| Provides PoE converter circuit for class-8 rated PD
| Suitable for IP cameras, access control systems, shutter controllers
| Implementation of PWM controller for 48V isolated flyback

STMicroelectronics today introduced a new PD chipset that implements the latest IEEE 802.3bt PoE specification.
The PM8804 and PM8805 provide PoE converter circuits for PDs up to Class-8, defining a usable power specification of 71 W. The chipsets save space, improve reliability, and shorten time to market for next-generation connectivity equipment, including 5G ‘small cells’ and WLAN access points, switches, and routers.

It can also be applied to smart building and smart office applications such as IP cameras, access control systems, display panels, lighting, curtains, shutter controllers, video call systems, IP phones, and tablet consoles.

The PM8804 implements a PWM controller for a 48 V isolated flyback or forward converter, including dual low-side gate drivers for high-efficiency forward active-clamp topologies.

The operating frequency is selectable up to 1 MHz, allowing the use of decoupling components and small external filters for high power density. The PM8804 also features a high-voltage startup regulator with 20mA output capability, saving onboard space and bill of materials.

The companion chip, PM8805, includes two active bridges and a charge pump to drive the high-side MOSFETs, a hot-swap FET, and an IEEE 802.3bt-compliant interface. Integrating the active bridges saves space by consuming eight discrete MOSFETs and their driving circuitry.

The PM8805 generates a Power-Good signal to activate other circuits such as the PM8804 and the LED driver, and supports Maintain Power Signature (MPS) current control maintenance to allow the product to enter power-saving standby mode without interruption.

Both devices are now in production. The PM8804 is available in a 3 x 3, 0.5-mm pitch VFQFPN-16 package and is priced at $0.60 in 1,000-unit quantities. The PM8805 is available in a thermally enhanced 8 x 8-mm VFQFPN-43 package with exposed pad and is priced at $4.50.