NCP1031POEEVB: 6.5 W PoE DC-DC Converter Evaluation Board

This article describes a method for solving the Power over Ethernet (POE) problem using ON Semiconductor’s NCP1031 series of monolithic high voltage switching regulators with internal MOSFETs. The NCP1031POE evaluation board is an inexpensive, high efficiency, 6.5 W output power at 5.0 V DC and associated input circuitry for responding to POE detection and classification protocols. The input is nominally 48 Vdc and the output is 5 Vdc with a maximum current of 1.3 A. There is additional input circuitry for responding to Ethernet protocols defined as “signature” and “classification” detection. The signature simply indicates that power is indeed present, and classification allows the upstream power sourcing equipment (PSE) to determine the rated power level of the power source or powered device (PD). Both detection modes are performed at low input voltages where the main converter is not operating. The converter only starts when Vin is above 35 Vdc.


A solution to one aspect of Power Over Ethernet (POE) is presented here utilizing the ON Semiconductor NCP1031 series of monolithic, high voltage switching regulators with internal MOSFET. The NCP1031POE evaluation board is an inexpensive, high efficiency, 6.5 W, 5.0 V DC output power supply along with the associated input circuitry for responding to POE detection and classification protocol. The input is 48 Vdc nominal and the output is 5 Vdc at 1.3 A maximum. There is additional input circuitry that responds to Ethernet protocol defined as 'Signature' and 'Classification' detection. Signature just indicates that the power supply does exist and classification allows the upstream Power Sourcing Equipment (PSE) to determine the rated power level of the supply or Powered Device (PD). Both of these detection modes are performed at low input voltages in which the main converter does not operate. The converter will only come on with Vin above 35 Vdc.