LTC4274A Datasheet, PDF (1/30 Pages) Linear Technology – Single PoE/PoE+/LTPoE++ PSE Controller

FEATURES
n _{Compliant with IEEE 802.3at Type 1 and 2}
n _{Low Power Dissipation}
0.25Ω Sense Resistance Per Channel
n _{Very High Reliability 4-Point PD Detection}
2-Point Forced Voltage
2-Point Forced Current
n _{High Capacitance Legacy Device Detection}
n _{1MHz I}²_{C Compatible Serial Control Interface}
n _{Midspan Backoff Timer}
n _{Supports 2-Pair and 4-Pair Output Power}
n _{Available in Multiple Power Grades}
LTC4274A-1: LTPoE++™ 38.7W
LTC4274A-2: LTPoE++ 52.7W
LTC4274A-3: LTPoE++ 70W
LTC4274A-4: LTPoE++ 90W
LTC4274C: PoE 13W
n _{Available in 38-Lead 5mm × 7mm QFN Package}
APPLICATIONS
n _{LTPoE++ PSE Switches/Routers}
n _{LTPoE++ PSE Midspans}
n _{IEEE 802.3at Type 1 PSE Switches/Routers}
n _{IEEE 802.3at Type 1 PSE Midspans}
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
LTPoE++ are trademarks of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
LTC4274A/LTC4274C
Single PoE/PoE+/LTPoE++
PSE Controller
DESCRIPTION
The LTC^®4274A is a single Power Sourcing Equipment
(PSE) controller capable of delivering up to 90W of LTPoE++
power to a compatible LTPoE++ Powered Device (PD). A
proprietary detection/classification scheme allows mutual
identification between a LTPoE++ PSE and LTPoE++ PD
while remaining compatible and interoperable with existing
Type 1 (13W) and Type 2 (25.5W) PDs. The LTC4274A
feature set is a superset of the popular LTC4274. These
PSE controllers feature low-R_ON external MOSFETs and
0.25Ω sense resistors which are especially important at
the LTPoE++ current levels to maintain the lowest possible
heat dissipation.
The LTC4274C targets fully automatic PSE systems power-
ing Type 1 (up to 13W) PDs.
Advanced power management features include: a 14-bit
current monitoring ADC, DAC-programmable current limit,
and versatile quick port shutdown. PD Discovery uses
a proprietary dual-mode 4-point detection mechanism
ensuring excellent immunity from false PD detection.
The LTC4274A/LTC4274C includes an I²C serial interface
operable up to 1MHz.
The LTC4274A/LTC4274C is available in multiple power
grades, allowing delivered PD power of 13W, 25.5W, 38.7W,
52.7W, 70W and 90W. These controllers are available in a
38-lead 5mm × 7mm QFN package.
TYPICAL APPLICATION
Complete Single-Port Ethernet High Power Source
3.3V 0.1μF
SCL
INT
SDAIN
SDAOUT
AD0
AD1
AD2
AD3 _{DGND AGND}
SHDN
V_DD
LTC4274A/LTC4274C
V_EE SENSE GATE OUT
AUTO
MSD
RESET
MID
SMAJ58A
–54V
1μF
100V
S1B
S1B
–54V
0.22μF
100V
PORT
4274AC TA01
4274acfc
1