4.4

Port Start-Up

Upon a successful detection and classification process, power is applied to the load through a controlled start-up

mechanism.

During this period, inrush current is limited to ILIM for a duration of TLIM (as specified in the table Port Real-Time

Protection), which allows PD load to charge and allows a steady state of power condition.

4.5

Over-Load Detection and Port Shut-Down

After power-up, the PSE manager automatically initializes its internal protection mechanisms. These mechanisms are

used to monitor and disconnect power from the PD when extreme conditions occur. These conditions include over-

current or short ports terminals scenarios.

4.6

Disconnect Detection

The managers support the DC disconnect function as per IEEE 802.3 standards. This mechanism continuously

monitors load current and disconnects power according to IUDL, TMPDO, and TMPS parameters as specified in Port

Real-Time Protection.

4.7

IC Thermal Monitoring

The managers contains a thermal sensor that is sampled by the controller so that the manager die temperature is

monitored at all times. To protect the PSE manager from damage, the system ports are disconnected before damage

can occur.

A temperature alarm threshold can be set by the controller to send interrupt indication by the xINT_OUT pin before

ports are disconnected. The temperature can be read and monitored by the host as well if required.

4.8

Over-Temperature Protection

In addition to the die thermal sensor, there are thermal sensors on each MOSFET that continuously monitors each

port main MOSFETs junction temperature and shuts down the port load power when the temperature exceeds the

threshold.

4.9

voltage thresholds.

4.10

2-Pair Ports

Operation modes include the following:

• PoE Type 1/2 class 0–4 (up to 30 W)

4.11

Port Power Limit

Port power limit (PPL) is used to configure port power limit. When a port exceeds the power limit, it gets disconnected

automatically.

PD39208

Application Information

Datasheet

DS00003555B-page 16