www.德州仪器.com
reverseinput-outputvoltage
V
输出
V
在
V
输出
V
在
肖特基
LP2981
LP2981
100-maultra-lowdropoutregulator
WITHSHUTDOWN
SLVS521C–JULY2004–REVISEDAUGUST2005
applicationinformation(持续)
aninherentdiodeispresentacrossthepnppasselementofthelp2981.
withtheanodeconnectedtotheoutput,thisdiodeisreversebiasedduringnormaloperation,sincetheinput
voltageishigherthantheoutput.不管怎样,iftheoutputispulledonev
是
higherthantheinput,oriftheinputis
abruptlysteppedbelowtheoutput,thisdiodeisforwardbiasedandcancauseaparasiticsilicon-控制
整流器(scr)tolatch,resultingincurrentflowingfromtheoutputtotheinput(valuesinexcessof100macan
causedamage).因此,topreventpossibledamagetotheregulatorinanyapplicationwheretheoutputmaybe
pulledabovetheinput,anexternalschottkydiodemustbeconnectedbetweentheoutputandinput.withthe
anodeonoutput,thisschottkylimitsthereversevoltageacrosstheoutputandinputpinsto
∼
0.3v,阻止
theregulator'sinternaldiodefromforwardbiasing.
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