The Power by Linear LTC4291/LTC4292 provides up to 71W of power via 4 independent PSE ports supporting 2 channels each, ensuring fully compliant support for the next generation of IEEE 802.3bt powered devices (PDs). The LTC4291 includes a digital interface to the PSE host, while the LTC4292 implements the high voltage Ethernet power interface. The two devices communicate 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 LTC4291/LTC4292 chipset operates with compliant 802.3bt PD controllers, the LT4294 or LT4295, forming complete end-to-end PoE++, PoE+ and PoE solutions. Up to 71.3W of power can be delivered to single-signature or dual-signature PDs with robust 80V pins. The LTC4291/LTC4292 is Analog Devices’ first 802.3bt PSE controller and provides an upgrade path from the LTC4266 4-port 802.3at PSE controller.
PD discovery is accomplished using a multipoint voltage and current detection mechanism, ensuring the best immunity from false PD detection and power management includes 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 while a 1MHz I2C interface allows a host controller to digitally configure the chipset or query port status. Power management demonstration libraries written in ANSI C 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.
Pricing for the 24pin LTC4291 starts at $2.00 and $6.00 for the 40pin LTC4292 and both are available now.