Stmicroelectronics S.r.l.

Riccardo Russo

Aldo Torazzina

PDs that can be supplied through the LAN line are discriminated from PDs that cannot be so supplied as a function of the resistance of the supply line and of the voltage drop caused by nonlinear elements in series therewith. The values of these two parameters are estimated by applying two distinct voltages to the supply terminals of the LAN line and sensing the relative steady-state currents absorbed by the power supply line, and by processing voltage and current values for estimating the resistance of the line and the voltage drop caused by nonlinear elements connected in series therewith.

Method of discrimination of a device as powerable through a LAN line and device for estimating electric parameters of a LAN line

A circuit is for monitoring the powering of a remote device through a LAN without generating an extra biasing voltage higher than the DC power supply voltage. DC voltage used for supplying the remote device is applied to the LAN line while an AC voltage is applied to the line for monitoring whether the remote device is connected to the LAN line. The DC voltage is applied to a first or 'high' terminal and the AC voltage is applied to the other or 'low' terminal of the LAN line through a decoupling capacitor. This arrangement allows the supplying of the remote device with a large DC voltage compatible with a fully integrated AC signal generator, disconnection detector, and PSE controller, and enhances the reliability of the recognition of whether the powered device is connected to, or disconnected from, the LAN line.

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Milan, Italy

Riccardo Russo