M1

C

OUT

D

VC1

GATE

V

C

CS

CTL

V

B

V

SS

C

IN

R

CTL

C

CTL

CLS

DEN

FRS

T2P

R

T2P-OUT

Type2PSE

Indicator

V

B

TLV431

R

OB

C

IZ

V

OUT

PAD

GAT2

M2

D

CL

C

CL

C

C

M4

M3

R

T2P

D

A

R

APD1

N/CORPPD

APD

R

DT

L

OUT

L

VC

T1

C

IO

D

VC2

Optional

Interface

V

T2P-OUT

TPS23754

TPS23754-1

TPS23756

www.ti.com

SLVS885D – OCTOBER 2008 – REVISED DECEMBER 2009

High Power/High Efficiency PoE Interface and DC/DC Controller

1

FEATURES

The TPS23754/6 supports a number of input voltage

2

•

Powers up to 30 W (input) PDs

ORing options including highest voltage, external

•

DC/DC Control Optimized for Isolated

adapter preference, and PoE preference. These

Converters

features allow the designer to determine which power

•

Supports High-efficiency Topologies

source will carry the load under all conditions.

•

Complete PoE Interface

The

PoE

interface

features

the

new

extended

•

Enhanced Classification per IEEE 802.3at with

hardware classification necessary for compatibility

Status Flag

with high-power midspan power sourcing equipment

(PSE) per IEEE 802.3at. The detection signature pin

•

Adapter ORing Support

can also be used to force power from the PoE source

•

Programmable Frequency with

off. Classification can be programmed to any of the

Synchronization

defined types with a single resistor.

•

Robust 100 V, 0.5

Ω Hotswap MOSFET

The dc/dc controller features two complementary gate

•

–40°C to 125°C Junction Temperature Range

drivers with programmable dead time. This simplifies

design

of

active-clamp

forward

converters

or

•

Industry Standard PowerPAD™ TSSOP-20

optimized

gate

drive

for

highly-efficient

flyback

topologies. The second gate driver may be disabled if

APPLICATIONS

desired for single MOSFET topologies. The controller

•

IEEE 802.3at Compliant Devices

also features internal softstart, bootstrap startup

•

Video and VoIP Telephones

source, current-mode compensation, and a 78%

•

RFID Readers

maximum

duty

cycle.

A

programmable

and

synchronizable oscillator allows design optimization

•

Multiband Access Points

for efficiency and eases use of the controller to

•

Security Cameras

upgrade existing power supply designs. Accurate

programmable

blanking,

with

a

default

period,

DESCRIPTION

simplifies

the

usual

current-sense

filter

design

trade-offs.

The TPS23754/6 is a combined Power over Ethernet

(PoE)

powered

device

(PD)

interface

and

The TPS23754 has a 15 V converter startup while the

current-mode dc/dc controller optimized specifically

TPS23756

has

a

9

V

converter

startup.

The

for isolated converters. The PoE interface supports

TPS23754-1 replaces the PPD pin with a no-connect

the IEEE 802.3at standard.

for increased pin spacing.

Figure 1. High Efficiency Converter Using TPS23754

1

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.

2

PowerPAD is a trademark of Texas Instruments.

PRODUCTION DATA information is current as of publication date.

Copyright © 2008–2009, Texas Instruments Incorporated

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.