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.