1.2

Detection and Classification

The PD69201 signature detection is IEEE 802.3at-compliant. Pre-standard or legacy detection may also be enabled.

Detection is executed in three levels to guarantee power delivering to a valid PD.

Following a successful detection, the PD69201 generates two classification events per the IEEE 802.3at standard.

Figure 1-3. Detection and Classification

1.3

Port Start-Up

Upon successful detection and classification, power is applied via a controlled start-up mechanism.

As defined by IEEE 802.3at, during the startup period, the current is limited to 425 mA for a duration of 65 ms,

allowing the PD's capacitors to charge to the steady state power condition.

1.4

Over-Load and Short-Circuit Protection

After successful power-up, the PD69201 initializes its internal protection mechanism that monitors and disconnects

power from the port in cases of over-current or short circuit, as specified by IEEE 802.3af/at.

1.5

Maintain Power Signature (MPS)

The no-load function detects if a PD is still connected to the port by measuring the port current over time and

comparing it to current and time thresholds.

1.6

Over-Temperature Protection

A thermal sensor is located inside the PD69201.

In the case of an over-temperature event, the port will be turned off.

PD69201

Functional Descriptions

Datasheet

DS00003454D-page 10