Re: [uCsimm] Are the uCsimm I/O pins 5V Tolerant?

From: Tom Walsh (tom@mytoys.com)
Date: Wed Jan 26 2000 - 20:49:11 EST


Tom Walsh wrote:

    I miskeyed, use the 74LVX family

TomW

> Sam Saprunoff wrote:
>
>> Hello everyone,
>>
>> I was curious... Are the uCsimm I/O pins 5V Tolerant? I have been
>> unable to
>> verify this from searching through the uCsimm manual (Vdd -0.5 to
>> +4.0,
>> Vin -0.5 to +7.0), nor the Motorola MC68EZ328 users manual (Vdd/Vin
>> -0.3 to
>> +7.0).
>>
>> Thanks in advance!
>>
>
> No, they are not. You must use a logic family such as the 74LV which
> also provides for voltage level shifting. Nothing in the 68EZ328 User
> Manual says anything either way regarding the voltages on the i/o (and
> other) pins, as it usually happens, attaching a voltage higher than
> that of the the specified supply of A processor, generally results in
> damage to the pin through long term use.
>
> I would certainly welcome being wrong on this issue, but as yet, I
> have read no definitive documentation that specifically addresses the
> issue of TTL family interfacing. Rule of thumb? If they don't spec
> it, don't believe it!
>
> Regards,
>
>
> TomW
>
>
>
> --
> Tom Walsh - WN3L - Embedded Systems Consultant - tom over_at mytoys(.)com
> 'www.mytoys.com', 'www.openhardware.net', 'www.cyberiansoftware.com'
> "Windows? No thanks, I have work to do..."
>
>

--
Tom Walsh - WN3L - Embedded Systems Consultant - tom over_at mytoys(.)com
'www.mytoys.com', 'www.openhardware.net', 'www.cyberiansoftware.com'
"Windows? No thanks, I have work to do..."

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