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參數(shù)資料
| 型號(hào)： | LTC4268IDKD-1#PBF |
| 廠商： | Linear Technology |
| 文件頁(yè)數(shù)： | 16/46頁(yè) |
| 文件大?。?/td> | 419K |
| 描述： | IC PD HIGH POWER W/CNTRL 32-DFN |
| 產(chǎn)品培訓(xùn)模塊： | Power over Ethernet |
| 標(biāo)準(zhǔn)包裝： | 52 |
| 類型： | 以太網(wǎng)供電開關(guān)（PoE） |
| 應(yīng)用： | 遠(yuǎn)程外設(shè)（工業(yè)控制，相機(jī)，數(shù)據(jù)訪問(wèn)） |
| 內(nèi)部開關(guān)： | 是 |
| 工作溫度： | -40°C ~ 85°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 32-WFDFN 裸露焊盤 |
| 供應(yīng)商設(shè)備封裝： | 32-DFN（7x4）裸露焊盤 |
| 包裝： | 管件 |
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LTC4268-1
16
42681fc
applicaTions inForMaTion
classification for use in closed systems and is not defined
or supported by the IEEE 802.3af. With the extended clas-
sification range available in the LTC4268-1, it is possible
for system designers to define multiple classes using load
currents between 40mA and 75mA.
During classification, the PSE presents a fixed voltage
between 15.5V and 20.5V to the PD (Figure 5). With the
input voltage in this range, the LTC4268-1 asserts a load
current from the V
PORTP
pin through the R
CLASS
resistor.
The magnitude of the load current is set with the selection
of the R
CLASS
resistor. The resistor value associated with
each class is shown in Table 2.
A substantial amount of power is dissipated in the
LTC4268-1 during classification. The IEEE 802.3af specifi-
cation limits the classification time to 75ms in order avoid
excessive heating. The LTC4268-1 is designed to handle
the power dissipation during the probe period. If the PSE
probing exceeds 75ms, the LTC4268-1 may overheat. In
this situation, the thermal protection circuit will engage
and disable the classification current source, protecting
the LTC4268-1 from damage. When the die cools, clas-
sification is automatically resumed.
Classification presents a challenging stability problem
for the
PSE due to the wide range of loads possible. The
LTC4268-1 has been designed to avoid PSE interoperability
problems by maintaining a positive I-V slope throughout
the signature and classification ranges up to UVLO turn
on as shown in Figure 6. The positive I-V slope avoids
areas of negative resistance and helps prevent the PSE
from power cycling or getting stuck during signature
or classification probing. In the event a PSE overshoots
beyond the classification voltage range, the available load
current aids in returning the PD back into the classification
voltage range. (The PD input may otherwise be trapped
by a reverse-biased diode bridge and the voltage held by
the 0.1礔 capacitor.) By gently ramping the classification
current on and maintaining a positive I-V slope until UVLO
turn-on, the LTC4268-1 provides a well behaved load,
assuring interoperability with any PSE.
V
PORTP
R
CLASS
V
PORTN
LTC4268-1
CONSTANT
LOAD
CURRENT
INTERNAL
TO LTC4268-1
42681 F05
R
CLASS
CURRENT PATH
V
PD
PSE
PSE CURRENT MONITOR
PSE
PROBING
VOLTAGE
SOURCE
15.5V TO 20.5V
V
PORT
(V)
0
40
42681 F06
10
20
30
Figure 5. PSE Probing PD During Classification
Figure 6. LTC4268-1 Positive I-V Slope
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC4268IDKD-1-TR | 制造商:LINER 制造商全稱:Linear Technology 功能描述:High Power PD with Synchronous NoOpto Flyback Controller |
| LTC4268IDKD-1-TRPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:High Power PD with Synchronous NoOpto Flyback Controller |
| LTC4269-1 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:IEEE 802.3at PD with Synchronous No-Opto Flyback Controller |
| LTC4269-2 | 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-1#PBF | 功能描述:IC PD/OPTO FLYBACK CTRLR 32-DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 標(biāo)準(zhǔn)包裝:50 系列:- 類型:熱交換控制器 應(yīng)用:-48V 遠(yuǎn)程電力系統(tǒng)，AdvancedTCA ? 系統(tǒng)，高可用性 內(nèi)部開關(guān):無(wú) 電流限制:可調(diào) 電源電壓:11.5 V ~ 14.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬） 供應(yīng)商設(shè)備封裝:10-MSOP 包裝:管件 |
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