FEATURES
nn Compliant with IEEE 802.3at Type 1 and 2
nn Low Power Dissipation
nn 0.25Ω Sense Resistance Per Channel
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 1MHz I2C Compatible Serial Control Interface
nn Midspan Backoff Timer
nn Supports 2-Pair and 4-Pair Output Power
nn Available in Multiple Power Grades
nn LTC4274A-1: LTPoE++™ 38.7W
nn LTC4274A-2: LTPoE++ 52.7W
nn LTC4274A-3: LTPoE++ 70W
nn LTC4274A-4: LTPoE++ 90W
nn LTC4274C: PoE 13W
nn Available in 38-Lead 5mm × 7mm QFN Package
APPLICATIONS
nn LTPoE++ PSE Switches/Routers
nn LTPoE++ PSE Midspans
nn IEEE 802.3at Type 1 PSE Switches/Routers
nn 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-RON 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 avail-
able in a 38-lead 5mm × 7mm QFN package.
TYPICAL APPLICATION
Complete Single-Port Ethernet High Power Source
3.3V 10Ω
+ SMAJ5.0A
10µF
10Ω
+
CBULK
–54V
SMAJ58A
TVSBULK
AD0 AD1 AD2 AD3
VDD
0.1µF
SCL SDAIN SDAOUT INT
AUTO
DGND
LTC4274AC
MSD
RESET
AGND
MID
1µF
100V
VEE SENSE GATE OUT SHDN
0.22µF
100V
S1B
S1B
PORT
4274AC TA01
–54V
For more information www.linear.com/LTC4274A
4274acfd
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