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Altera_Forum
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14 years ago

Cyclone IV/EPCS config voltages

When using a Cyclone IV GX device with an Altera EPCS128 serial config flash (in AS mode), is there a preferred voltage for both the flash and the VCCIO of the configuration bank? Looking through the...
Altera_Forum's avatar
Altera_Forum
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14 years ago

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should I just trust the dev board schematic?

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Never trust the evaluation board schematics, trust your own engineering judgement.

Want more proof of this statement; look on the Cyclone IV Transceiver Starter Kit Embedded USB Blaster circuit on p12. The MAX II device is connected to the FTDI EEPROM USB_EECS/EECK/EEDATA signals. The EEPROM is powered from 5V, so those signals are 5V logic levels. I bet if you measure those signals on the MAX II which is powered from 2.5V, you'll find they are also violating the MAX II voltage specification.

The same goes for the 5V LCD module. Try reading from the LCD and I'm sure you'll see close to 5V levels (many of the Altera boards have this design error). That will violate the Cyclone IV GX voltage spec.

Cheers,

Dave