The PM8801 integrates a standards-compatible Power over Ethernet (PoE) interface with a current-mode PWM controller to simplify the design of the power portion of all powered devices. PoE/PoE+ interfaces integrate all the functions required by IEEE 802.3at, including detection, classification, undervoltage locking (UVLO), and inrush current limiting. PM8801 specifically performs IEEE802.3at Layer1 hardware classification, giving the rest of the system an indication of a successful detection by type 2 PSE.
Simplified application schematic diagram of a powered device using PM8801 preactive clamp configuration
The PM8801 is designed to use power from Ethernet cable connections or external power sources such as wall adapters, ensuring the prevalence of auxiliary power relative to PoE ports. The DC/DC portion of the PM8801 features programmable oscillator frequencies, adjustable slope compensation, dual complementary low-side drivers, programmable delay time, and internal temperature sensors.
Internal block diagram
The PM8801 is targeted for efficient conversion under all load conditions, supporting flyback, forward, forward active clamping, and synchronous rectification.
Dc module block diagram
