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LTC4267 Datasheet, PDF (1/32 Pages) Linear Technology – Power over Ethernet IEEE 802.3af PD Interface with Integrated Switching Regulator | |||
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LTC4267
Power over Ethernet
IEEE 802.3af PD Interface with
Integrated Switching Regulator
FEATURES
â Complete Power Interface Port for IEEE 802®.3af
Powered Device (PD)
â Onboard 100V, 400mA UVLO Switch
â Precision Dual Level Inrush Current Limit
â Integrated Current Mode Switching Regulator
â Onboard 25kΩ Signature Resistor with Disable
â Programmable Classiï¬cation Current (Class 0-4)
â Thermal Overload Protection
â Power Good Signal
â Integrated Error Ampliï¬er and Voltage Reference
â Low Proï¬le 16-Pin SSOP and 3mm à 5mm DFN
Packages
U
APPLICATIO S
â IP Phone Power Management
â Wireless Access Points
â Security Cameras
â Power over Ethernet
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
802 is a registered trademark of Institute of Electrical and Electronics Engineers, Inc.
DESCRIPTIO
The LTC®4267 combines an IEEE 802.3af compliant Pow-
ered Device (PD) interface with a current mode switching
regulator, providing a complete power solution for PD
applications. The LTC4267 integrates the 25kΩ signature
resistor, classiï¬cation current source, thermal overload pro-
tection, signature disable and power good signal along with
an undervoltage lockout optimized for use with the IEEE-
required diode bridge. The precision dual level input current
limit allows the LTC4267 to charge large load capacitors
and interface with legacy PoE systems.
The current mode switching regulator is designed for
driving a 6V rated N-channel MOSFET and features pro-
grammable slope compensation, soft-start, and constant
frequency operation, minimizing noise even with light
loads. The LTC4267 includes an onboard error ampliï¬er
and voltage reference allowing use in both isolated and
nonisolated conï¬gurations.
The LTC4267 is available in space saving, low proï¬le
16-pin SSOP or DFN packages.
TYPICAL APPLICATIO
â48V
FROM
DATA PAIR
+
HD01
â
â48V
FROM
SPARE PAIR
+
HD01
â
Class 2 PD with 3.3V Isolated Power Supply
PA1133 SBM1040
VPORTP
PVCC
SMAJ58A
PWRGD
LTC4267
NGATE
0.1µF
SENSE
RCLASS
68.1â¦
1%
RCLASS ITH/RUN
VFB
SIGDISA PGND
VPORTN
POUT
10k
â¢
+
PVCC + 5µF
4.7µF
MIN
320µF
â¢
10k Si3440
PVCC
0.1â¦
470
6.8k
22nF
BA5516
PS2911
3.3V
1.5A
CHASSIS
100k
TLV431
60.4k
4267 TA01
4267f
1
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