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Changing 5v to 3v logic — Parallax Forums

Changing 5v to 3v logic

ArchiverArchiver Posts: 46,084
edited 2000-05-13 02:27 in General Discussion
Hi,

Does any one know how I can change the stamps 5 volt logic to 3v for a chip.
I need to change about 5 lines.

Is there some kind of buffer I can supply with 3v and will tolerate 5 on an
input, or do I just use resistors?

Thanks
Mike

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2000-05-12 01:11
    Mike,

    If you simply want to input 3V to a Stamp, you don't need to change
    anything, the BS2 reads anything over 1.5 volts as a "1" and
    everything below that as a "0".

    -Chris


    --- In basicstamps@egroups.com, "Michael Licitra" <mikel2@b...> wrote:
    > Hi,
    >
    > Does any one know how I can change the stamps 5 volt logic to 3v
    for a chip.
    > I need to change about 5 lines.
    >
    > Is there some kind of buffer I can supply with 3v and will tolerate
    5 on an
    > input, or do I just use resistors?
    >
    > Thanks
    > Mike
  • ArchiverArchiver Posts: 46,084
    edited 2000-05-12 01:25
    I need to go from the stamp to the 3v device.

    Thanks
    Original Message
    From: "Chris " <c_rosney@y...>
    To: <basicstamps@egroups.com>
    Sent: Thursday, May 11, 2000 8:11 PM
    Subject: [noparse][[/noparse]basicstamps] Re: Changing 5v to 3v logic


    > Mike,
    >
    > If you simply want to input 3V to a Stamp, you don't need to change
    > anything, the BS2 reads anything over 1.5 volts as a "1" and
    > everything below that as a "0".
    >
    > -Chris
    >
    >
    > --- In basicstamps@egroups.com, "Michael Licitra" <mikel2@b...> wrote:
    > > Hi,
    > >
    > > Does any one know how I can change the stamps 5 volt logic to 3v
    > for a chip.
    > > I need to change about 5 lines.
    > >
    > > Is there some kind of buffer I can supply with 3v and will tolerate
    > 5 on an
    > > input, or do I just use resistors?
    > >
    > > Thanks
    > > Mike
    >
    >
    >
    >
    >
  • ArchiverArchiver Posts: 46,084
    edited 2000-05-12 01:33
    Mike,

    If speed is important, take a look at Fairchild's NC7SZ86M. It's an XOR
    gate, usable as a buffer, and it accepts 5V in while it's on a 3V supply.
    Only one gate per (tiny) package, but Fairchild may have something
    equivalent with multiple gates per package...

    >Does any one know how I can change the stamps 5 volt logic to 3v for a chip.
    >I need to change about 5 lines.
    >
    >Is there some kind of buffer I can supply with 3v and will tolerate 5 on an
    >input, or do I just use resistors?

    Mike Hardwick, for Decade Engineering -- <http://www.decadenet.com>
    Manufacturer of the famous BOB-II Serial Video Text Display Module!
  • ArchiverArchiver Posts: 46,084
    edited 2000-05-12 01:37
    You can just use PWM. Read the manual.
    -William
    Original Message
    From: Michael Licitra <mikel2@b...>
    To: <basicstamps@egroups.com>
    Sent: Thursday, May 11, 2000 8:25 PM
    Subject: Re: [noparse][[/noparse]basicstamps] Re: Changing 5v to 3v logic


    > I need to go from the stamp to the 3v device.
    >
    > Thanks
    >
    Original Message
    > From: "Chris " <c_rosney@y...>
    > To: <basicstamps@egroups.com>
    > Sent: Thursday, May 11, 2000 8:11 PM
    > Subject: [noparse][[/noparse]basicstamps] Re: Changing 5v to 3v logic
    >
    >
    > > Mike,
    > >
    > > If you simply want to input 3V to a Stamp, you don't need to change
    > > anything, the BS2 reads anything over 1.5 volts as a "1" and
    > > everything below that as a "0".
    > >
    > > -Chris
    > >
    > >
    > > --- In basicstamps@egroups.com, "Michael Licitra" <mikel2@b...> wrote:
    > > > Hi,
    > > >
    > > > Does any one know how I can change the stamps 5 volt logic to 3v
    > > for a chip.
    > > > I need to change about 5 lines.
    > > >
    > > > Is there some kind of buffer I can supply with 3v and will tolerate
    > > 5 on an
    > > > input, or do I just use resistors?
    > > >
    > > > Thanks
    > > > Mike
    > >
    > >
    > >
    > >
    > >
    >
    >
    >
    >
  • ArchiverArchiver Posts: 46,084
    edited 2000-05-12 13:50
    I don't think he can for this purpose: instead of him reading the manual you
    might have read his message a bit better.

    regards,

    Sandor

    William Cox wrote:

    > You can just use PWM. Read the manual.
    > -William
    > [noparse][[/noparse]snip]
  • ArchiverArchiver Posts: 46,084
    edited 2000-05-12 17:30
    >Does any one know how I can change the stamps 5 volt logic to 3v for a
    chip.
    >I need to change about 5 lines.
    >
    >Is there some kind of buffer I can supply with 3v and will tolerate 5 on
    an
    >input, or do I just use resistors?

    The CD4050 and CD4049 (inverting) are hex CMOS buffers that can accept
    input voltages higher than their power supply. Resistors wouldn't be bad
    either, especially using a couple of sip packages.

    -- Tracy Allen
    Electronically Monitored Ecosystems
    http://www.emesystems.com
  • ArchiverArchiver Posts: 46,084
    edited 2000-05-12 20:23
    Excuse me. Just trying to help.
    -William

    Original Message
    From: Sandor Rabe <sandor.rabe@e...>
    To: <basicstamps@egroups.com>
    Sent: Friday, May 12, 2000 8:50 AM
    Subject: Re: [noparse][[/noparse]basicstamps] Re: Changing 5v to 3v logic


    > I don't think he can for this purpose: instead of him reading the manual
    you
    > might have read his message a bit better.
    >
    > regards,
    >
    > Sandor
    >
    > William Cox wrote:
    >
    > > You can just use PWM. Read the manual.
    > > -William
    > > [noparse][[/noparse]snip]
    >
    >
    >
  • ArchiverArchiver Posts: 46,084
    edited 2000-05-13 02:27
    For outputs I would just use a resistor in series, then a 3v zener in
    parallel.

    Bean, thitt@i...
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