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參數(shù)資料
| 型號(hào)： | TPS2371PWG4 |
| 廠商： | Texas Instruments |
| 文件頁數(shù)： | 19/19頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC PWR INTRFCE SW FOR POE 8TSSOP |
| 標(biāo)準(zhǔn)包裝： | 150 |
| 應(yīng)用： | 用于以太網(wǎng)供電（PoE）設(shè)備的電源接口開關(guān) |
| 接口： | IEEE 802.3af |
| 封裝/外殼： | 8-TSSOP（0.173"，4.40mm 寬） |
| 供應(yīng)商設(shè)備封裝： | 8-TSSOP |
| 包裝： | 管件 |
| 安裝類型： | 表面貼裝 |
TPS2371
SLUS566A JULY 2003 REVISED NOVEMBER 2003
9
www.ti.com
APPLICATION INFORMATION
Classification of the PD is optionally performed by the PSE only after a valid PD has been detected. To determine
PD classification, the PSE increases the voltage across the power lines to between 15.5 V and 20.5 V. The
amount of current drawn by the PD determines the classification (see Table 2).
When the input voltage to the TPS2371 is between 14.0 V and 20.5 V, the TPS2371 uses an internal regulator
to generate a fixed voltage on the CLASS pin. A resistor connected between the CLASS pin and VEE draws
a fixed amount of current and thereby defines the classification level of the PD.
POWER SOURCING EQUIPMENT POWER TO THE POWERED DEVICE
Upon completion of the detection and optional classification phases, the PSE ramps its output voltage above
36 V . Once the UVLO threshold has been reached, the internal FET is turned on. At this point, the PD begins
to operate normally and it continues to operate normally as long as the input voltage remains above 30 V. For
most PDs, this input voltage is down-converted using an on board dc-to-dc converter to generate the required
voltages.
The TPS2371 is designed to apply the PSE output voltage of 36 V to 57 V across the input of the on board
dc-to-dc converter. This is accomplished on the TPS2371 by turning on an internal pass FET located across
the power return.
Programming the Inrush Current
During the initial turn-on of the pass FET, an inrush current is created from the charging of the capacitance at
the input of the dc-to-dc converter. According to the IEEE 802.3af specification, if the input capacitance is less
than 180-
F, the PSE limits the inrush current. If the input capacitance is greater than 180-F, the IEEE 802.3af
specification requires the PD to limit the inrush current to less than 400 mA.
In order to satisfy the IEEE 802.3af requirements, the TPS2371 has been designed for a typical current limit
of 450 mA. This current limit setting satisfies the normal operation requirements as well as the inrush
requirements for a capacitive load of 180-
F or less. If a larger load capacitor is desired, the TPS2371 has been
designed with a programmable inrush current limit feature. This feature allows the designer the option of using
a capacitor larger than 180-
F. Note that the inrush current feature may also be used to lower voltage drops
in the cabling between the PSE and the PD during startup.
The programmable inrush current limit has a range of 50 mA to 449 mA. The limit is set by connecting an external
resistor from ILIM (pin 1) to VEE (pin 4) of the TPS2371. Equation (3) shows the calculation for the
programmable inrush current limit.
I
INRUSH + 450 mA *
25 k
W
R
LIM
(1A)
where RLIM is a value between 63.5 k and 25 M.
(3)
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| TPS2371PWR | 功能描述:熱插拔功率分布 Legacy/IEEE802.3af Comp Pwr InterfSw RoHS:否 制造商:Texas Instruments 產(chǎn)品:Controllers & Switches 電流限制: 電源電壓-最大:7 V 電源電壓-最小:- 0.3 V 工作溫度范圍: 功率耗散: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
| TPS2371PWRG4 | 功能描述:熱插拔功率分布 Legacy/IEEE802.3af Comp Pwr InterfSw RoHS:否 制造商:Texas Instruments 產(chǎn)品:Controllers & Switches 電流限制: 電源電壓-最大:7 V 電源電壓-最小:- 0.3 V 工作溫度范圍: 功率耗散: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
| TPS2372-4RGWT | 功能描述:TPS2372 制造商:texas instruments 系列:* 包裝:剪切帶（CT） 零件狀態(tài):在售 封裝/外殼:20-VQFN 裸露焊盤 供應(yīng)商器件封裝:20-VQFN（5x5） 標(biāo)準(zhǔn)包裝:1 |
| TPS2373-4RGWT | 功能描述:IC POE CNTRL 20VQFN 制造商:texas instruments 系列:- 包裝:剪切帶（CT） 零件狀態(tài):在售 類型:控制器（PD） 通道數(shù):1 功率 - 最大值:71W 內(nèi)部開關(guān):是 輔助作用:是 標(biāo)準(zhǔn):802.3at（PoE+），802.3bt 電壓 - 電源:0 V ~ 57 V 電流 - 電源:20mA 工作溫度:-40°C ~ 125°C 封裝/外殼:20-VQFN 裸露焊盤 供應(yīng)商器件封裝:20-VQFN（5x5） 標(biāo)準(zhǔn)包裝:1 |
| TPS23750EVM-107 | 功能描述:電源管理IC開發(fā)工具 TPS23750 Eval Mod Buck RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
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