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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)： | 7/30頁 |
| 文件大?。?/td> | 823K |
| 代理商： | TPS23753PW |
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SLVS853C – JUNE 2008 – REVISED JANUARY 2010
The detection resistance seen by the PSE at the PI is the result of the input bridge resistance in series with the
parallel combination of RDEN and the TPS23753 bias loading. The input diode bridge’s incremental resistance
may be hundreds of Ohms at the very low currents drawn when 2.7 V is applied to the PI. The input bridge
resistance is partially cancelled by the TPS23753's effective resistance during detection.
Hardware Classification
Hardware classification allows a PSE to determine a PD’s power requirements before starting and helps with
power management once power is applied. The maximum power entries in Table 2 determine the class the PD
must advertise. A Type 1 PD may not advertise Class 4. The PSE may disconnect a PD if it draws more than its
stated Class power. The standard permits the PD to draw limited current peaks, however the average power
requirement always applies.
Voltage between 14.5 V and 20.5 V is applied to the PD for up to 75 ms during hardware Classification. A fixed
output voltage is sourced by the CLS pin, causing a fixed current to be drawn from VDD through RCLS. The total
current drawn from the PSE during classification is the sum of bias and RCLS currents. PD current is measured
and decoded by the PSE to determine which of the five available classes is advertised (see Table 2). The
TPS23753 disables classification above VCU_OFF to avoid excessive power dissipation. CLS voltage is turned off
during PD thermal limit or when APD or DEN are active. The CLS output is inherently current limited, but should
not be shorted to VSS for long periods of time.
Table 2. Class Resistor Selection
POWER AT PD PI
Class Current Requirement
CLASS
RESISTOR (
)
NOTES
MINIMUM
MAXIMUM
MAXIMUM (W)
MINIMUM (mA)
(W)
(mA)
0
0.44
12.95
0
4
1270
1
0.44
3.84
9
12
243
2
3.84
6.49
17
20
137
3
6.49
12.95
26
30
90.9
4
12.95
25.5
36
44
63.4
Only permitted for type 2 devices
Maintain Power Signature (MPS)
The MPS is an electrical signature presented by the PD to assure the PSE that it is still present after operating
voltage is applied. A valid MPS consists of a minimum dc current of 10 mA (at a duty cycle of at least 75 ms on
every 225 ms) and an ac impedance lower than 26.25 k
in parallel with 0.05 μF. The ac impedance is usually
accomplished by the minimum CIN requirement of 5 μF. When APD or DEN are used to force the hotswap switch
off, the dc MPS will not be met. A PSE that monitors the dc MPS will remove power from the PD when this
occurs. A PSE that monitors only the ac MPS may remove power from the PD.
TPS23753 Operation
Startup and Converter Operation
The internal PoE UVLO (Under Voltage Lock Out) circuit holds the hotswap switch off before the PSE provides
full voltage to the PD. This prevents the converter circuits from loading the PoE input during detection and
classification. The converter circuits will discharge CIN, CVC, and CVB while the PD is unpowered. Thus VRTN-VDD
will be a small voltage just after full voltage is applied to the PD, as seen in Figure 18.
The PSE drives the PI voltage to the operating range once it has decided to power up the PD. When VDD rises
above the UVLO turn-on threshold (VUVLO-R, ~35 V) with RTN high, the TPS23753 enables the hotswap
MOSFET with a ~140 mA (inrush) current limit. Refer to the waveforms of Figure 19 for an example. Converter
switching is disabled while CIN charges and VRTN falls from VDD to nearly VSS, however the converter startup
circuit is allowed to charge CVC. Once the inrush current falls about 10% below the inrush current limit, the PD
control switches to the operational level (~450 mA) and converter switching is permitted.
Copyright 2008–2010, Texas Instruments Incorporated
15
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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