New POE IC packs in features while upping power efficiency

Akros Silicon cannily plays the efficiency card with its new AS1854 POE PD (powered device) IC – both energy and space efficiency. Akros claims that the integration of parts into the 1854 PD controller platform accounts for greater than 75% savings in board space, and 25% in BOM savings.The chip enables higher power efficiency with its GreenEdge synchronous rectification, which the company claims can yield an greater than 8% improvement in efficiency in the 6-8W “sweet spot” range that’s typical for VOIP phones, currently the most common application for POE. GreenEdge digital isolation technology also provides 2kV on-chip isolation, eliminating the need for opto-isolators that add cost, space and reduce system reliability. Isolation is necessary in PDs between the power management circuitry for the system devices, such as VOIP phone electronics and display, and between the primary side electronics and sensor control circuits.

POE systems require a “master” PSE (power sourcing equipment) that provides power to networked equipment via the Ethernet cable. For an IEEE 802.3at (draft) version, the PSE must allocate up to 25.5W per PD, and 4.5W of cable loss. The AS1854 enables network power management in that the PSE can query the PD and find out its actual power usage as well as its cable losses rather than relying on a worst-case power budget. In a network with multiple PDs, the power budget can quickly add up. By allocating power accurately rather relying on a worst-case power budget, total network power can be managed efficiently.

Budgetary pricing  for the AS1854 is $4.69 USD