參數資料
型號： LTC4266CUHF#PBF
廠商： LINEAR TECHNOLOGY CORP
元件分類： 電源管理
英文描述： POWER SUPPLY MANAGEMENT CKT, PQCC38
封裝： 5 X 7 MM, LEAD FREE, PLASTIC, MO-220WHKD, QFN-38
文件頁數： 10/30頁
文件大小： 414K
代理商： LTC4266CUHF#PBF
LTC4266
4266fa
ApplicAtions inForMAtion
4-PointDetection
TheLTC4266usesa4-pointdetectionmethodtodiscover
PDs.False-positivedetectionsareminimizedbycheck-
ingforsignatureresistancewithbothforced-currentand
forced-voltagemeasurements.Initially,twotestcurrents
areforcedontotheport(viatheOUTnpin)andtheresulting
voltagesaremeasured.Thedetectioncircuitrysubtracts
thetwoV-Ipointstodeterminetheresistiveslopewhile
removingoffsetcausedbyseriesdiodesorleakageat
theport(seeFigure12).Iftheforced-currentdetection
yieldsavalidsignatureresistance,twotestvoltagesare
thenforcedontotheportandtheresultingcurrentsare
measured and subtracted. Both methods must report
validresistancesfortheporttoreportavaliddetection.
PDsignatureresistancesbetween17kand29k(typically)
aredetectedasvalidandreportedasDetectGoodinthe
correspondingPortStatusregister.Valuesoutsidethis
range,includingopenandshortcircuits,arealsoreported.
Iftheportmeasureslessthan1Vatthefirstforced-current
test,thedetectioncyclewillabortandShortCircuitwillbe
reported.Table2showsthepossibledetectionresults.
Table2.DetectionStatus
MEASUREDPDSIGNATURE
DETECTIONRESULT
IncompleteorNotYetTested
DetectStatusUnknown
<2.4k
ShortCircuit
Capacitance>2.7F
CPDtooHigh
2.4k<RPD<17k
RSIGtooLow
17k<RPD<29k
DetectGood
>29k
RSIGtooHigh
>50k
OpenCircuit
Voltage>10V
PortVoltageOutsideDetectRange
OperatingModes
Theport’soperatingmodedetermineswhentheLTC4266
runs a detection cycle. In manual mode, the port will
idleuntilthehostordersadetectcycle.Itwillthenrun
detection,reporttheresults,andreturntoidletowaitfor
anothercommand.
Insemi-automode,theLTC4266autonomouslypollsa
portforPDs,butitwillnotapplypoweruntilcommanded
todosobythehost.Theportstatusregisterisupdated
attheendofeachdetectioncycle.Ifavalidsignature
resistanceisdetectedandclassificationisenabled,the
portwillclassifythePDandreportthatresultaswell.
Theportwillthenwaitforatleast100ms(or2secondsif
midspanmodeisenabled),andwillrepeatthedetection
cycletoensurethatthedataintheportstatusregisteris
up-to-date.
Iftheportisinsemi-automodeandhighpoweropera-
tionisenabled,theportwillnotturnoninresponseto
apower-oncommandunlessthecurrentdetectresultis
detectgood.AnyotherdetectresultwillgenerateatSTART
faultifapower-oncommandisreceived.Iftheportisnot
inhighpowermode,itwillignorethedetectionresultand
applypowerwhencommanded,maintainingbackwards
compatibilitywiththeLTC4259A.
Behaviorinautomodeissimilartosemi-auto;however,
afterdetectgoodisreportedandtheportisclassified(if
classificationisenabled),itisautomaticallypoweredon
withoutfurtherintervention.Instandalonemode,theICUT
andILIMthresholdsareautomaticallysetinautomode;
see the power-on Reset and the AUTO Pin section for
moreinformation.
Thesignaturedetectioncircuitryisdisabledwhentheport
isinitiallypoweredupwiththeAUTOpinlow,inshutdown
mode, or when the corresponding detect enable bit is
cleared.
DetectionofLegacyPDs
Proprietary PDs that predate the original IEEE 802.3af
standardarecommonlyreferredtotodayaslegacyde-
vices.OnetypeoflegacyPDusesalargecommonmode
Figure12.PDDetection
FIRST
DETECTION
POINT
SECOND
DETECTION
POINT
VALID PD
25k SLOPE
275
165
CURRENT
(A)
0V-2V
OFFSET
VOLTAGE
4266 F12
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相關代理商/技術參數
參數描述
LTC4266IGW#PBF 功能描述:IC CTRLR IEEE 802.3AT 36-SSOP RoHS:是 類別:集成電路 (IC) >> 接口 - 控制器 系列:- 標準包裝:2,450 系列:- 控制器類型:SPI 總線至 I²C 總線橋接 接口:I²C，串行，SPI 電源電壓:2.4 V ~ 3.6 V 電流 - 電源:11mA 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:24-VFQFN 裸露焊盤 供應商設備封裝:24-HVQFN（4x4） 包裝:托盤 配用:568-3511-ND - DEMO BOARD SPI TO I2C 其它名稱:935286452157SC18IS600IBSSC18IS600IBS-ND
LTC4266IGW#TRPBF 制造商:Linear Technology 功能描述:Power Over Ethernet Controller 36-Pin SSOP W T/R 制造商:Linear Technology 功能描述:MS-Hot Swap/POE, PoE+ 25.5W Quad PSE Controller
LTC4266IUHF#PBF 制造商:Linear Technology 功能描述:POE Controller 25.5W 38-Pin QFN EP 制造商:Linear Technology 功能描述:IC POE 802.3AT QUAD PSE 38-QFN 制造商:Linear Technology 功能描述:POE CNTRL QUAD 25.5W 1MHZ 制造商:Linear Technology 功能描述:IC, POE CONTROLLER, 3.3V, QFN-38; Input Voltage:3.3V; Supply Current:-2.4mA; UVLO:25V; Digital IC Case Style:QFN; No. of Pins:38; Frequency:1MHz; Operating Temperature Min:-40C; Operating Temperature Max:85C; MSL:MSL 1 - Unlimited ;RoHS Compliant: Yes
LTC4266IUHF#TRPBF 制造商:Linear Technology 功能描述:POE Controller 25.5W 38-Pin QFN EP
LTC4267 制造商:LINER 制造商全稱:Linear Technology 功能描述:Quad IEEE 802.3at Power over Ethernet Controller
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