ADI has released the Power by Linear LTC4291 / LTC4292 isolated four-port PSE controller chipset, which was created for use in IEEE 802.3bt (PoE ++) PoE systems. These devices provide four independent PSE ports, each of which consists of two channels to ensure full compatibility with next-generation IEEE 802.3bt PD. The LTC4291 includes a digital interface to the PSE host, while the LTC4292 implements a high-voltage Ethernet power interface. The two ICs use an inexpensive Ethernet transformer for interworking. Transformer-isolated communication protocols can replace up to six expensive optocouplers and complex isolated 3.3V power supplies used in traditional designs, which can save significant BOM costs, and make the design more robust and easy to manufacture.
The chipset works seamlessly with compatible 802.3bt PD controllers and these devices, resulting in complete end-to-end PoE ++, PoE + and PoE solutions. Single- or dual-signature PDs can transmit power up to 71.3W. Users will welcome the ruggedness of the 80V pin. The use of multi-point voltage and current detection mechanisms enables PD discovery to ensure optimal resistance against false PD detection. Advanced power management includes Autoclass support, priority fast shutdown, 14-bit power and current readback per port, 8-bit programmable power limit and 7-bit programmable overload current limit. The system can be updated with field-upgraded firmware. The 1MHz I2C interface provides a host controller to digitally configure the chipset or query the port status. A power management "C" demo library is also provided to reduce NRE and shorten time to market. The LTC4291 / LTC4292 chipset is available in the industrial temperature range. The LTC4291 digital controller is available in a RoHS-compliant 24-pin 4mm x 4mm QFN package, while the LTC4292 analog controller is available in a 40-pin 6mm x 6mm QFN package.
