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I need to know the power consumption for a EP4CE55 FPGA during its reset state. I really can't locate this information, but it has to be written somewhere...
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Try the PowerPlay EPE spreadsheet to get an idea (there's a spreadsheet for each device family).
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I intend to hold nCONFIG low until negotiation with the power supply is done, and startup is permitted. Does this seem like a valid way?
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Ideally you should ramp the power supplies up within the timeframe recommended by the data sheet. The soft-start pins on linear and switching regulators can be used to make this happen easily enough. The datasheets generally indicate that if you cannot meet the power-on-reset sequencing requirements, then you should hold nCONFIG low until the supplies are ready.
So yes, your scheme would work, though I would double-check whether it is necessary. For example, if you are providing an option to turn a supply on or off, or to select the I/O voltage, then you could turn all supplies off, program them to their new values, and then turn them on again.
Cheers,
Dave
Honored Contributor
