FEATURES

Integrated Power Interface Switch for IEEE

802.3af Powered Devices (PDs)

Provides PD Detection Signature

Provides PD Classification Signature

(Class 0−4)

Programmable Inrush Current Limit

Internal 0.3-Ω Low-Side FET

Interfaces to DC/DC Soft-Start for DC/DC

Enable

Internal Thermal Protection – Disconnects PD

Load

Minimal External Parts Count

8-Pin SOIC, 8-Pin TSSOP Packages

APPLICATIONS

VoIP Phones

Internet Appliances

Wireless LAN Access Points

Bluetooth Access Points

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 as voltage

measurement schemes for classification. Above 20-V

input, the classification current is shut off, reducing

internal power dissipation.

The TPS2370 drives an internal low-side FET for

control of the return side of the power path. The internal

FET is turned on when the input voltage reaches 40 V

and above. When the input voltage decreases, the FET

remains on until the input voltage drops to below 30 V.