Programmable Devices
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Power Delivery Network tool says I need very few capacitors.

BVola
Principiante
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Running PDN for Cyclone IV results show only 4 capacitors required, based on results from EPE. I can even change current to 1 amp and it still only requires 5 caps. Is this right? PDN attached.

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8 Respostas
ak6dn
Colaborador valorado III
1.720 Visualizações

Your power rail currents range from 10mA(min) to 40mA(max) in the spreadsheet.These are extraordinarily low numbers and very likely incorrect.

BVola
Principiante
1.720 Visualizações

Everything came right from the power estimator; I was also a little surprised at how low the core current was. I revisited my power calculation, and I changed the I/O load capacitance. It's not clear if the load capacitance column in the power estimator is TOTAL capacitance or capacitance-per-pin. I initially assumed that it was per pin. I changed it to total, which gave me 1300pF (130 pins), which caused the current to jump to about 900 mA. Still, changing that number had very little effect on number of capacitors. And, as I mentioned, I can just arbitrarily put high current values into the PDN tool and still get very few capacitors.

 

(Full disclosure: I cheated and lumped all my I/O into one module; that shouldn't make a difference).

ak6dn
Colaborador valorado III
1.720 Visualizações

You have no entry for your core clock frequency. Power to the core will vary dramatically with frequency and % utilization.

Same for I/O power. Static load is not as much a determining factor as is dynamic I/O switching frequency.

BVola
Principiante
1.720 Visualizações

The power estimator uses the clock frequency to calculate dynamic power, so that's already accounted for. Further, the Core Clock field is "N/A", and can't be changed (the popup note indicates that you need to be in "custom mode" to enter that. Not even sure HOW to enter custom mode).

ak6dn
Colaborador valorado III
1.720 Visualizações

Well in that case I don't believe the spreadsheet at all. A 1.2V Vcore at 20mA and a recommended 5ohm target impedance for the power rail are completely unrealistic values. I don't know what inputs you fed into Quartus to generate this spreadsheet but I would go back to the source. Something in your core and I/O clock setup is not correct.

SreekumarR_G_Intel
Funcionário
1.720 Visualizações

can i know you guys facing still issue the same issue ?

BVola
Principiante
1.720 Visualizações

Nothing has changed. Do I trust the power estimator? Do I trust the PDN tool?

YuanLi_S_Intel
Funcionário
1.501 Visualizações

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