LTC4274_15 Datasheet, PDF (1/28 Pages) Linear Technology – Single PoE PSE Controller

LTC4274
Single PoE+ PSE Controller
FEATURES
nn _{Compliant with IEEE 802.3at Type 1 and 2}
nn _{0.34Ω Total Channel Resistance}
nn _{130mW/Port at 600mA}
nn _{Advanced Power Management}
nn _{8-Bit Programmable Current Limit (ILIM)}
nn _{7-Bit Programmable Overload Currents (ICUT)}
nn _{Fast Shutdown}
nn _{14.5-Bit Port Current/Voltage Monitoring}
nn _{2-Event Classification}
nn _{Very High Reliability 4-Point PD Detection}
nn _{2-Point Forced Voltage}
nn _{2-Point Forced Current}
nn _{High Capacitance Legacy Device Detection}
nn _{LTC4259A-1 and LTC4266 SW Compatible}
nn _{1MHz I}²_{C Compatible Serial Control Interface}
nn _{Midspan Backoff Timer}
nn _{Supports Proprietary Power Levels Above 25W}
nn _{Available in 38-Pin 5mm × 7mm QFN Package}
APPLICATIONS
nn _{PSE Switches/Routers}
nn _{PSE Midspans}
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT and LTPoE++ are trademarks of Linear Technology Corporation. All other trademarks
are the property of their respective owners.
DESCRIPTION
The LTC^®4274 is a single power sourcing equipment con-
troller designed for use in IEEE 802.3 Type 1 and Type 2
(high power) compliant Power over Ethernet systems.
External power MOSFETs enhance system reliability and
minimize channel resistance, cutting power dissipation and
eliminating the need for heatsinks even at Type 2 power
levels. External power components also allow use at very
high power levels while remaining otherwise compatible
with the IEEE standard. 80V-rated port pins provide robust
protection against external faults.
The LTC4274 includes advanced power management
features, including current and voltage readback and pro-
grammable I_CUT and I_LIM thresholds. Available C libraries
simplify software development; an optional AUTO pin mode
provides fully IEEE-compliant standalone operation with
no software required. Proprietary 4-point PD detection
circuitry minimizes false PD detection while supporting
legacy phone operation. Midspan operation is supported
with built-in 2-event classification and backoff timing.
Host communication is via a 1MHz I²C serial interface.
The LTC4274 is available in a 5mm × 7mm QFN package
that significantly reduces board space compared with
competing solutions.
TYPICAL APPLICATION
Complete Ethernet High Power Source
10Ω
3.3V
+ ^SMAJ5.0A
10µF
10Ω
+
C_BULK
–54V
SMAJ58A
TVSBULK
AD0 AD1 AD2 AD3
V_DD
0.1µF
SCL SDAIN SDAOUT INT
AUTO
DGND
LTC4274
MSD
RESET
AGND
MID
1µF
100V
V_EE SENSE GATE OUT ^SHDN
0.22µF
100V
S1B
S1B
–54V
PORT
4274 TA01
For more information www.linear.com/LTC4274
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