TPS2378 IEEE 802.3at PoE High-Power PD Interface

1 Features

• IEEE 802.3at Type-2 Hardware Classification with Status Flag
• Adapter Priority Input
• DC/DC Converter Enable
• Robust 100 V, 0.5-Ω Hotswap MOSFET
• Operating Current up to 850 mA
• 1-A (Typical) Operating Current Limit
• 15 kV and 8 kV System-level ESD Capability
• PowerPAD™ HSOP Package

2 Applications

• IEEE 802.3at-compliant Devices
• Video and VoIP Telephones
• Multiband Access Points
• Security Cameras
• Pico-base Stations
• Forced, Four-Pair, High Power Devices (SLVA625)

3 Description

This 8-pin integrated circuit contains all of the features needed to implement an IEEE802.3at type-2 powered device (PD). The low 0.5-Ω internal switch resistance, combined with the enhanced thermal dissipation of the PowerPAD™ package, enables this controller to continuously handle up to 0.85 A. The TPS2378 features an auxiliary power detect (APD) input, providing priority for an external power adapter. It also features a 100-V pass transistor, 140-mA inrush current limiting, type-2 indication, auto-retry fault protection, and an open-drain power-good output.

1. For all available packages, see the orderable addendum at the end of the data sheet.

Typical Application Circuit

4 Revision History

Changes from B Revision (November 2012) to C Revision

• Added ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information section Go
• Deleted Detailed Pin Description section. Go
• Deleted CBD Pin Interface sectionGo
• Deleted APD Pin Divider Network, R_APD1, R_APD2 sectionGo

Changes from A Revision (March 2012) to B Revision

• Added Application: Forced, Four-Pair, High Power Devices (SLVA625)Go
• Added Note 1 to the ELECTRICAL CHARACTERISTICS tableGo
• Added section: Forced, Four-Pair, High Power PoE Go
• Changed Table 2, From: POWER ≤ 12.95W To: POWER ≤ 13W, From: POWER > 12.95W To POWER > 13W, and PD INPUT POWER (max) From: 12.95 W To 13W Go
• Changed Table 2, PSE Output Power for 802.3at (Type 2) From: 36W to 30WGo
• Changed text in the Detection section From: "( ΔV / ΔI ) between 23.75 kΩ and 26.25 kΩ at the PI." To: "( ΔV / ΔI ) between 23.7 kΩ and 26.3 kΩ at the PI." Go
• Added text to the Startup and Converter Operation section: "Additional loading applied between V_VDD and V_RTN during the inrush state may prevent successful PD and subsequent converter start up."Go
• Changed text in the Detection Resistor, R_DEN section From: "R_DEN between 23.75 kΩ and 26.25 kΩ, or 25 kΩ ± 5%. " To: "R_DEN between 23.7 kΩ and 26.3 kΩ, or 25 kΩ ± 5%."Go

Changes from * Revision (March 2012) to A Revision

• Changed the Inrush termination MAX value From: 100% To: 99%Go