Simplified Block Diagram
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- IEEE 802.3af-Compliant Power-Sourcing Equipment (PSE) Circuit
- Input Voltages
- -32V to -60V Providing 2A (-48V Power Circuit, 350mA/Port)
- +3.3V Providing 100mA (Digital Logic Power)
- VCC (+3.3V) Provides 100mA (Optical Interface)
- +9V Provides 250mA (SMBus LPT Interface Board)
- Ethernet Network Ports
- Four RJ-45 10/100 Base-TX Ethernet Network Input Ports
- Four RJ-45 10/100 Base-TX Ethernet Network Output Power-Over-Ethernet Ports
- Demonstrates Four Separate Independent Power Switch Controllers
- Provides PD Detection and Classification
- Configurable DC/AC Load Removal Detection and Disconnect Monitoring
- Configurable Current Sensing
- Convenient Voltage and Current Test Points
- Four Output-Port LED Status Indicators
- Optically Isolated 3-Wire I²C-Compliant PC Interface
- Reconfigurable for Stand-Alone Operation or with External Microcontroller
- Windows 95/98/2000-Compatible Software
- Fully Assembled and Tested
- Midspan Power Injector
- Power-Sourcing Equipment (PSE)
The MAX5945 EV kit requires a -32V to -60V power supply (-48V supply rail) capable of supplying 2A or more to the EV kit for powering the power device (PD) through the four 10/100 base-TX Ethernet network ports. The EV kit demonstrates PD discovery, classification, current-limit control and other functions of an IEEE 802.3af-compliant PSE. The user must also supply two separate 3.3V power supplies capable of supplying 100mA for the EV kit's digital logic and 3.3V (VCC) optically isolated 3-wire interface. The MAXSMBus interface board requires a dedicated 9V power supply capable of supplying 250mA. The +9V power supply is not required for nonisolated operation.
The MAX5945 controls the -48V DC power to each of the four Ethernet network ports by controlling each port's power MOSFET and sensing current through the respective port's current-sense resistor. The current is fed to a 10/100 base-TX Voice-over-IP (VoIP) magnetic module at each Ethernet network output port. The MAX5945 EV kit provides a separate independent power channel for each of the four Ethernet network output ports.
The EV kit demonstrates the full functionality of the MAX5945 for each power channel such as configurable operational modes, PD detection, PD classification, overcurrent protection, current foldback, under/overvoltage protection, and AC disconnect monitoring. All of these features are configurable on the EV kit and additional test points for voltage probing and current measurements have been provided.