HITEC PMAC 3000 - Sensor Connection; Power Connection; Internal Batteries

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PMAC 3000 Page20
SensorConnection
ThePMAC3000hasa singlestraingagefullbridgesensorinput.SeeFigure1.Thesensorinput
rangeisfactorysetto+/‐4.5mV/Vnominal.Minimumbridgeimpedanceis120ohms.Maximum
bridge impedance is 2000 ohms.Bridgeimpedancesgreater than 2000 ohmsmay trigger the
CheckSensorwarning,meaningthatthePMAC3000doesnotsensethesensorpresent.Inthis
case, a parallel resistor across the excitation  leads can be used to bring the impedance under
2000ohms.A2k10%(orbetter)1/8W(orhigher)resistorsuffices.Thisparallelresistor,when
wiredacrosstheexcitationinsidethe15pinconnectorshell,willnotaffectthesensoroperation.
SeeFigure20forsensorwiring.Thesensoritselfusespins1‐5.Theoptionalquadratureencoder
usespins5‐9.Notethattheshieldforthesensorandencoderbothconnecttopin5.Choose
cable that keeps the sensor wires and encoder wires each grouped in their own shield.The
remainingpinsarereservedforautoID.
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Figure20–SensorWiring
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PowerConnection
ThePMAC3000isintendedtoruneitherontheinternalLiIonbatteries,orthesupplied12VDC
ACadapter.Thesuppliedpowersupplywillchargetheinternalbatteriesasrequired,shutting
downthechargewhenthebatteryissufficientlycharged.LEDindicatorsontherearofthePMAC
3000show
thechargestatus.SeeFigure1.Afullchargetypicallytakesfrom2to3hours.
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InternalBatteries
ThePMAC3000hasarechargeableLi‐Ionbatterypackforthemainbattery.Thebackupbattery,
whichpowerstheclockandinternalnon‐volatile RAM,isa3Vlithiumbattery.Bothbatteriesare
solderedtothePCBandarenotuserserviceable.Li‐Ionbatteriesareverysensitivetohow
they
arecharged.Failuretochargethemcorrectlymaycausethemtoexplodeorotherwiseburnup.
ThechargecircuitinthePMAC3000wasdesignedtochargetheinternalLi‐Ionpa ckbasedon