LINER LTC4274

LTC4274
Single IEEE 802.3at Power Over Ethernet Controller
FEATURES
DESCRIPTION
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The LTC ®4274 is a single Power Sourcing Equipment (PSE)
controller designed for use in IEEE 802.3 Type 1 and Type 2
(high power) compliant Power over Ethernet (PoE) systems.
Compliant with IEEE 802.3at Type 1 and 2
Supports Proprietary Very High Power Up to 50W
0.34Ω Total Channel Resistance
130mW at 600mA
Advanced Power Management
8-Bit Programmable Current Limit (ILIM)
7-Bit Programmable Overload Currents (ICUT)
Fast Shutdown
14.5-Bit Port Current/Voltage Monitoring
2-Event Classification
Very High Reliability 4-Point PD Detection:
2-Point Forced Voltage
2-Point Forced Current
High Capacitance Legacy Device Detection
LTC4259A-1 and LTC4266 SW Compatible
1MHz I2C Compatible Serial Control Interface
Midspan Backoff Timer
Available in 38-Pin 5mm × 7mm QFN Package
The LTC4274 is also a good choice for proprietary PoE PSE
systems, which may require more power than the new IEEE
802.3at standard allows. The LTC4274 can source up to 50W
while otherwise remaining compatible with IEEE 802.3at.
The LTC4274 delivers lowest-in-industry heat dissipation by
utilizing a low RON external MOSFET and a 0.25Ω sense resistor, eliminating the need for expensive heat sinks. An external
MOSFET also provides a more robust solution compared to
an integrated MOSFET.
Advanced power management features include: selectable high
speed 9.5-bit (1kHz) or high resolution 14.5-bit current and
voltage readback, a 7-bit DAC for overcurrent threshold (ICUT ),
a unique nonlinear 8-bit programmable current limit (ILIM) and
versatile quick shutdown. PD Discovery uses a proprietary dualmode 4-point detection mechanism ensuring the best immunity
from false PD detection. Midspan PSEs are supported with
2-event classification and a two second backoff timer. Legacy
high-capacitance device detection is available. The LTC4274
includes an I2C serial interface operable up to 1MHz.
APPLICATIONS
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PoE PSE Switches/Routers
PoE PSE Midspans
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
Complete Ethernet High Power Source
3.3V
INT
SCL
SDAIN
SDAOUT
AD0
AD1
AD2
AD3
DGND AGND
SMAJ58A
SHDN
0.1μF
VDD
AUTO
MSD
RESET
MID
LTC4274
VEE SENSE
GATE OUT
1μF
100V
S1B
0.22μF
100V
PORT
–54V
4274 TA01
S1B
–54V
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LTC4274 Product Brief
BENEFITS
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Lowest Channel Resistance Eliminates Heat Sinks
First Fully IEEE 802.3at-Compliant Single PSE
LAYER 2 CLASSIFICATION (DATA LAYER)
IS INTENDED FOR ENDPOINT PSEs. USES
LINK LAYER DISCOVERY PROTOCOL (LLDP)
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Linear’s Experienced and Dedicated PoE Team
Linear Technology’s team provides timely technical
support and optimum performance at the lowest overall
cost with fastest time to market.
LAYER 1 CLASSIFICATION
(POWER LAYER) IS INTENDED
FOR MIDSPANS.
PSE
VOLTAGE
ON RANGE
CLASS EVENT #1
TRANSITION TO ON RANGE
VIA CLASS EVENT #3
CLASS EVENT #2
MARK EVENT #1
MARK EVENT #2
DETECT RANGE
CLASS RANGE
MARK RANGE
RESET RANGE
TIME
LTC4274 Voltage Probe During 2-Event Classification
LTC4274 Size Comparison
RELATED PARTS
PART NUMBER
PSE/PD
CHANNELS DESCRIPTION
PACKAGE
LTC4264
PD
1
Pre-Standard High Power PD PoE Interface Controller (35W)
4mm × 3mm DFN-12
LTC4265
PD
1
IEEE 802.3at High Power PD PoE+ Interface Controller (25.5W)
4mm × 3mm DFN-12
LTC4268-1
PD
1
Pre-Standard High Power PD PoE Interface Controller with Integrated Synchronous
Switching Regulator (35W)
7mm × 4mm DFN-32
LTC4269-1
PD
1
IEEE 802.3at High Power PD PoE+ Interface Controller with Integrated Synchronous
No-Opto Flyback Switching Regulator (25.5W)
7mm × 4mm DFN-32
LTC4269-2
PD
1
IEEE 802.3at High Power PD PoE+ Interface Controller with Integrated Synchronous
Forward Converter (25.5W)
7mm × 4mm DFN-32
LTC4278
PD
1
IEEE 802.3at High Power PD PoE+ Interface Controller with Integrated Synchronous
No-Opto Flyback Switching Regulator (25.5W), 12V Auxiliary Support
7mm × 4mm DFN-32
LTC4263-1
PSE
1
High Power IEEE 802.3af PSE Controller with Internal Switch
4mm × 3mm DFN-14
SO-14
LTC4266
PSE
4
Supports IEEE 802.3at Type 1 and Type 2 PDs, 0.34Ω Channel Resistance, Advanced
Power Management, High Reliability 4-Point PD Detection, Legacy Capacitance Detect
5mm × 7mm DFN-38
SSOP-36
INFO AND SAMPLES
• Visit http://www.linear.com/contact/ or call 1-800-4-LINEAR to find contact information for the sales office or distributor
near you.
• Visit http://www.linear.com/poe for more information about PoE and PoE+ products.
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Linear Technology Corporation
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LT 1009 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2009