PWM Controller 16-Pin SOIC N

The MAX5942A/MAX5942B integrate a complete power IC for powered devices (PD) in a power-over-ethernet (PoE) system. The MAX5942A/MAX5942B provide a PD interface and a compact DC-DC PWM controller suitable for flyback and forward converters in either isolated or nonisolated designs. The MAX5942A/MAX5942B PD interface complies 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 power-good status outputs. The MAX5942A/MAX5942B also integrate all the building blocks necessary for implementing DC-DC fixed-frequency isolated power supplies. This device is a current-mode controller with an integrated high startup circuit suitable for isolated telecom/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 275kHz ±10%, thus reducing magnetics and filter components. The MAX5942A 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.

• Powered Device Interface
  • Fully Integrated IEEE 802.3af-Compliant 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/Active-Low PGOOD Outputs Enable PWM Controller

PWM Controller

• Wide Input Range: 18V to 67V
• Isolated (Without Optocoupler) or Nonisolated Power Supply
• Current-Mode Control
• Leading-Edge Blanking
• Internally Trimmed 275kHz ±10% Oscillator
• Soft-Start