TPS2383

` Compliant to Power Over Ethernet IEEE 802.3af Standard
` Two-Point 25-k Resistor Discovery
` Capacitive Detection for Non-Compliant Legacy Loads
` Power Classification
` Controlled di/dt Ramp Power-Up and Power-Down for EMI Reduction
` Current Management for Charging Powered Device Bulk Capacitance
` Electronic Circuit Breaker
` Fault detection
` Input Undervoltage Lockout (UVLO)
` Load Overcurrent and Undercurrent Detection
` 12-Bit Port Current and Voltage Acquisition
` Standard Slave I²C Serial Interface
` 5-Bit Serial Address Selectability
` Discovery and/or Classification Bypass Modes Selectable Via Register
` Opto-Coupler Compatible SDA and SCL Lines for System Ground Isolation
` Dual Color LED Driver for Port Status
` Hardware FAULT Interrupt
` Single +48-V Supply Capable

· PoE Switches
· Mid-Span Injectors

(1) Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. All voltages are with respect to GND. Currents are positive into and negative out of, the specified terminal.

The TPS2383 family of products are power sourcing equipment power managers (PSEPM) that are compliant to the power-over-ethernet (PoE) IEEE 802.3af Standard. A PSEPM port can discover, classify and deliver power to a powered device (PD) capable of accepting PoE twisted pair cable. The TPS2383 is fully programmable by the user. This allows for the detection and powering of both fully compliant 802.3 devices as well as custom detection of legacy devices.

The TPS2383 PSEPM can individually manage power for up to eight ethernet ports. All operations of the TPS2383 are controlled through register read and write operations over a standard (slave) I²C serial interface.

The TPS2383 has dual SDA lines to allow easy application of opto-coupler circuitry to maintain ethernet port isolation when a ground based controller is used. Each TPS2383 has five selection pins making it possible to address up to 32 devices on the I²C bus and allows individual control and monitoring of up to 256 ethernet ports from a single master I²C controller. Per-port write registers initiate and manipulate the flow of the discovery, classification, and power-up states while the read registers contain status information of the enable process, faults, classification value, and real time port operating current and voltage. Per-port status LED drivers are provided which can be manually controlled through the serial I/O.

The TPS2383 is available in a full function 64-pin LQFP.

External N-channel MOSFETs switch port power. High-voltage (HV) gate drive ensures that these FETs are fully enhanced, resulting in lower power dissipation and enabling the use of lower costs FETs. The TPS2383 generates its HV gate supply from the 48-V port power, simplifying system power supply design. An external 3.3-V digital supply is also used. This supply can be active when 48-V power is not present which allows the user to access the part through the serial I/O in this case. A 5-V analog supply is used to power port LEDs and internal analog functions. Due to the very low quiescent current, both the 3.3-V and 5-V supply can be generated from the +48-V power bus with minimal external components. An internal power-on-reset (POR) circuit with an ORed external input pin resets all registers positions to a known safe state upon power up.