Powered Device Design Made Easy: Using the MPLAB® Analog Designer

The main end applications powered by Power over Ethernet (PoE) technology are wireless access points, IP phones and security cameras. A key benefit of PoE technology is that only the Ethernet cable needs to be routed to the end device, allowing virtually unlimited placement within a building. The incoming voltage into the PoE-powered device (PD) is between 44V and 57V. An isolated power supply is needed to step down the voltage to levels such as 3.3V, 5V, etc. that are required to power the internal circuits of the end application.

How to design this power supply? Microchip provides application notes and evaluation boards with various power supply topologies to guide you through product development. Application notes AN3468 and AN3471 cover the general theory, design details and PCB layout guidelines for developing a powered device using the Microchip PD front-end ICs (the PD701xx and PD702xx series devices). 

Also available are evaluation boards with many combinations of output voltages and currents to cover most application needs. But where to start? That is where the MPLAB® Analog Designer helps with your PoE design.

The MPLAB Analog Designer is easy to use with minimal inputs. Simply enter the output voltage and current to start the design. The results will show existing reference designs that either match or closely match your inputs. A link to an evaluation board will appear if one exists that matches your inputs. The power supply topology and expect efficiency is also displayed. You can view or modify the presented design and select to export the design files to use with the MPLAB® Mindi™ Analog Simulator for deeper analysis. 

All component values are standard values and components can be individually changed. The tool includes a performance option to optimize the design for either high performance (i.e., highest efficiency) or lowest cost. When finished, you will have a schematic and component list for your power supply design.

Using our application notes and the MPLAB Analog Designer online development tool is a great way to jump start your PD power supply design. Once complete, the next step is to submit your design for a review using our PoE Check Review service. This review process will provide guidance on the schematic, component selection and PCB layout of your design. 

Visit PoE for more details about Microchip Power over Ethernet products and solutions.