Computer Hardware User Manual

E‐14HardwareReferenceManual www.picocomputing.com PicoComputing,Inc.

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AppendixG

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FPGAPerformanceEnhancements

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Overview:

Likemostsilicondevices,theFPGAonthePicocanbeoverclockedifpropercoolingtechniquesare

employed.Caremustbetakentoavoidthermalrunaway.

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ThermalRunaway:

AsthedietemperatureoftheFPGAincreases,itdrawsmorecurrent.Thisextracurrentgetsturned

intoheat.Ifthermalequilibriumisnotreachedwithpropercooling,theFPGAwilloverheator

overstressthepowersupplies.Inalllabtests,theFPGAcorepowersupplyshutdownbeforetheFPGA

couldbedamagedbyanovertemperaturecondition(althoughthisbehaviorisnotguaranteed).The

maximumFPGAcoretemperatureis150°C.NotethatchipssurroundingtheFPGAwillbedamagedby

temperaturesabove85°C.

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HeatSinkPlacement:

TheheatsinkoftheFPGAisinternallyconnectedviathermalgreasetothecaseoftheCardBuscardon

thetopside(serialnumberside).Placingalargeheatsinkontheoutsideofthecasecanallowhigher

performance.

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PowerRequirements:

Caremustbetakentokeepcurrentconsumptionunderthe1Amaximumspecifiedbythe3.3V

CardBusstandard.Ifanexternalpowersupplyisavailabletheboardcanbesupplied5.0Vformaximum

power,however,thedigitalinterfaceswillstillcommunicateattheLVTTL3.3Vstandard.

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SpeedRatings:

PicoComputingusesallindustrialtemperaturerangepartswhereavailable.Whena‐10industrial

temperaturespeedgradeFPGAiscreated,a‐11commercialspeedgradepartistestedto‐10

performanceratingsattheindustrialtemperaturerange.Picocomputingdoesnotguaranteethat‐10

industrialpartscanbeoperatedat‐11speedswhenkeptbelow85°C.