
> to try a circuit build with discrete components. You can get an idea of the
> complexity of this circuits by looking at the internals of the 1488/89 in
> their datasheets.
The receiver is simply a transistor with a resistor and diode on the
input to clamp the voltage to ground so that the base goes no more than
-0.6 below 0. The transmitter does nothing more than drive the line.
The same thing can be done with a transistor and resistor. Both Tx and
Rx invert the inputs.
> "Jerome" schreef in bericht
> > Hi,
> > I would like to design and make a level shifter to plug a GPS to a
> > RS232 port.
> > The level on the serial port of the GPS is CMOS (3.3V). SO I was told
> > that a good level shifter would be a MAX 3223 or SP3223.
> > I would like to make the level shifter myself, but I don't know how to
> > do it ( what I need, schema, ....). I have not a lot of information
> > about it.
> > Thanks
> > Jerome
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