The Si3400 and Si3401 are Silicon Laboratories fully integrated 802.3-compliant PD interface and switching regulator, which converts the high voltage supplied over the 10/100/1000BASE-T Ethernet connection into a regulated, low-voltage output supply
The Si3400 and Si3401 are fully‑integrated Power‑over‑Ethernet (PoE) PD controller ICs that provide switching regulator and hotswap functions in a compact 5 × 5 mm QFN package. They support both isolated (flyback) and non‑isolated (buck) topologies and comply with IEEE 802.3 standards for PoE.
The document includes electrical specifications, pin descriptions, package information, typical application schematics, and ordering details, along with a change log and contact information for Silicon Laboratories.
| VPORT Minimum Voltage | 2.8 V |
|---|---|
| Switcher Frequency | 350 kHz |
| Thermal Shutdown Junction Temperature | 160 °C |
| Package Type | 5 × 5 mm QFN, 20‑pin |
The regulator switches at a typical frequency of 350 kHz.
Both devices are offered in a low‑profile 5 × 5 mm QFN package with 20 pins.