MAX5941A

Features:

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
Programmable Undervoltage Lockout

PWM Controller
Wide Input Range: 18V to 67V
Current-Mode Control
Leading-Edge Blanking
Internally Trimmed 275kHz ±10% Oscillator Soft-Start

Application

IP Phones
Wireless Access Nodes
Internet Appliances
Computer Telephony
Security Cameras
Power Devices in Power-Over-Ethernet/
Power-Over-MDI


Pinout




Specifications

GND........................................................................-0.3V to +80V
OUT, PGOOD ...........................................  -0.3V to (GND + 0.3V)
RCL, GATE .............................................................-0.3V to +12V
UVLO........................................................................-0.3V to +8V
PGOOD to OUT.........................................  -0.3V to (GND + 0.3V)
V+ to V-...................................................................-0.3V to +80V
VDD to V-.................................................................-0.3V to +40V
VCC to V-..............................................................-0.3V to +12.5V
OPTO, NDRV, SS_SHDN, CS to V-.............   -0.3V to (VCC + 0.3V)
Maximum Input/Output Current (Continuous)
OUT to VEE ................................................................... 500mA
GND, RCL to VEE ............................................................  70mA
UVLO, PGOOD, PGOOD to VEE .....................................   20mA
GATE to VEE....................................................................80mA
VDD, VCC.........................................................................20mA
NDRV Continuous ...........................................................25mA
NDRV (Pulsed for less than 1µs) .......................................±1A
Continuous Power Dissipation (TA = +70°C)
16-Pin SO (derate 9.1mW/°C above +70°C)................727mW
Operating Temperature Range
MAX5941_CSE ..................................................0°C to +70°C
MAX5941_ESE ...............................................-40°C to +85°C
Storage Temperature Range .......................-65°C to +150°C
Junction Temperature.................................................+150°C
Lead Temperature (soldering, 10s)  ..........................+300°C


Description

The MAX5941A/MAX5941B integrate a complete power IC for powered devices (PD) in a power-over-ethernet (PoE) system. The MAX5941A/MAX5941B provide a PD interface and a compact DC-DC PWM controller suitable for flyback and forward converters in either isolated or nonisolated designs. The MAX5941A/MAX5941B 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 under- voltage lockout (UVLO) with wide hysteresis and power-good status outputs.

The MAX5941A/MAX5941B also integrate all the building blocks necessary for implementing DC-DC fixed-frequency isolated power supplies. These devices are 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 MAX5941A allows an 85% operating duty cycle and can be used to implement flyback converters. The MAX5941B limits the operating duty cycle to less than 50% and can be used in single-ended forward converters. The MAX5941A/MAX5941B are designed to work with or without an external diode bridge in front of the PD. The MAX5941A/MAX5941B are available in 16-pin SO
packages.