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參數(shù)資料
| 型號(hào)： | STHS4257L |
| 廠商： | 意法半導(dǎo)體 |
| 英文描述： | IEEE 802.3af PoE Powered Device (PD) Interface Controller with Integrated Signature Resistor(集成識(shí)別電阻的IEEE802.3af PoE PD 接口控制器) |
| 中文描述： | IEEE 802.3af標(biāo)準(zhǔn)的PoE供電設(shè)備（PD）接口控制器，它集成簽名電阻（集成識(shí)別電阻的IEEE802.3af標(biāo)準(zhǔn)PoE電源接口控制器） |
| 文件頁(yè)數(shù)： | 5/18頁(yè) |
| 文件大?。?/td> | 173K |
| 代理商： | STHS4257L |
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STHS4257A, STHS4257A1, STHS4257L, STHS4257L1
Summary description
5/18
1
Summary description
The STHS4257 is an IEEE802.3af-compliant family of interface controllers for Power over
Ethernet (PoE) Powered Device (PD) applications. The devices consist of two main
sections:
The IEEE802.3af interface to the PoE powered RJ-45 wall socket, and
the Hot Swap Controller (HSC) functions required to protect the PD during insertion,
operation, and withdrawal from the RJ-45 socket.
●
●
These devices have an integrated high voltage power MOSFET (low-side switch) with low
R
ON
and the capability to accept transients as high as 100V. Since the pins (such as GND
and V
IN
) which interface to the RJ-45 socket can routinely see high peak voltages in excess
of 100V, it is strongly recommended that board designers protect the PD device with a
transient voltage suppressor, such as the SMAJ58A (available from STMicroelectronics),
connected between the GND and V
IN
pins (see
Figure 4 on page 8
).
The IEEE802.3af-compliant interface includes the basic PD detection and Classification
functions, whereas the ‘Hot Swap’ functions include other basic features, such as Inrush
Current Limiting, Undervoltage Lockout (UVLO), and Thermal Overload Protection. All of the
devices include an open drain Power Good (PWRGD) signal to indicate normal steady
operation (see
Figure 1 on page 6
and
Table 2 on page 6
). The STHS4257 family also
incorporates a 1.5V voltage offset (two series diodes) to accommodate the input diode
bridge used to make the PD polarity insensitive.
The STHS4257A1/L1 includes a dual level current limit circuit. This allows the
STHS4257A1/L1 to interface with legacy Power over Ethernet (LAN) systems while
maintaining compatibility with the current IEEE 802.3af specification.
Each of the two basic part types, the STHS4257A/L and the STHS4257A1/L1, is available
either with Latched Operation (L) Mode or with Automatic Retry (A) Mode after fault
conditions. For product options overview see
Table 1 on page 1
.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
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