ST's advanced chipset provides users with new 100W Ethernet power standard

A new chipset from STMicroelectronics enables users to quickly develop reliable, space-saving Powered Devices (PDs) taking advantage of the latest Power-over-Ethernet (PoE) specification, IEEE 802.3bt.

PM8804 and PM8805 can be used in PoE converter circuits for power-consuming devices, supporting Class 8 PoE devices with a maximum power level of 71W. The new chipset saves circuit board space, enhances product reliability, and shortens time to market, and is suitable for next-generation communication connection devices, including 5G "small cells", WLAN access points, switches, and routers. STMicroelectronics' new PoE chipset also targets smart building and smart office equipment, such as IP cameras, access control systems, display panels, lamps, electric curtains or blinds controllers, video call systems, IP phones, and desktop consoles.

The PM8804 implements a fully functional PWM controller for 48V isolated flyback or forward converters, as well as dual low-side gate drivers for high-efficiency active clamp forward converter topologies. The selectable operating frequency up to 1MHz allows the use of small external filter and decoupling components in high power density applications. The PM8804 also features a high-voltage startup regulator with a 20mA output, helping to save board space and bill of materials.

The PM8805 companion chip includes two active bridges, a charge pump for driving high-side MOSFETs, a hot-swap FET, and an IEEE 802.3bt standard interface. The integrated active bridge saves the space occupied by eight discrete MOSFETs and their drive circuits. The PM8805 generates a power-ready signal to enable the PM8804 and other circuits (e.g., LED drivers) and supports maintain power signature (MPS) current control, allowing power-consuming devices to enter a power-saving standby state without disconnecting.

Both products are in production now. The PM8804 is available in a 3mm x 3mm, 0.5mm pitch VFQFPN-16 package. The PM8805 is available in a 8mm x 8mm thermally enhanced VFQFPN-43 package with an exposed pad.