Power Electronics

PSE Controller’s Capabilities Exceed PoE Requirements

Maxim Integrated Products has released the MAX5945, a quad IEEE802.3af-compliant power-sourcing-equipment (PSE) controller for Power over Ethernet (PoE). In full compliance with the IEEE802.3af standard, the MAX5945 provides discovery, classification, current limit, and both dc and ac load disconnect detection to a powered device (PD). This controller is fully software configurable, and a watchdog feature allows system hardware to gracefully take over control if the system software fails. The MAX5945 also supports both midspan (power injector) and endpoint switch/router (LAN) PSE applications. In addition, the device operates over an extended temperature range of -40°C to +85°C.

To ensure interoperability, both the PSE and PD devices must comply with the IEEE802.3af standard. As a high-performance PoE controller, the MAX5945 has all the capabilities a designer needs to meet IEEE802.3af requirements. The MAX5945's gate charging current, current-limit threshold, startup timeout, overcurrent timeout and auto restart duty-cycle features are all programmable. A class-overcurrent detection function enables the system to determine if a powered device (PD) is drawing more current than allowed for its class. Other standard features include input undervoltage/overvoltage lockout, output voltage slew-rate limit, overtemperature protection, and “power-good” and “fault” status outputs. The device can operate autonomously or be controlled by software through an I²C-compatible interface. The MAX5945 is packaged in a 36-pin SSOP package. With samples available now, pricing starts at $6.81 for 1000-unit quantities.

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