TPS23754_17 Datasheet, PDF (1/45 Pages) Texas Instruments – High-Power/High-Efficiency PoE Interface and DC-DC Controller

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TPS23754, TPS23754-1, TPS23756
SLVS885H – OCTOBER 2008 – REVISED OCTOBER 2015
TPS2375x High-Power/High-Efficiency PoE Interface
and DC-DC Controller
1 Features
• Powers up to 30-W (Input) PDs
• DC-DC Control Optimized for Isolated Converters
• Supports High-Efficiency Topologies
• Complete PoE Interface
• Enhanced Classification per IEEE 802.3at With
Status Flag
• Adapter ORing Support
• Programmable Frequency With Synchronization
• Robust 100-V, 0.5-Ω Hotswap MOSFET
• –40°C to 125°C Junction Temperature Range
• Industry Standard PowerPAD™ HTSSOP-20
2 Applications
• IEEE 802.3at Compliant Devices
• Video and VoIP Telephones
• RFID Readers
• Multiband Access Points
• Security Cameras
3 Description
The TPS23754 and TPS23756 devices have a
combined power-over-ethernet (PoE), powered-
device (PD) interface, and current-mode DC-DC
controller optimized specifically for isolated
converters. The PoE interface supports the IEEE
802.3at standard.
The TPS23754 and TPS23756 support a number of
input voltage ORing options including highest voltage,
external adapter preference, and PoE preference.
These features allow the designer to determine which
power source will carry the load under all conditions.
1
The PoE interface features the new extended
hardware classification necessary for compatibility
with high-power midspan power sourcing equipment
(PSE) per IEEE 802.3at. The detection signature pin
can also be used to force power from the PoE source
off. Classification can be programmed to any of the
defined types with a single resistor.
The DC-DC controller features two complementary
gate drivers with programmable dead time. This
simplifies the design of active-clamp forward
converters or optimized gate drive for highly-efficient
flyback topologies. The second gate driver may be
disabled if desired for single MOSFET topologies.
The controller also features internal soft start,
bootstrap start-up source, current-mode
compensation, and a 78% maximum duty cycle. A
programmable and synchronizable oscillator allows
design optimization for efficiency and eases use of
the controller to upgrade existing power supply
designs. Accurate programmable blanking, with a
default period, simplifies the usual current-sense filter
design trade-offs.
The TPS23754 device has a 15-V converter start-up
while the TPS23756 device has a 9-V converter start-
up. The TPS23754-1 replaces the PPD pin with a no-
connect for increased pin spacing.
Device Information⁽¹⁾
PART NUMBER
PACKAGE
BODY SIZE (NOM)
TPS23754
TPS23754-1
HTSSOP (20)
6.50 mm × 4.40 mm
TPS23756
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
High-Efficiency Converter Using TPS23754
D_A
R_APD1
Optional
Interface
DEN
CLS
N/C OR PPD
PAD
V_SS
APD
CTL
FRS
T2P
V_C
V_B
GATE
CS
GAT2
R_DT
R_T2P
L_VC
M1
C_C
M2
C_CL
D_CL
C_IO
C_IN
D_VC1
D_VC2
T1
M4
L_OUT
M3
C_OUT
V_B
R_CTL
C_CTL
R_OB
C_IZ
TLV431
V_OUT
R_T2P-OUT
V_T2P-OUT
Type 2 PSE
Indicator
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.