STHS4257A1M6F STMicroelectronics, STHS4257A1M6F Datasheet - Page 5

• Manufacturer Part Number: STHS4257A1M6F
• Description: IC CTLR PD IEEE 802.3AF 8SOIC
• Manufacturer: STMicroelectronics

Specifications of STHS4257A1M6F

• Controller Type: Power over Ethernet Controller (POE)
• Interface: IEEE 802.3af
• Voltage - Supply: 5V
• Current - Supply: 50µA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6323-2

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:
●
●
These devices have an integrated high voltage power MOSFET (low-side switch) with low
R
and V
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
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
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
ON
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.
and the capability to accept transients as high as 100V. Since the pins (such as GND
IN
) which interface to the RJ-45 socket can routinely see high peak voltages in excess
Figure 1 on page 6
and
IN
pins (see
Table 2 on page
Table 1 on page
Figure 4 on page
6). The STHS4257 family also
1.
8).
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