The MAX5995A/MAX5995B/MAX5995C provide a complete interface for a powered device (PD) to comply with the IEEE® 802.3af/at/bt standard in a Power-Over-Ethernet (PoE) system. The devices provide the PD with a detection signature, classification signature, and an integrated isolation power switch with startup inrush current control. During the startup period, the devices limit the current to 135mA (typ) before switching to the higher current limit (1800mA to 2400mA, typ) when the isolation power MOSFET is fully enhanced. The devices feature Multi-Event classification, Intelligent MPS (MAX5995B/MAX5995C), Autoclass (MAX5995C), an input UVLO with wide hysteresis and long deglitch time to compensate for twistedpair cable resistive drop and to assure glitch-free transition during power-on/-off conditions. The devices can withstand a maximum voltage of 100V at the input.
The devices support a Multi-Event classification method, as specified in the IEEE 802.3bt standard, and provide a signal to indicate from Type 1 to Type 4 Power Sourcing Equipment (PSE). The devices can detect the presence of a wall adapter power source connection and allow a smooth switch-over from the PoE power source to the wall power adapter.
The devices also provide a power-good (PG) signal, two-step current limit and foldback control, overtemperature protection. A sleep mode feature in the MAX5995A/MAX5995B minimizes low power consumption while generating the Maintain Power Signature (MPS) to maintain PSE connection. An Ultra-Low-Power sleep mode feature in the MAX5995A/MAX5995B further reduces power consumption while still generating MPS current. The MAX5995B/MAX5995C provides Intelligent Maintain Power Signature (IMPS) feature to automatically enable MPS current by detecting the port current.The devices feature a LED driver that is activated during sleep mode, Ultra-Low-Power sleep mode(MAX5995A/MAX5995B), and Intelligent MPS mode(MAX5995B/MAX5995C). Multi-Event indication feature provides patterned signals to indicate power level allocated from PSE to PD in 5 different scenarios. The MAX5995C provides Autoclass feature to enable advanced applications that allow the PSE to effectively optimize power allocation to PD.
The MAX5995A/MAX5995B/MAX5995C are available in a 16-pin, 5mm x 5mm, TQFN power package. These devices are rated over the -40°C to 125°C (MAX5995AATE/BATE/CATE) and -40°C to 85°C (MAX5995AETE/BETE/CETE) temperature ranges.
Applications
- Building Automation
- IEEE 802.3bt Powered Devices
- Lighting
- Small Cell, Pico Cell
- VOIP Phones, IP Security Cameras
- Wireless Access Point
