1.1.1

Line Detection Generator

Upon request from the main control module, four different voltage levels are generated by the line detection

generator, ensuring robust AF/AT line detection functionality.

1.1.2

Classification Generator

Upon request from the main control module, the state machine applies a regulated class event and mark event

voltage to the ports, as required by the IEEE standard.

1.1.3

Current Limiter

This circuit continuously monitors the current of powered ports and limits the current to a specific value, according

to the pre-defined limits set by AF/AT and current_set pins. In cases where the current exceeds this specific level,

the system starts measuring the elapsed time. If this time period is greater than a preset threshold, the port is

disconnected.

1.1.4

Main MOSFET

Main power switching FET, used to control PoE current into the load.

1.1.5

Analog-to-Digital Converter (ADC)

A 10-bit analog-to-digital converter, used to convert analog signals into digital registers for the logic control module.

1.1.6

Power-on Reset (POR)

This circuit monitors the internal 3.3 VDC levels. If this voltage drops below specific thresholds, a reset signal is

generated and the PD69101s are reset.

1.1.7

Voltage Regulator

The voltage regulator generates 3.3 VDC and 5 VDC for the internal circuitry. These voltages are derived from the

1.1.8

CLK

CLK is an internal 8 MHz clock oscillator.

1.2

Application Information

The PD69101 performs IEEE 802.3af and IEEE 802.3at functionality as well as legacy (capacitor) and Cisco PD

detection, in addition to protections such as short circuit and dV/dT protection upon startup.

1.2.1

Line Detection

The line detection feature detects a valid AF or AT load, as specified in the AF/AT standard. The resistor value should

range from 19 KΩ to 26.5 KΩ. Line detection is based on four different voltage levels generated over the PD (the

load), as shown in the following figure.

PD69101

Functional Description

and its subsidiaries

Datasheet

DS00004280A-page 6