System Board 6288 MAXREFDES98 : NON-ISOLATED 5V/2.5A POE POWERED DEVICE POWER SUPPLY To meet the increasing demands for non-isolated Power over Ethernet (PoE) power solutions, Maxim has developed innovative, non-isolated PoE powered device (PD) power solutions. Each design was tested for load and line regulation, as well as efficiency and transient performance. As with all Maxim reference designs, the BOM, schematics, layout files, and Gerber files are all available and may be downloaded from the Design Resources tab. In addition, boards are available for purchase. These boards feature a module architecture, with through-hole pins for immediate board placement and accelerated prototyping. MAXREFDES98 combines the PD controller and the step down converter on a 14.0mm (0.55in) x 55.9mm (2.2in) board. The module accepts input voltages ranging from 36V to 57V, and provides an output voltage of 5V with current capacity of 2.5A. For initial evaluation, Maxim also provides an evaluation board, MAXREFDES98EV . This board features RJ45 connectors for quick testing with sourced power. Features 36V ~ 57V input voltage Compact and flexible Minimal external components Robust operation in adverse environments 12.5W output capacity 3% output accuracy Applications Lighting IP cameras Sensors Non-isolated Ethernet equipment Introduction Power over Ethernet (PoE) provides power to Ethernet connected devices, through Ethernet lines, eliminating the need for connecting AC mains to the target devices. In addition to reducing cabling, PoE provides multiple advantages for many applications such as LED lighting, cameras, sensors, and additional equipment. These advantages include network management of devices, power measurement, and elimination of AC/DC circuitry. Many PoE applications are isolated, to protect both people and systems from voltage and current transients. However, many applications do not require isolation, such as LED lighting and other equipment that is generally out of range for human touch. In these cases, eliminating the isolation circuitry further reduces cost and power dissipation at the PoE point of load. MAXREFDES98 is a unique PoE module reference design, providing 5V at 2.5A (12.5W) from a 36V to 57V input. This design can be used for evaluation, design, prototyping, and production. MAXREFDES98 includes two function blocks: the PD controller block and the step down DC-DC power supply block. The PD controller uses the MAX5969A. The MAX5969A is an IEEE 802.3af compliant, powered device interface controller with an integrated power MOSFET. The DC-DC power supply uses the MAX17503. The MAX17503 is a 4.5V~60V input, 2.5A output, high-efficiency synchronous step down converter with internal compensation. The entire design delivers a peak efficiency of 86% with an input of 48V. The MAXREFDES98 features 12 through-hole pins spaced at a 2.54mm pitch standard. This modular architecture allows MAXREFDES98 to be soldered into a PCB or inserted into the MAXREFDES98EV for evaluation.