PoE Controllers Pack IEEE802.3af Interface January 2004 Issue Published Date: January 13, 2004
The MAX5941 and MAX5942 debut as the industry's first power-over-Ethernet (PoE) dc/dc controllers that integrate an IEEE802.3af-compliant interface controller. The controllers are capable of powering devices such as IP phones, wireless LAN access points, and IP cameras. Both devices are rated for up to 67V operation and deliver over 15W of output power. And each provides a valid 25 k? signature discovery, classification signature, and programmable inrush current. During detection, the ICs draw less than 10 µA of offset current, allowing for accurate detection of the 25 k? signature. Other shared features include a current-mode PWM controller with an integrated startup circuit, current-mode control, leading-edge blanking, soft-start, over-current shutdown and under-voltage lockout, and thermal shutdown. MAX5941 is specified for isolated forward and flyback converters and MAX5942 is recommended for non-isolated designs. Prices start at $1.47 for MAX5941 and $1.55 for MAX5942 each/1,000. For more information, contact MAXIM INTEGRATED PRODUCTS, Sunnyvale, CA. (800) 998-8800.
