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参数资料
| 型号： | LTC4269CDKD-2#TR |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING CONTROLLER, 560 kHz SWITCHING FREQ-MAX, PDSO32 |
| 封装： | 7 X 4 MM, PLASTIC, M0-229, DFN-32 |
| 文件页数： | 13/34页 |
| 文件大小： | 383K |
| 代理商： | LTC4269CDKD-2#TR |
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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.
相关PDF资料 |
PDF描述 |
|---|---|
| LTC4269IDKD-2 | SWITCHING CONTROLLER, 560 kHz SWITCHING FREQ-MAX, PDSO32 |
| LTC4269CDKD-2 | SWITCHING CONTROLLER, 560 kHz SWITCHING FREQ-MAX, PDSO32 |
| LTC4269IDKD-2#TR | SWITCHING CONTROLLER, 560 kHz SWITCHING FREQ-MAX, PDSO32 |
| LTC4412IS6#TR | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO6 |
| LTC4412IS6#TRM | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO6 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC4269CDKD-2-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:IEEE 802.3at High Power PD and Synchronous Forward Controller with AUX Support |
| LTC4269IDKD-1#PBF | 功能描述:IC PD/OPTO FLYBACK CTRLR 32-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:119 系列:- 类型:热交换控制器 应用:通用型，PCI Express? 内部开关:无 电流限制:- 电源电压:3.3V，12V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:80-TQFP 供应商设备封装:80-TQFP（12x12） 包装:托盘 产品目录页面:1423 (CN2011-ZH PDF) |
| LTC4269IDKD-1#TRPBF | 功能描述:IC PD/OPTO FLYBACK CTRLR 32-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:100 系列:- 类型:热插拔开关 应用:通用 内部开关:是 电流限制:可调 电源电压:9 V ~ 13.2 V 工作温度:-40°C ~ 150°C 安装类型:表面贴装 封装/外壳:10-WFDFN 裸露焊盘 供应商设备封装:10-TDFN-EP（3x3） 包装:管件 |
| LTC4269IDKD-1-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:IEEE 802.3at PD with Synchronous No-Opto Flyback Controller |
| LTC4269IDKD-1-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:IEEE 802.3at PD with Synchronous No-Opto Flyback Controller |
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