The PM8800 from STMicroelectronics is an IEEE 802.3af-Compliant Power-Over-Ethernet (PoE) IC that has been designed to simplify the design of the power supply sections of all powered devices. This PoE IC requires an input voltage of 48 V. It consists of an AUX manager, high-voltage startup regulator, DC/DC controller, power-good control logic, gate controller, thermal protection, interface manager, and current and voltage sense circuitries. This PoE IC specifically targets powered devices with an extended power requirement to the limit imposed by the 802.3af standard and embeds a hot-swap MOSFET capable of sustaining twice the current of the 802.3af standard with a programmable DC current limit. It integrates a switching regulator that has been designed to work with power supplied either from an Ethernet cable connection or an external power source, such as an AC adapter.
This PoE IC’s DC-DC section includes a programmable oscillator frequency, soft-start, and slope compensation, and embeds a voltage output error amplifier, allowing usability in both isolated and non-isolated configurations. It incorporates all the functions required by IEEE 802.3af, including detection, classification, under-voltage lockout (UVLO), and in-rush current limitations to prevent false triggers or short-circuit-related damages. This PoE IC is available in a surface-mount package that measures 5.10 x 6.60 x 1.20 mm and is ideal for VoIP phones, WLAN access points, security cameras, PoE-powered device appliances, and high-power (>12.95 W) powered device applications.