The Pasadena (MAXREFDES31#) reference design features the MAX5969B and MAX5974A (see Figure 1). The MAX5969B controller is fully compliant with the IEEE® 802.3af/at standard in a power-over-Ethernet (PoE) system. The device can also be powered from a wall adapter (WAD). The WAD operates with higher priority than PoE, which is controlled by the MAX5969B. The MAX5974A controls 40V to 57V input-voltage, current-mode PWM converters and provides frequency foldback. Using these devices, this reference design is IEEE 802.3af/at compliant. It is also a high-performance, compact, and cost-effective solution for a PD supporting power up to Class 4 power level.