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Altera_Forum
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18 years ago

Cyclone II I/O Output at Power Up!

Using a EP2C8F256C6 and found that during power up there is a 3.3V pulse coming out from the I/O pins. Pulse lasts for ~10ms. As I understand, during power up, pins should be tri-stated but I'...
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Altera_Forum
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18 years ago

All IO Pins of an unprogrammed device should be Tri-stated with a weak pull up. (cf. Cyclone II Handbook - Feb 08 - p. 1-3) So if you do not have a pull down at the pins you will see the pins go up to 3.3V.

The pull up values are given in Table 5-3 of http://www.altera.com/literature/hb/cyc2/cyc2_cii51005.pdf - there is also a suggested value for a pull down resistor in there.

Regards,

Lokla