Pico Communications E-14 Computer Hardware User Manual


 
E14HardwareReferenceManual www.picocomputing.com PicoComputing,Inc.
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AppendixG
FPGAPerformanceEnhancements
Overview:
Likemostsilicondevices,theFPGAonthePicocanbeoverclockedifpropercoolingtechniquesare
employed.Caremustbetakentoavoidthermalrunaway.
ThermalRunaway:
AsthedietemperatureoftheFPGAincreases,itdrawsmorecurrent.Thisextracurrentgetsturned
intoheat.Ifthermalequilibriumisnotreachedwithpropercooling,theFPGAwilloverheator
overstressthepowersupplies.Inalllabtests,theFPGAcorepowersupplyshutdownbeforetheFPGA
couldbedamagedbyanovertemperaturecondition(althoughthisbehaviorisnotguaranteed).The
maximumFPGAcoretemperatureis150°C.NotethatchipssurroundingtheFPGAwillbedamagedby
temperaturesabove85°C.
HeatSinkPlacement:
TheheatsinkoftheFPGAisinternallyconnectedviathermalgreasetothecaseoftheCardBuscardon
thetopside(serialnumberside).Placingalargeheatsinkontheoutsideofthecasecanallowhigher
performance.
PowerRequirements:
Caremustbetakentokeepcurrentconsumptionunderthe1Amaximumspecifiedbythe3.3V
CardBusstandard.Ifanexternalpowersupplyisavailabletheboardcanbesupplied5.0Vformaximum
power,however,thedigitalinterfaceswillstillcommunicateattheLVTTL3.3Vstandard.
SpeedRatings:
PicoComputingusesallindustrialtemperaturerangepartswhereavailable.Whena‐10industrial
temperaturespeedgradeFPGAiscreated,a‐11commercialspeedgradepartistestedto‐10
performanceratingsattheindustrialtemperaturerange.Picocomputingdoesnotguaranteethat‐10
industrialpartscanbeoperatedat‐11speedswhenkeptbelow85°C.