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參數(shù)資料
| 型號： | LTC4269CDKD-2 |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING CONTROLLER, 560 kHz SWITCHING FREQ-MAX, PDSO32 |
| 封裝： | 7 X 4 MM, PLASTIC, M0-229, DFN-32 |
| 文件頁數(shù)： | 13/34頁 |
| 文件大?。?/td> | 383K |
| 代理商： | LTC4269CDKD-2 |
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LTC4269-2
0
42692fb
These options come with various trade-offs and design
considerations. Contact Linear Technology applications
support for detailed information on implementing custom
auxiliary power sources.
IEEE 802.3AT SYSTEM POWER-UP REQUIREMENT
Under the IEEE 802.3at standard, a PD must operate
under 12.95W in accordance with IEEE 802.3at standard
until it recognizes a Type 2 PSE. Initializing PD operation
in 12.95W mode eliminates interoperability issue in case
a Type 2 PD connects to a Type 1 PSE. Once the PD rec-
ognizes a Type 2 PSE, the IEEE 802.3at standard requires
the PD to wait 80ms in 12.95W operation before 25.5W
operation can commence.
MAINTAIN POWER SIGNATURE
In an IEEE 802.3af/at system, the PSE uses the maintain
power signature (MPS) to determine if a PD continues to
requirepower.TheMPSrequiresthePDtoperiodicallydraw
at least 10mA and also have an AC impedance less than
26.25k in parallel with 0.05F. If one of these conditions
is not met, the PSE may disconnect power to the PD.
Isolation
The802.3standardrequiresEthernetportstobeelectrically
isolatedfromallotherconductorsthatareuseraccessible.
This includes the metal chassis, other connectors, and any
auxiliary power connection. For PDs, there are two com-
mon methods to meet the isolation requirement. If there
are any user-accessible connections to the PD, then an
isolatedDC/DCconverterisnecessarytomeettheisolation
requirements. If user connections can be avoided, then it
is possible to meet the safety requirement by completely
enclosing the PD in an insulated housing.
Switcher Controller Operation
The LTC4269-2 has a current mode synchronous PWM
controller optimized for control of a forward converter
topology. The LTC4269-2 is ideal for power systems
where very high efficiency and reliability, low complexity
and cost are required in a small space. Key features of the
LTC4269-2includeanadaptivemaximumdutycycleclamp.
Figure 8. T2P Interface Examples
applicaTions inForMaTion
42692 F08
OPTION 1: SERIES CONFIGURATION FOR ACTIVE LOW/LOW IMPEDANCE OUTPUT
–54V
TO
PSE
RP
TO PD’s
MICROPROCESSOR
TO PD’s
MICROPROCESSOR
VPORTP
VPORTN
T2P
V+
OPTION 2: SHUNT CONFIGURATION FOR ACTIVE HIGH/OPEN COLLECTOR OUTPUT
–54V
TO
PSE
RP
VPORTP
LTC4269-2
VPORTN
VNEG
T2P
V+
DC/DC converter isolation barrier. The pull-up resistor RP
is sized according to the requirements of the opto-isola-
tor operating current, the pull-down capability of the T2P
pin, and the choice of V+. V+ for example can come from
the PoE supply rail (which the LTC4269-2 VPORTP is tied
to), or from the voltage source that supplies power to
the DC/DC converter. Option 1 has the advantage of not
drawing power unless T2P is declared active.
Shutdown Interface
To corrupt the signature resistance, the SHDN pin can be
driven high with respect to VPORTN. If unused, connect
SHDN directly to VPORTN.
Exposed Pad
TheLTC4269-2usesathermallyenhancedDFN12package
that includes an Exposed Pad. The Exposed Pad should
be electrically connected to the GND pin’s PCB copper
plane. This plane should be large enough to serve as the
heat sink for the LTC4269-2.
Auxiliary Power Source
In some applications, it is desirable to power the PD from
an auxiliary power source such as a wall adapter. Auxiliary
power can be injected into the PD at several locations with
priority chosen between PoE or auxiliary power sources.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC4269CDKD-2#PBF | 功能描述:IC PD/SYNC FORWARD CTRLR 32-DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:119 系列:- 類型:熱交換控制器 應(yīng)用:通用型，PCI Express? 內(nèi)部開關(guān):無 電流限制:- 電源電壓:3.3V，12V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:80-TQFP 供應(yīng)商設(shè)備封裝:80-TQFP（12x12） 包裝:托盤 產(chǎn)品目錄頁面:1423 (CN2011-ZH PDF) |
| LTC4269CDKD-2#TRPBF | 功能描述:IC PD/SYNC FORWARD CTRLR 32-DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 產(chǎn)品培訓(xùn)模塊:Obsolescence Mitigation Program 標準包裝:100 系列:- 類型:熱插拔開關(guān) 應(yīng)用:通用 內(nèi)部開關(guān):是 電流限制:可調(diào) 電源電壓:9 V ~ 13.2 V 工作溫度:-40°C ~ 150°C 安裝類型:表面貼裝 封裝/外殼:10-WFDFN 裸露焊盤 供應(yīng)商設(shè)備封裝:10-TDFN-EP（3x3） 包裝:管件 |
| LTC4269CDKD-2-PBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:IEEE 802.3at High Power PD and Synchronous Forward Controller with AUX Support |
| LTC4269CDKD-2-TR | 制造商:LINER 制造商全稱:Linear Technology 功能描述:IEEE 802.3at High Power PD and Synchronous Forward Controller with AUX Support |
| LTC4269CDKD-2-TRPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:IEEE 802.3at High Power PD and Synchronous Forward Controller with AUX Support |
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