LTC4267CDHC-3 Datasheet, PDF (1/32 Pages) Linear Technology – Power over Ethernet IEEE 802.3af PD Interface with Integrated Switching Regulator

LTC4267
Power over Ethernet
IEEE 802.3af PD Interface with
Integrated Switching Regulator
FEATURES
■ _{Complete Power Interface Port for IEEE 802}^®_.3af
Powered Device (PD)
■ _{Onboard 100V, 400mA UVLO Switch}
■ _{Precision Dual Level Inrush Current Limit}
■ _{Integrated Current Mode Switching Regulator}
■ _{Onboard 25kΩ Signature Resistor with Disable}
■ _{Programmable Classification Current (Class 0-4)}
■ _{Thermal Overload Protection}
■ _{Power Good Signal}
■ _{Integrated Error Amplifier and Voltage Reference}
■ _{Low Profile 16-Pin SSOP and 3mm × 5mm DFN}
Packages
U
APPLICATIO S
■ _{IP Phone Power Management}
■ _{Wireless Access Points}
■ _{Security Cameras}
■ _{Power over Ethernet}
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
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, classification 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 amplifier
and voltage reference allowing use in both isolated and
nonisolated configurations.
The LTC4267 is available in space saving, low profile
16-pin SSOP or DFN packages.
TYPICAL APPLICATIO
Class 2 PD with 3.3V Isolated Power Supply
PA1133 SBM1040
–48V
FROM
DATA PAIR
+
HD01
–
–48V
FROM
SPARE PAIR
+
HD01
–
V_PORTP
P_VCC
SMAJ58A
PWRGD
LTC4267
NGATE
0.1µF
SENSE
R_CLASS
68.1Ω
1%
R_CLASS I_TH/RUN
V_FB
SIGDISA PGND
V_PORTN
P_OUT
10k
•
+
P_VCC ⁺ _5µF
4.7µF
MIN
320µF
• ^MIN
10k ^Si3440
P_VCC
0.1Ω
470
6.8k
22nF
BAS516
PS2911
3.3V
1.5A
CHASSIS
100k
TLV431
60.4k
4267 TA01
4267fc
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