Filter
Top Products
www.ti.com
PRODUCT PREVIEW
5.16PulseWidthModulator(PWM)
5.16.1PWM0/1/2/3Electrical/TimingData
PWM0/1/2/3
1
3
3
2
TMS320DM355
DigitalMediaSystem-on-Chip(DMSoC)
SPRS463A–SEPTEMBER2007–REVISEDSEPTEMBER2007
TheDM355contains4separatePulseWidthModulator(PWM)modules.Thepulsewidthmodulator
(PWM)featureisverycommoninembeddedsystems.Itprovidesawaytogenerateapulseperiodic
waveformformotorcontrolorcanactasadigital-to-analogconverterwithsomeexternalcomponents.
ThisPWMperipheralisbasicallyatimerwithaperiodcounterandafirst-phasedurationcomparator,
wherebitwidthoftheperiodandfirst-phasedurationarebothprogrammable.ThePulseWidthModulator
(PWM)modulessupportthefollowingfeatures:
•32-bitperiodcounter
•32-bitfirst-phasedurationcounter
•8-bitrepeatcountforone-shotoperation.One-shotoperationwillproduceN+1periodsofthe
waveform,whereNistherepeatcountervalue.
•Configurabletooperateineitherone-shotorcontinuousmode
•Bufferedperiodandfirst-phasedurationregisters
•One-shotoperationtriggerablebyhardwareeventswithprogrammableedgetransitions.(low-to-highor
high-to-low).
•One-shotoperationtriggerablebytheCCDVSYNCoutputofthevideoprocessingsubsystem(VPSS),
whichallowsanyofthePWMinstantiationstobeusedasaCCDtimer.ThisallowstheDM355module
tosupportthefunctionsprovidedbytheDM320CCDtimerfeature(generatingstrobeandshutter
signals).
•One-shotoperationgeneratesN+1periodsofwaveform,Nbeingtherepeatcountregistervalue
•ConfigurablePWMoutputpininactivestate
•InterruptandEDMAsynchronizationevents
Table5-46.SwitchingCharacteristicsOverRecommendedOperatingConditionsforPWM0/1/2/3
Outputs
(1)
(seeFigure5-47andFigure5-48)
DM355
NO.PARAMETERUNIT
MINMAX
1t
w(PWMH)
Pulseduration,PWMxhighPns
2t
w(PWML)
Pulseduration,PWMxlowPns
3t
t(PWM)
Transitiontime,PWMx.05Pns
4t
d(CCDC-PWMV)
Delaytime,CCDC(VD)triggereventtoPWMxvalid10ns
(1)P=MXI1/CLKINcycletimeinns.Forexample,whenMXI1/CLKINfrequencyis24MHzuseP=41.6ns.
Figure5-47.PWMOutputTiming
SubmitDocumentationFeedbackPeripheralInformationandElectricalSpecifications145