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): 15/30頁
文件大?。?/td> 823K
代理商: TPS23753PW
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0.01mF
SLVS853C – JUNE 2008 – REVISED JANUARY 2010
www.ti.com
The least popular technique is PoE priority. It is implemented by placing a diode between the PD supply voltage,
VDD, and the dc/dc controller bias voltage, VDD1. The diode prevents reverse biasing of the PoE input diode
bridges when option 2 adapter ORing is used. The PSE may then detect, classify, and provide power to the PD
while a live adapter is connected. As long as the PoE voltage is greater than the adapter voltage, the PSE will
power the load. The APD function is not used in this technique.
The IEEE standards require that the Ethernet cable be isolated from ground and all other system potentials. The
adapter must meet a minimum 1500 Vac dielectric withstand test between the output and all other connections
for options 1 and 2. The adapter only needs this isolation for option 3 if it is not provided by the converter.
Adapter ORing diodes are shown for all the options to protect against a reverse voltage adapter, a short on the
adapter input pins, and damage to a low-voltage adapter. ORing is sometimes accomplished with a MOSFET in
option 3.
Protection
A TVS across the rectified PoE voltage per Figure 1 must be used. An SMAJ58A, or a part with equal to or better
performance, is recommended for general indoor applications. If an adapter is connected from VDD1 to RTN, as
in ORing option 2 above, voltage transients caused by the input cable inductance ringing with the internal PD
capacitance can occur. Adequate capacitive filtering or a TVS must limit this voltage to be within the absolute
maximum ratings. Configurations that use DVDD as in Figure 25 may require additional protection against ESD
transients that would turn DVDD off and force all the voltage to appear across the internal hotswap MOSFET.
CVDD and DRTN per Figure 25 provide this additional protection.
Figure 25.
Outdoor applications require more extensive protection to lightning standards.
Frequency Dithering for Conducted Emissions Control
The international standard CISPR 22 (and adopted versions) is often used as a requirement for conducted
emissions. Ethernet cables are covered as a telecommunication port under section 5.2 for conducted emissions.
Meeting EMI requirements is often a challenge, with the lower limits of Class B being especially hard. Circuit
board layout, filtering, and snubbing various nodes in the power circuit are the first layer of control techniques. A
more detailed discussion of EMI control is presented in Practical Guidelines to Designing an EMI Compliant PoE
Powered Device With Isolated Flyback, TI literature number SLUA469. Additionally, IEEE802.3at section 33.4
has requirements for noise injected onto the Ethernet cable based on compatibility with data transmission.
22
Copyright 2008–2010, Texas Instruments Incorporated
Product Folder Link(s): TPS23753
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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