2 Detailed description
The PM8803 evaluation board, STEVAL-TSP009V2, has been designed to cover a broad
range of Power over Ethernet (PoE) applications. The PM8803 is a highly integrated device
embedding an IEEE802.3af/at-compliant powered device (PD) interface together with a
PWM controller and support for auxiliary sources. Although the PM8803 can be configured
to work in several isolated topologies (self-driven or transformer gate-driven), the focus
here is on a high-efficiency isolated flyback converter topology with synchronous
rectification, 3.3 V output voltage with 6 A output current capability.
Auxiliary sources can be connected to the board on 2 different input connectors. One input
(AUX II) allows prevalence of the auxiliary sources with respect to the PoE, while the other
input (AUX I) allows the use of a wall adapter with voltage lower than the internal PoE
UVLO threshold, while still benefitting from the inherent inrush and DC current limit. The
possible configurations supported by the PM8803 evaluation board as options on the same
PCB are:
Input diode bridges; 4 possible options, including active bridges
Optional 4-pair detection circuit, to detect a high power PSE source
Optional booster circuit, to increase the max input current over 800 mA
Diode or synchronous rectification; 4 package options for diode and 3 package options
for MOSFET
Primary side snubber; 3 options including active clamp
Power transformer; 3 size options for transformer gate-driven solutions and 2 size
options for self-driven applications
