This document focuses on a reference design for a simple, low cost 5 V 2 A flyback converter based on the PM8800A device. The PM8800A is a highly integrated device embedding a “Powered Device” (PD) interface together with a PWM controller.
It can be successfully used in all low power, low cost PoE applications.

PD interface
Works with power supplied from Ethernet LAN cables or from local auxiliary sources
Line input voltage range: 40 Vdc to 60 Vdc output voltage: 5 Vdc ± 5%
Output current: 2 A
Peak-to-peak output ripple: 30 mV
Efficiency DC-DC full-load: > 86%
Efficiency overall peak: > 84%
Transient response ΔVoutpk-pkto 50% load step: < 300m Vpp
ΔV in load line case: < 0.5%