Monolithic Quad PSE Controller Enables IEEE 802.3at Applications

Maxim has introduced the MAX5965, a monolithic quad PSE controller for IEEE 802.3at/PoE+ and IEEE 802.3af-compliant PoE applications. This device allows multiport PoE systems to deliver up to 45W over standard Cat5 Ethernet cable to power devices such as IP phones, wireless LAN access nodes, and IP cameras. The controller is well suited for both endpoint (LAN switches/routers) and midspan (power injectors) PSE applications. The MAX5965 is pin and function compatible with the MAX5945/LTC4258/LTC4259A 802.3af quad PSE controllers, plus has additional features, thus allowing customers to upgrade their 802.3af PSE systems for higher power with minimal hardware changes.

Operating from 32V to 60V, the MAX5965 is rated for an absolute maximum of 80V. It provides 802.3af PD discovery and classification, and offers Class 5 and Class 6 classification for detection of high-power PDs. It also supports both DC and AC load-disconnect detection methods. The MAX5965's internal 9-bit ADC and I2C interface allows advanced power management and power budgeting in multiport PSE systems. To ensure interoperability, the MAX5965 is capable of detecting legacy (non-IEEE 802.3af compliant) PDs that use high capacitance as the discovery signature.

Numerous programming and configuration options give the MAX5965 unmatched design flexibility. This device can be controlled with a system microcontroller (such as the MAXQ2000), or it can be configured to operate autonomously. The MAX5965 can also be configured to operate in manual or semiautomatic modes, providing design flexibility as well as field debug and diagnostic capabilities. The gate-charging current, current-limit threshold, startup timeout, overcurrent timeout, and autorestart duty cycle are all programmable. Other features include: UVLO (undervoltage-lockout) detection and protection, a load-stability safety check during UVLO detection, overtemperature protection, output-voltage slew-rate limiting during startup, and power-good/fault-status indicators.

Maxim offers reference designs for both endpoint PSE or midspan PSE applications. The midspan reference designs can be configured to support up to 192 ports and include a MAXQ2000 microcontroller and supporting software. Contact the factory for more information.


The MAX5965 is offered in a 36-pin SSOP package and is rated to operate in the upper commercial temperature range (0 degrees Celsius to +85 degrees Celsius). Prices start at $4.54 (1000-up FOB USA); production samples are available.