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Altera_Forum
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16 years ago

The IO Standard and Pin Configuration

Dear all: I have some question about the IO standard when doing my design. Could you please help me to resolve that? I use EP3C40F780 as my main processor. And I want to use EPCS...
Altera_Forum's avatar
Altera_Forum
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16 years ago

Powering the nCSO pin at 2.5V should not be a problem. The datasheet for EPCS devices indicate that Vih is 0.6*Vcc so even at 3.3V you only need 2.0 V for a logic high. BTW, you can use 3rd party flash devices in place of the EPCS device and some of these do run at 2.5V.

With regards to the clock; if you are powering the bank at 2.5V, you should provide a 2.5V single-ended clock rather than 3.3V. However, if you are using the clock to drive LVDS transmitters or receivers, you may have to use a differential clock input. I'm not sure about Cyclone III but this was necessary on Stratix IV.

Jake