MAX5942A Datasheet | Maxim Integrated

Description The MAX5942A/MAX5942B integrate a plete power IC for powered devices (PD) in a power-over-ethernet (Po E) system. The MAX5942A/MAX5942B provide a PD interface and a pact DC-DC PWM controller suitable for flyback and forward converters in either isolated or nonisolated designs. The MAX5942A/MAX5942B PD interface plies with the IEEE 802.3af standard, providing the PD with a detection signature, a classification signature, and an integrated isolation switch with programmable inrush current control. These devices also feature power-mode undervoltage lockout (UVLO) with wide hysteresis and powergood status outputs. The MAX5942A/MAX5942B also integrate all the building blocks necessary for implementing DC-DC fixedfrequency isolated power supplies. This device is a current-mode controller with an integrated high startup circuit suitable for isolated tele/industrial voltage range power supplies. A high-voltage startup circuit allows the PWM controller to draw power directly from the 18V to 67V input supply during startup. The switching frequency is internally trimmed to 275k Hz ±10%, thus reducing magnetics and filter ponents. The MAX59412A allows an 85% operating duty cycle and can be used to implement flyback converters. The MAX5942B limits the operating duty cycle to less than 50% and can be used in single-ended forward converters. The MAX5942A/MAX5942B are designed to work with or without an external diode bridge in front of the PD. The MAX5942A/MAX5942B are available in 16-pin SO packages. Features o Powered Device Interface Fully Integrated IEEE 802.3af-pliant PD Interface PD Detection and Programmable Classification Signatures Less than 10µA Leakage Current Offset During Detection Integrated MOSFET for Isolation and Inrush Current Limiting Gate Output Allows External Control of the Internal Isolation FET Programmable Inrush Current Control/ULVO PGOOD/PGOOD Outputs Enable PWM Controller o PWM Controller Wide Input Range: 18V to 67V Isolated (Without...