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

From: Sam Saprunoff (sams2@telusplanet.net)
Date: Thu Jan 27 2000 - 10:49:13 EST


Hi Tom,

Thanks for your reply! Yes, it is surprising that there is not a definitive answer within the specs... Further, I have also forwarded a message to the Motorola 683xx list to see if one of the FAEs will answer. If I find out a definitive answer from Motorola, I will post it to the list and to yourself.

Cheers,

Sam

Sam Saprunoff
sams2@telusplanet.net

  ----- Original Message -----
  From: Tom Walsh
  To: ucsimm@uClinux.com
  Sent: Wednesday, January 26, 2000 5:08 PM
  Subject: Re: [uCsimm] Are the uCsimm I/O pins 5V Tolerant?

  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..."
    

This message resent by the ucsimm@uclinux.com list server http://www.uClinux.com/



This archive was generated by hypermail 2b30 : Sun Apr 07 2002 - 00:01:34 EST