TPS2370

TPS2370 www.ti.com SLUS537C − AUGUST 2002 − REVISED MARCH 2004 IEEE 802.3af POWER INTERFACE SWITCH FOR POWER OVER ETHERNET (PoE) POWERED DEVICES FEATURES D Integrated Power Interface Switch for IEEE 802.3af Powered Devices (PDs) D Provides PD Detection Signature D Provides PD Classification Signature (Class 0−4) D Programmable Inrush Current Limit D Internal 0.3-Ω Low-Side FET D Interfaces to DC/DC Soft-Start for DC/DC Enable D Internal Thermal Protection – Disconnects PD Load D Minimal External Parts Count D 8-Pin SOIC, 8-Pin TSSOP Packages APPLICATIONS D VoIP Phones D Internet Appliances D Wireless LAN Access Points D Bluetooth Access Points TYPICAL APPLICATION DESCRIPTION Acting as an interface between the power sourcing equipment (PSE) and the powered device (PD), the TPS2370 performs all detection, classification, inrush current limiting, and switch FET control that is necessary for compliance with the IEEE 802.3af Standard. An internal 0.3-Ω FET provides maximum power delivery. As an additional feature, the TPS2370 interfaces with the enable/soft-start signal of a dc-to-dc converter, eliminating the need to have an accurate UVLO in the dc-to-dc converter. At low input voltages (1.8 V to 10 V), the TPS2370 draws less than 12 µA, allowing accurate sensing of the external 24.9-kΩ discovery resistor. At input voltages between 15 V and 20 V, an external resistor sets the level of current to be drawn during classification mode. TPS2370 is compatible with current as well...