Download Reference Design DocumentThe Reference Design Document describes the hardware pictured below. It provides a detailed systematic technical guide to designing a PoE powered device and 12V/600mA No-Opto flyback DC-DC converter using the MAX17690 and MAX5969B. The hardware was built according to the linked Schematic, Bill of Materials and PCB Artwork. It was tested by Maxim’s expert applications engineering team in a state-of-the-art design lab and the Test Results are fully documented. Functionality of the design over all electrical operating conditions was verified with the MAXREFDES1177 Simulation Circuit using Maxim’s OASIS Circuit Simulation Tool. Downloadable ECAD/EDA files are available in 7 different formats including OrCAD, Altium, Mentor DX Designer, Eagle and more.
| Input Type | VIN (MIN) (V) |
VIN (MAX) (V) |
IOUT (A) |
Single/Multiple Output |
VOUT (V) |
POUT (W) |
Isolated/Non-Isolated | Topology |
|---|---|---|---|---|---|---|---|---|
| DC | 30 | 60 | 0.6 | Single | 12 | 7.2 | Isolated | Flyback |
Power over Ethernet (PoE) is a technology that allows network cables to deliver power to a powered device (PD) through power-sourcing equipment (PSE) or midspan, and has many advantages over traditional methods of delivering power. PoE allows power and data to be combined, removing the need for altering the AC mains infrastructure and can be installed by non-electricians. PoE is an intelligent system designed with protection at the forefront, preventing overload, underpowering, and installation errors, while allowing simple scalability and reliability.
The MAX17690 implements an innovative algorithm to accurately determine the output voltage by sensing the reflected voltage across the primary winding during the flyback time interval. By sampling and regulating this reflected voltage when the secondary current is close to zero, the effects of secondary-side DC losses in the transformer winding, the PCB tracks, and the rectifying diode on output voltage regulation can be minimized. The MAX17690 also compensates for the negative temperature coefficient of the rectifying diode.
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