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5.5.2MXI2(27-MHz)Oscillator(optionaloscillator)
Crystal
27MHz
C1 C2
MXI2
MXO2 V
SS_MX2
L1
V
DDA_PLL2
V
SSA_PLL2
0.1 F
1 F
C
L
C
1
C
2
(C
1
C
2
)
TMS320DM355
DigitalMediaSystem-on-Chip(DMSoC)
SPRS463A–SEPTEMBER2007–REVISEDSEPTEMBER2007
Table5-3.SwitchingCharacteristicsOverRecommendedOperatingConditionsfor24-MHzSystem
Oscillator
PARAMETERMINTYPMAXUNIT
Start-uptime(frompowerupuntiloscillatingatstablefrequency)4ms
Oscillationfrequency24or36MHz
ESR60Ω
Frequencystability+/-50ppm
TheMXI2(27MHz)oscillatorprovidesanoptionalreferenceclockforthe'sVPSSmodule.Theon-chip
oscillatorrequiresanexternal27-MHzcrystalconnectedacrosstheMXI2andMXO2pins,alongwithtwo
loadcapacitors,asshowninFigure5-6.Theexternalcrystalloadcapacitorsmustbeconnectedonlyto
the27-MHzoscillatorgroundpin(V
SS_MX2
).Donotconnecttoboardground(V
SS
).Also,thePLLpower
pin(V
DDA_PLL2
)shouldbeconnectedtothepowersupplythroughaferritebead,L1intheexamplecircuit
showninFigure5-6.
Figure5-6.MXI2(27-MHz)SystemOscillator
Theloadcapacitors,C1andC2,shouldbechosensuchthattheequationissatisfied(typicalvaluesare
C1=C2=10pF).CLintheequationistheloadspecifiedbythecrystalmanufacturer.Alldiscrete
componentsusedtoimplementtheoscillatorcircuitshouldbeplacedascloseaspossibletothe
associatedoscillatorpins(MXIandMXO)andtotheV
SS_MX2
pin.
Table5-4.SwitchingCharacteristicsOverRecommendedOperatingConditionsfor27-MHzSystem
Oscillator
PARAMETERMINTYPMAXUNIT
Start-uptime(frompowerupuntiloscillatingatstablefrequency)4ms
Oscillationfrequency27MHz
ESR60Ω
Frequencystability+/-50ppm
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