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參數(shù)資料
| 型號： | TPS23753PW |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 0.505 A SWITCHING CONTROLLER, 273 kHz SWITCHING FREQ-MAX, PDSO14 |
| 封裝： | GREEN, PLASTIC, TSSOP-14 |
| 文件頁數(shù)： | 14/30頁 |
| 文件大小： | 823K |
| 代理商： | TPS23753PW |
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Optional for PoE Priority
5/8/08
www.ti.com
SLVS853C – JUNE 2008 – REVISED JANUARY 2010
diode ORing external power into a PD. Only one option would be used in any particular design. Option 1 applies
power to the TPS23753 PoE input, option 2 applies power between the TPS23753 PoE section and the power
circuit, and option 3 applies power to the output side of the converter. Each of these options has advantages and
disadvantages. A detailed discussion of the TPS23753 and ORing solutions is covered in application note
Advanced Adapter ORing Solutions using the TPS23753, literature number SLVA306.
Figure 24. ORing Configurations
Preference of one power source presents a number of challenges. Combinations of adapter output voltage
(nominal and tolerance), power insertion point, and which source is preferred determine solution complexity.
Several factors which add to the complexity are the natural high-voltage selection of diode ORing (the simplest
method of combining sources), the current limit implicit in the PSE, and PD inrush and protection circuits
(necessary for operation and reliability). Creating simple and seamless solutions is difficult if not impossible for
many of the combinations. However the TPS23753 offers several built-in features that simplify some
combinations.
Several examples will demonstrate the limitations inherent in ORing solutions. Diode ORing a 48 V adapter with
PoE (option 1) presents the problem that either source might be higher. A blocking switch would be required to
assure which source was active. A second example is combining a 12 V adapter with PoE using option 2. The
converter will draw approximately four times the current at 12 V from the adapter than it does from PoE at 48 V.
Transition from adapter power to PoE may demand more current than can be supplied by the PSE. The
converter must be turned off while CIN capacitance charges, with a subsequent converter restart at the higher
voltage and lower input current. A third example is use of a 12 V adapter with ORing option 1. The PD hotswap
would have to handle four times the current, and have 1/16 the resistance (be 16 times larger) to dissipate equal
power. A fourth example is that MPS is lost when running from the adapter, causing the PSE to remove power
from the PD. If ac power is then lost, the PD will stop operating until the PSE detects and powers the PD.
The most popular preferential ORing scheme is option 2 with adapter priority. The hotswap MOSFET is disabled
when the adapter is used to pull APD high, blocking the PoE source from powering the output. This solution
works well with a wide range of adapter voltages, is simple, and requires few external parts. When the ac power
fails, or the adapter is removed, the hotswap switch is enabled. In the simplest implementation, the PD will
momentarily loose power until the PSE completes its startup cycle.
The DEN pin can be used to disable the PoE input when ORing with option 3. This is an adapter priority
implementation. Pulling DEN low, while creating an invalid detection signature, disables the hotswap MOSFET
and prevents the PD from redetecting. This would typically be accomplished with an optocoupler that is driven
from the secondary side of the converter.
Copyright 2008–2010, Texas Instruments Incorporated
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Product Folder Link(s): TPS23753
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TPS23753PW | 制造商:Texas Instruments 功能描述:Controller IC |
| TPS23753PWG4 | 功能描述:熱插拔功率分布 PoE Interface & Iso Cnvrtr & Cntrlr 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 |
| TPS23753PWR | 功能描述:熱插拔功率分布 Interface and Iso Cnvrtr and Cntrlr 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 |
| TPS23753PWRG4 | 功能描述:熱插拔功率分布 PoE Interface & Iso Cnvrtr & Cntrlr 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 |
| TPS23754EVM-383 | 功能描述:電源管理IC開發(fā)工具 TPS23754 Eval Mod 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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