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Altera_Forum
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16 years ago

VCCIO EPM7128SLC84-15 and 5 Volt outputs: HELP!

I'm using a MAX EPM7128SLC84-15 and need 5V logic outputs. So, the CPLD is wired with all VCC=5V and all the VCCIO = 5V too. Yet the outputs show 3.3V on the 'scope. I believed the Data Sheet page...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

@FvM: Later ...

Yes, that did it. Many thanks. The data sheet (pages 20/21) is confusing on this point. My measurements suggest that when in VCCIO = 5V mode, the outputs are actively pulled down to 0V and actively pulled up to 3.3V. Above 3.3V the outputs are open_drain. So your pull up helps you on upwards to 5V, albeit slowly. Curious design ...

BTW, the hardware is located in Bochum. Small world! Email me if you're interested in a visit (Sternwarte). [Can't email you - too few posts].