Analog Devices has released the Power by Linear LTC4291/LTC4292 isolated four-port PSE controller chipset created for use in IEEE 802.3bt (PoE++) PoE systems. The devices provide four independent PSE ports composed of two channels each, assuring fully compliant support for the next generation of IEEE 802.3bt PDs. The LTC4291 includes a digital interface to the PSE host, while the LTC4292 implements the high voltage Ethernet power interface. The two ICs intercommunicate using an inexpensive Ethernet transformer. The transformer-isolated communication protocol replaces up to six expensive opto-couplers and a complex isolated 3.3V supply used in traditional designs, resulting in significant BOM cost savings and a more robust and easy to manufacture design.
The chipset operates seamlessly with compliant 802.3bt PD controllers, the devices, forming complete end-to-end PoE++, PoE+ and PoE solutions. Up to 71.3W of power can be conveyed to single-signature or dual-signature PDs. Users will welcome the robustness of the 80V pins. PD discovery is achieved using a multipoint voltage and current detection mechanism, securing the best immunity from false PD detection. Advanced power management comprises Autoclass support, prioritized fast shutdown, 14-bit per-port power and current readback, 8-bit programmable power limits and 7-bit programmable overload current limits. Systems can be updated with field-upgradable firmware. A 1MHz I2C interface provides a host controller to digitally configure the chipset or query port status. Power management ‘C’ demonstration libraries are also available to reduce NRE and improve time to market. The LTC4291/LTC4292 chipset is offered in the industrial temperature range. The LTC4291 digital controller is in a RoHS-compliant 24-pin 4mm x 4mm QFN package, while the LTC4292 analog controller is in a 40-pin 6mm x 6mm QFN package.