Si3406x Family Data Sheet
Fully-Integrated IEEE 802.3-Compliant POE+ PD Interface and
High-Efficiency Switching Regulators with Transistor Bypass,
Sleep, Wake, and LED Drive
KEY FEATURES
• Type 1 (PoE) or Type 2 (PoE+) power
• Full IEEE 802.3at compliance
• Synchronous secondary FET driver
• Current mode dc-dc converter
• Tunable switching frequency
The Si3406x family integrates all power management and control functions required in
a Power-over-Ethernet Plus (PoE+) powered device (PD) application. These devices
convert the high voltage supplied over the 10/100/1000BASE-T Ethernet connection to
a regulated, low-voltage output supply. The optimized architecture of this device family
minimizes the solution footprint and external BOM cost and enables the use of low-cost
external components while maintaining high performance. The Si3406x family integra-
tes the required diode bridges and transient surge suppressor, thus enabling direct
connection of the IC to the Ethernet RJ-45 connector. The switching power FET and all
associated functions are also integrated. The integrated, current mode controlled
switching regulator supports isolated or non-isolated flyback and buck converter topolo-
gies. The switching frequency for the regulator is tunable with a simple external resistor
value to help avoid unwanted harmonics for better emissions control. A synchronous
driver is provided to optionally drive a secondary side FET to improve efficiency of pow-
er conversion. Connection to the PSE switch is maintained during sleep by an optional
automated maintain-power-signature (MPS) signal.
• Auxiliary transformer winding support
• Auxiliary adapter support
• Internal hotswap and switching FET bypass
support
• Automated maintain-power-signature (MPS)
support
• Sleep mode augmented with wake pin,
mode control, and LED driver
• 120 V Absolute Max voltage performance
• Extended –40 to +85 °C temperature
• Compact ROHS-compliant 5 mm x 5 mm
QFN Package
These devices fully support the IEEE 802.3at specification for the cases of single or
two event classification. Standard external resistors provide the proper IEEE 802.3 sig-
natures for the detection function and programming of the classification mode, and in-
ternal startup circuits ensure well-controlled soft-start initial operation of both the hots-
wap switch and the voltage regulator.
APPLICATIONS
• Voice over IP telephones
• Wireless access points
• Security and surveillance IP cameras
• Lighting luminaires
The Si34061 and Si34062 add main transformer bias winding support for ultra-high-effi-
ciency operation.
The Si34061 includes support for external augmentation or full bypass of the internal
hotswap and/or switching FET for best power handling and thermal management at the
high end of Class 4, plus offers a further boost in power conversion efficiency when
needed.
• Point-of-sale terminals
• Internet appliances
• Network devices
The Si34062 includes support for sleep modes with wake function, as well as LED drive
capability. These features can be utilized to minimize standby current, control sleep
and wake states, and provide application status information using a solid or blinking
LED.
The Si3406 is available in a low-profile, 20-pin, 5 x 5 mm QFN package, and the
Si34061 and Si34062 are available in low-profile, 24-pin, 5 x 5 mm QFN packages.
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This information applies to a product under development. Its characteristics and specifications are subject to change without notice.
Preliminary Rev. 0.5