Introduction

The PD77728 device is a part of Microchip’s seventh generation IEEE® 802.3bt compliant Power over Ethernet(PoE) Power Sourcing Equipment (PSE) family. This device is a fully integrated 8-port PoE manager with integrated Field Effect Transistor (FET) switches and current sense resistors. Up to 12 devices can be cascaded to provide 48 4-pair ports. The device is available in a 56-pin 8 mm × 8 mm QFN package.

Features

The PD77728 device and PD77728 based PSE have the following key features:

• Supported Standards

– IEEE 802.3bt

• Supported PD Types

– Type 1, Type 2 PDs (802.3af, 802.3at)

– Single-Signature (Type 1–4) PDs

– Dual-Signature (Type 3 and 4) PDs

– Pre-Standard (Legacy) 4-pair PDs

– Supports non-compliant and legacy PDs

• Four Operational Modes

– Controller mode in conjunction with PD77020 PSE Power Management Controller

– Semi-Auto mode

– Managed Auto mode

– Unmanaged Auto mode

• Cascade up to 12 devices to support 96 × 2-pair ports or 48 × 4-pair ports and any 4-pair/2-pair combination

• Device Features

– Stand-Alone device supports up to 8 × 2-pair ports or 4 × 4-pair ports and any 4-pair/2-pair combination

– Per-Port integrated FET, sense resistor, and port diode

– Total port resistance of 160 mΩ

– Device power dissipation ≤ 2W at full load

– Two power rails (55V and 3.3V) for maximum power efficiency

– Guaranteed 4-pair output power of > 90W

– Over Supply Signal (OSS) support

– AutoClass support

– Supports Fast and Perpetual PoE

– MarkHold function support

– Host Interface through I2C Communication

• Real-Time Protection (RTP)

• Measurements

– Per-Port voltage and current measurement

– Accurate main power measurement

• Surge

– Surge up to 2 kV without additional components per IEC61000-4-5-2014

– Surge compliance, ITU-T K.21, GR1089, IE61000-4-5-2014, EN55024

• Up to 10 kV per IEC61000-4-5-2014

• Up to 6 kV per ITU-T K.21

• Physical Characteristics

– Ambient temperature range –40 °C to 85 °C

– 56-pin 8 mm × 8 mm QFN package with thermal pad

– MSL3, RoHS compliant

Applications

The PD77728-based PSE has the following typical applications:

• Campus switches

• Switches and routers for enterprises, small and medium businesses, Small Office Home Office (SOHO), and

commercial markets

• Switches for lighting markets

• PoE injectors