Overview: Si3404 Data Sheet Fully-Integrated IEEE 802.3 Type 1-Compliant POE PD Interface and High-Efficiency Switching Regulator with Compact Footprint
The Si3404 integrates the power management and control functions required in a Power-over-Ethernet (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 minimizes the solution footprint and external BOM cost and enables the use of low-cost external components while maintaining high performance. The Si3404 integrates a transient surge suppressor. The switching power FET and associated functions are also integrated. The integrated, current mode controlled switching regulator supports isolated or non-isolated flyback and buck converter topologies. The switching frequency for the regulator is tunable with a simple external resistor value to help avoid unwanted harmonics for better emissions control.
This device fully supports the IEEE 802.3at specification for Type 1, single-event classification. Standard external resistors provide the proper IEEE 802.3 signatures for the detection function and programming of the classification mode, and internal startup circuits ensure well-controlled soft-start initial operation of both the hotswap switch and the voltage regulator.
The Si3404 is available in a low-profile, 20-pin, 4 x 4 mm QFN package.
