STMicroelectronics introduces advanced chipsets for PoE converter circuits

     STMicroelectronics' new chipset enables users to take advantage of the latest Power over Ethernet (PoE) specification, IEEE 802.3bt, to rapidly develop reliable, space-saving electrical devices (PD). Both products are already in mass production. The PM8804 comes in a 3mm x 3mm, 0.5mm pitch VFQFPN-16 package. The PM8805 comes in a bare pad 8mm x 8mm heat enhanced VFQFPN-43 package.

     The PM8804 and PM8805 can be used as PoE converter circuits for electrical devices, supporting Class 8 PoE devices with power levels up to 71W. The new chipset saves board space, enhances product reliability, and reduces time to market for next-generation communication connected devices, including 5G "small cells," WLAN access points, switches, and routers. Targeted applications for STMicroelectronic's new PoE chipset also include smart building and smart office equipment, such as IP cameras, access control systems, display panels, lamps, electric curtain or blind controllers, video calling systems, IP phones and desktop consoles.

     The PM8804 enables a fully functional PWM controller for 48V isolated flyback or forward converters, as well as dual low-side gate drivers for efficient active clamp forward converter topologies. Operating frequencies are optional, up to 1MHz, allowing the use of small external filters and decoupling components in high power density applications. The PM8804 also features a high voltage start regulator with a 20mA output, helping to save board space and bill of materials.

     The PM8805 supporting chip contains two active Bridges, a charge pump for driving high-side MOSFETs, a hot-swapable FETs, and an IEEE 802.3bt standard interface. The integrated active bridge saves space occupied by eight discrete MOSFETs and their driver circuits. The PM8805 generates a power ready signal that enables the PM8804 and other circuits (e.g., LED drivers) and supports maintenance of power signature (MPS) current control, allowing electrical devices to enter a power-saving standby state without disconnecting.