TPS2371 Datasheet, PDF (1/14 Pages) Texas Instruments – LEGACY IEEE802.3AF COMPATIBLE POWER INTERFACE SWITCH FOR POWER OVER ETHERNET POWERED DEVICES

TPS2371
SLUS566A − JULY 2003 − REVISED NOVEMBER 2003
LEGACY/IEEE802.3af COMPATIBLE POWER INTERFACE SWITCH
FOR POWER OVER ETHERNET (PoE) POWERED DEVICES
FEATURES
D Integrated Power Interface Switch for IEEE
802.3af Powered Devices (PDs)
D Precision UVLO Thresholds
D 20-ms UVLO Off-Time Delay
D Provides PD Detection Signature
D Provides PD Classification Signature
(Class 0−4)
D Programmable Inrush Current Limit
D Internal 0.3-Ω Low-Side FET
D Interfaces to DC/DC Soft-Start for DC/DC
Enable
D Internal Thermal Protection – Disconnects
PD Load
D 8-Pin SOIC, 8-Pin TSSOP Packages
APPLICATIONS
D VoIP Phones
D Internet Appliances
D Wireless LAN Access Points
D Bluetooth Access Points
DESCRIPTION
Acting as an interface between the Power Source
Equipment (PSE) and the Powered Device (PD),
the TPS2371 performs all detection, class−
ification, inrush current limiting, and switch FET
control that is necessary for compatibility with
Legacy/IEEE 802.3af Standard. The TPS2371
incorporates precision UVLO thresholds and
hysteresis as well as a UVLO off-time delay to
enable Legacy IEEE802.3af PoE compatibilty. An
internal 0.3-Ω FET provides maximum power
delivery. As an additional feature, the TPS2371
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 TPS2371
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. TPS2371 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.
SIMPLIFIED APPLICATION DIAGRAM
V+
44 V
TO
57 V
SMAJ54A
V−
CBYPASS
CLIM
RDET
8
3
7
RLIM
TPS2371
1
RCLASS
6
2
4
5
Bluetooth is a trademark of the Bluetooth SIG, Inc.
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.
www.ti.com
CDCDCIN
CDEL
CSS
DC/DC _VREG
Converter/
Controller
Ethernet
Appliance
5V
UDG−03092
Copyright  1999 − 2003, Texas Instruments Incorporated
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