TPS2371D

` Integrated Power Interface Switch for IEEE 802.3af Powered Devices (PDs)
` Precision UVLO Thresholds
` 20-ms UVLO Off-Time Delay
` Provides PD Detection Signature
` Provides PD Classification Signature (Class 0−4)
` Programmable Inrush Current Limit
` Internal 0.3- Low-Side FET
` Interfaces to DC/DC Soft-Start for DC/DC Enable
` Internal Thermal Protection Disconnects PD Load
` 8-Pin SOIC, 8-Pin TSSOP Packages

· VoIP Phones
· Internet Appliances
· Wireless LAN Access Points
· Bluetooth Access Points

(2) Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under  recommended operating conditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

Acting as an interface between the Power Source Equipment (PSE) and the Powered Device (PD), the TPS2371 performs all detection, class−ification, inrush current limiting, and switch FET control that is necessary for compatibility with Legacy/IEEE 802.3af Standard. The TPS2371 incorporates precision UVLO thresholds and hysteresis as well as a UVLO off-time delay to enable Legacy IEEE802.3af PoE compatibilty. An internal 0.3- FET provides maximum power delivery. As an additional feature, the TPS2371 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 TPS2371 draws less than 12 A, allowing accurate sensing of the external 24.9-k 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. TPS2371 is compatible with current as well as voltage measurement schemes for classification. Above 20-V input, the classification current is shut off, reducing internal power dissipation.