TPS2370

SLUS537C − AUGUST 2002 − REVISED MARCH 2004

IEEE 802.3af POWER INTERFACE SWITCH FOR

POWER OVER ETHERNET (PoE) POWERED DEVICES

FEATURES

802.3af Powered Devices (PDs)

(Class 0−4)

Enable

Load

APPLICATIONS

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-k

Ω 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.

TYPICAL APPLICATION

3

1

2

4

5

TPS2370

6

DC/DC

Converter/

Controller

8

Ethernet

Appliance

VREG

44 V

TO

57 V

V+

V−

SMAJ54A

24.9 k

W

RLIM

CSS

CDCDCIN

RCLASS

UDG−03057

0.1

mf

PRODUCTION DATA information is current as of publication date. Products

conform to specifications per the terms of Texas Instruments standard warranty.

Production processing does not necessarily include testing of all parameters.

PowerPAD

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Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments

semiconductor products and disclaimers thereto appears at the end of this data sheet.

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Copyright

 2002 − 2004, Texas Instruments Incorporated