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POWERDOWNMODE
1 2 3 4 5 9
10 16
CS
SCLK
SDO
t
d5
t
d6
invalid 数据 Valid 数据
SDO
1 5432 6 10987 131211 161514 1 5432 6 10987 131211 161514
SCLK
设备 全部地
powered-向上
设备 开始
powering 向上
CS
ADS7886
SLAS492–SEPTEMBER2005
ThedeviceenterspowerdownmodeifCSgoeshighanytimeafterthe2ndSCLKfallingedgetobeforethe10th
sclkfallingedge.ongoingconversionstopsandsdogoesto3-stateunderthispowerdownconditionas
showninFigure2.
figure2.enteringpowerdownmode
adummycyclewithcslowformorethan10sclkfallingedgesbringsthedeviceoutofpowerdownmode.为
thedevicetocometothefullypoweredupconditionittakes1µs.cscanbepulledhighanytimeafterthe10th
fallingedgeasshowninFigure3.itisnotnecessarytocontinueuntilthe16thclockifthenextconversionstarts
1µsaftercsgoinglowofthedummycycleandthequiettime(t
q
)conditionismet.
figure3.exitingpowerdownmode
7