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Science Forum Index » Electronics - Basics Forum » D82C55AC-2...
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| aleksa... |
 Posted: Tue May 20, 2008 9:06 am |
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I've bought 10 pcs of "82C55" through mail, and received D82C55AC-2.
The problem is that the output high voltage of any pin is not 5V, but
3.8V.
Nothing is connected to the port pins, VCC is 4.85V.
Am I wrong thinking that CMOS chips should have far more than 3.8V on
output pins?
Thanks |
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| JeffM... |
| Posted: Tue May 20, 2008 2:06 pm |
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| Paul E. Schoen... |
| Posted: Tue May 20, 2008 5:59 pm |
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"aleksa" <aleksaZR at (no spam) gmail.com> wrote in message
news:018b7590-87fb-4a29-ba87-1871db7a6c24 at (no spam) w34g2000prm.googlegroups.com...
Quote: I've bought 10 pcs of "82C55" through mail, and received D82C55AC-2.
The problem is that the output high voltage of any pin is not 5V, but
3.8V.
Nothing is connected to the port pins, VCC is 4.85V.
Am I wrong thinking that CMOS chips should have far more than 3.8V on
output pins?
Thanks
I have an old product that used an 8255 to interface to TTL logic, and I
recall some problems when we tried to use CMOS versions. I think we could
fix it by using pullups, but it was easier to get the non-CMOS version. I
don't have the data sheets handy, but I think your parts probably meet
specs. I think the 8255s are actually BICMOS.
Paul |
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