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參數(shù)資料
| 型號(hào)： | TPS2370PW |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 電源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO8 |
| 封裝： | GREEN, PLASTIC, TSSOP-8 |
| 文件頁數(shù)： | 17/17頁 |
| 文件大小： | 426K |
| 代理商： | TPS2370PW |
TPS2370
SLUS537C AUGUST 2002 REVISED MARCH 2004
www.ti.com
9
APPLICATION INFORMATION
SURGE SUPPRESSION
As specified in the Absolute Maximum Ratings table, the absolute maximum input voltage of the TPS2370 is
68 V. The IEEE 802.3af Power-over-Ethernet Standard specifies the voltage range of PSE output as between
44 V and 57 V. This PSE output voltage range would be reduced by cable, connector, and other IR drops
between the PSE and the TPS2370 in the PD. However, the use of extended cable lengths and transformers in
some applications may induce transients in excess of 68 V during a hot plug event. To manage these transient
events and keep them from significantly exceeding the application’s maximum voltage, a transorb such as the
SMAJ54A should be placed between the positive input supply, VDD (pin 8), and the negative input supply, VEE
(pin 4). This, combined with a 0.1-
F bypass capacitor in parallel with the transorb, helps to protect the TPS2370
from damage caused by transients during hot plug events. The transorb or zener diode should be selected such
that it does not zener below the maximum required application voltage of 57 V, but before reaching the 68-V
absolute maximum rating. For layout purposes, the 0.1-
F capacitor should be placed as close as possible to the
device; the transorb or zener diode should be placed as close to the supply connector as possible. Based on the
nature of the PD application, these measures should be considered an implementation requirement.
USE OF BARREL RECTIFIERS
Many applications use barrel rectifiers after the RJ-45 connector in order to be polarity insensitive. Barrel
rectifiers in front of the TPS2370 cause the voltages at the device to be lower than the voltages at the RJ-45.
The TPS2370 allows for this and is IEEE802.3af compliant during the detection and classification phases. For
the detection phase, the device begins detection for voltages as low as 1.3 V across the supply pins. For the
optional classification phase, the device is guaranteed to start classification below 14 V across the supply pins.
Once classification has been engaged, it becomes latched-in and further voltage drops due to cable resistance
and class current does not cause it to switch out of classification. Thus, the TPS2370 allows for at least a 1.5-V
drop between the RJ-45 and the TPS2370 due to barrel rectifiers during both detection and classification phases.
However, in cases where the PSE is operating at the minimum class voltage (15.5 V) and there is a 20-
, 100-m
cable between the PSE and the PD, class 3 devices may not classify correctly when using barrel rectifiers. Class
3 device designs should include Schottky diodes to handle all corner cases, or switch to class 0 devices when
using barrel rectifiers.
THERMAL SHUTDOWN
In the event of a short circuit or overload condition, the TPS2370 begins to heat up until thermal shutdown is
reached. Once thermal shutdown is reached, the internal FET is switched off, removing the load from the supply.
After the device has cooled sufficiently, it retries by restarting the internal FET. If the overload or short is not
removed, the device cycles thermal shutdown seven times before latching the internal FET off. Once the internal
FET is latched off, power needs to be cycled to reset the latch.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TPS2370PWG4 | 功能描述:熱插拔功率分布 IEEE 802.3af Pwr Ifc Switch For PoE PD’s 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 |
| TPS2370PWR | 功能描述:熱插拔功率分布 IEEE 802.3af Pwr Ifc Switch For PoE PD’s 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 |
| TPS2370PWRG4 | 功能描述:熱插拔功率分布 IEEE 802.3af Pwr Ifc Switch For PoE PD’s 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 |
| TPS2371D | 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 |
| TPS2371DG4 | 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 |
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