LTC4266 Datasheet, PDF (1/30 Pages) Linear Technology – Quad IEEE 802.3at Power over Ethernet Controller

FEATURES
n _{Four Independent PSE Channels}
n _{Compliant with IEEE 802.3at Type 1 and 2}
n _{0.34Ω Total Channel Resistance}
130mW/Port at 600mA
n _{Advanced Power Management}
8-Bit Programmable Current Limit (I_LIM)
7-Bit Programmable Overload Currents (I_CUT)
Fast Shutdown of Preselected Ports
14.5-Bit Port Current/Voltage Monitoring
2-Event Classification
n _{Very High Reliability 4-Point PD Detection:}
2-Point Forced Voltage
2-Point Forced Current
n _{High Capacitance Legacy Device Detection}
n _{LTC4259A-1 and LTC4258 Pin and SW Compatible}
n _{1MHz I}²_{C Compatible Serial Control Interface}
n _{Midspan Backoff Timer}
n _{Supports Proprietary Power Levels Above 25W}
n _{Available in 38-Pin 5mm × 7mm QFN and 36-Pin}
SSOP Packages
APPLICATIONS
n _{High Power PSE Switches/Routers}
n _{High Power PSE Midspans}
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LTC4266
Quad IEEE 802.3at Power
over Ethernet Controller
DESCRIPTION
The LTC^®4266 is a quad PSE controller 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 resis-
tance, 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 LTC4266 includes advanced power management
features, including current and voltage readback and pro-
grammable I_CUT and I_LIM thresholds. Available C libraries
simplify power-management 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 detec-
tion 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 LTC4266 is available in a 5mm × 7mm QFN package
that significantly reduces board space compared with
competing solutions. A legacy-compatible 36-pin SSOP
package is also available.
TYPICAL APPLICATION
Complete 4-Port Ethernet High Power Source
3.3V
0.1µF
SCL
SDAIN
INT SHDN1 SHDN2 SHDN3 SHDN4 V_DD
AUTO MSD RESET MID
SDAOUT
AD0
AD1
LTC4266
AD2
AD3 _{DGND AGND VEE SENSE1 GATE1 OUT1 SENSE2 GATE2 OUT2 SENSE3 GATE3 OUT3 SENSE4 GATE4 OUT4}
0.22µF 100V
S1B
×4
×4
–50V
SMAJ58A
1µF
S1B
×4
–50V
PORT1
PORT2
PORT3
PORT4
4266 TA01
4266fb
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