A Design of Powered Device Interface Chip under PoE System

This paper proposes a design of powered device interface chip compatible with communication protocol IEEE 802.at standard, for Ethernet control of power supply. This design has all the features IEEE 802.at standard requires, including the detection, classification, under-voltage lockout and inrush current control, support of not less than 25.5W of power. The circuit of the chip is designed with Hangzhou Silan BCD process technique. Specific features of the design are 140mA inrush-current-limiting, complementary-output-enable-signal, under-voltage, overvoltage, over temperature protection, an optional external power adapter input, IEEE 802.3at type2 display signals by new electrical equipment, as well as two-event classification logic implementation.