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参数资料
| 型号： | LTC4274AIUHF-2#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源管理 |
| 英文描述： | POWER SUPPLY MANAGEMENT CKT, PQCC38 |
| 封装： | 7 X 5 MM, LEAD FREE, PLASTIC, MO-220WHKD, QFN-38 |
| 文件页数： | 6/28页 |
| 文件大小： | 313K |
| 代理商： | LTC4274AIUHF-2#TRPBF |
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LTC4274A/LTC4274C
14
4274acf
Overview
Power over Ethernet, or PoE, is a standard protocol for
sending DC power over copper Ethernet data wiring.
The IEEE group that administers the 802.3 Ethernet data
standards added PoE powering capability in 2003. This
original PoE spec, known as 802.3af, allowed for 48V DC
power at up to 13W. This initial spec was widely popular,
but 13W was not adequate for some requirements. In
2009, the IEEE released a new standard, known as 802.3at
or PoE+, increasing the voltage and current requirements
to provide 25W of power.
The IEEE standard also defines PoE terminology. A device
that provides power to the network is known as a PSE, or
powersourcingequipment,whileadevicethatdrawspower
from the network is known as a PD, or powered device.
PSEs come in two types: Endpoints (typically network
switches or routers), which provide data and power; and
Midspans, which provide power but pass through data.
MidspansaretypicallyusedtoaddPoEcapabilitytoexisting
non-PoE networks. PDs are typically IP phones, wireless
access points, security cameras, and similar devices.
PoE++ Evolution
Even during the process of creating the IEEE PoE+ 25.5W
specification, it became clear that there was a significant
and increasing need for more than 25.5W of delivered
power. The LTC4274A family responds to this market by
allowing a reliable means of providing up to 90W of deliv-
ered power to a LTPoE++ PD. The LTPoE++ specification
providesreliabledetectionandclassificationextensionsto
the existing IEEE PoE technique that are backward com-
patible and interoperable with existing Type 1 and Type 2
PDs. Unlike other proprietary PoE++ solutions, Linear’s
LTPoE++ solution provides mutual identification between
the PSE and PD. This ensures that the LTPoE++ PD knows
it may use the requested power at start-up because it has
detected a LTPoE++ PSE. LTPoE++ PSEs can differentiate
between a LTPoE++ PD and all other types of IEEE compli-
ant PDs allowing LTPoE++ PSEs to remain compliant and
interoperable with existing equipment.
pin Functions
GATE: Gate Drive. GATE should be connected to the gate
of the external MOSFET for the port. When the MOSFET
is turned on, the gate voltage is driven to 13V (typ) above
VEE. During a current limit condition, the voltage at GATE
will be reduced to maintain constant current through the
external MOSFET. If the fault timer expires, GATE is pulled
down, turning the MOSFET off and recording a tCUT or
tSTART event.
OUT: Output Voltage Monitor. OUT should be connected
to the output port. A current limit foldback circuit limits
the power dissipation in the external MOSFET by reduc-
ing the current limit threshold when the drain-to-source
voltage exceeds 10V. The Power Good bit is set when the
voltage from OUT to VEE drops below 2.4V (typ). A 500k
resistor is connected internally from OUT to AGND when
the port is idle.
VEE: Main Supply Input. Connect to a –45V to –57V
supply, relative to AGND.
AUTO: AUTO Pin Mode Input. AUTO pin mode allows the
LTC4274A/LTC4274C to detect and power up a PD even
if there is no host controller present on the I2C bus. The
voltage of the AUTO pin determines the state of the internal
registers when the LTC4274A/LTC4274C is reset or comes
out of VDD UVLO (see the LTC4274A/LTC4274C Software
Programmingdocumentation).Thestatesoftheseregister
bits can subsequently be changed via the I2C interface.
The real-time state of the AUTO pin is read at bit 0 in the
Pin Status register (11h). Internally pulled down to DGND.
Must be tied locally to either VDD or DGND.
MSD: Maskable Shutdown Input. Active low. When pulled
low, all ports that have their corresponding mask bit set
in the Misc Config register (17h) will be reset, equivalent
to pulling the SHDN pin low. Internal filtering of the MSD
pin prevents glitches less than 1s wide from resetting
ports. Internally pulled up to VDD.
operAtion
相关PDF资料 |
PDF描述 |
|---|---|
| LTC4274AIUHF-2#PBF | POWER SUPPLY MANAGEMENT CKT, PQCC38 |
| LTC4274AIUHF-1#TRPBF | POWER SUPPLY MANAGEMENT CKT, PQCC38 |
| LTC4280IUFD | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PQCC24 |
| LTC4312IDE#TRPBF | 2-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO14 |
| LTC4312CDE#PBF | 2-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO14 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC4274AIUHF-3#PBF | 功能描述:IC CONTROLLER POE 38-QFN 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) |
| LTC4274AIUHF-3#TRPBF | 功能描述:IC CONTROLLER POE 38-QFN 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) |
| LTC4274AIUHF-4#PBF | 功能描述:IC CONTROLLER POE 38-QFN 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) |
| LTC4274AIUHF-4#TRPBF | 功能描述:IC CONTROLLER POE 38-QFN 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) |
| LTC4274C | 制造商:LINER 制造商全称:Linear Technology 功能描述:12-Port PoE/PoE+/LTPoE++ PSE Controller |
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