LTC4270/LTC4271
+
++
12-Port PoE/PoE /LTPoE
PSE Controller
FEATURES
DESCRIPTION
n
12 Independent PSE Channels
The LTC®4270/LTC4271 chipset is a 12-port power sourc-
ing equipment (PSE) controller designed for use in IEEE
802.3at Type 1 and Type 2 (high power) compliant Power
over Ethernet (PoE) systems. Transformer-isolated com-
munication protocol replaces expensive opto-couplers
and complex isolated 3.3V supply resulting in significant
BOMcostsavings.TheLTC4270/LTC4271chipsetdelivers
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Compliant with IEEE 802.3at Type 1 and 2
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Chipset Provides Electrical Isolation
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Reduced BOM Cost
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Eliminates up to 6 High Speed Opto-Couplers
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Eliminates Isolated 3.3V Power Supply
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Low Power Dissipation
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0.25Ω Sense Resistance Per Channel
lowest-in-industryheatdissipationbyutilizinglow-R
external MOSFETs and 0.25Ω sense resistors.
DS(ON)
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Very High Reliability 4-Point PD Detection
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2-Point Forced Voltage
Advanced power management features include per-port
12-bit current monitoring ADCs, DAC-programmable cur-
rentlimit,andversatilefastshut-downofpreselectedports.
Advanced power management host software is available
under a no-cost license. PD discovery uses a proprietary
dual-mode 4-point detection mechanism ensuring excel-
lent immunity from false PD detection. Midspan PSEs
are supported with 2-event classification and a 2 second
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2-Point Forced Current
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V
and V
Monitoring
EE
PORT
n
n
n
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1 Second Rolling I
Averaging
PORT
Supports 2-Pair and 4-Pair Output Power
2
1MHz I C Compatible Serial Control Interface
Available In Three Power Grades
™
n
++
A-Grade – LTPoE
B-Grade – PoE 25.5W
C-Grade – PoE 13W
38.7W to 90W
n
n
+
2
backoff timer. The LTC4270/LTC4271 includes an I C
serial interface operable up to 1MHz.
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Available In 52-Lead 7mm × 8mm (LTC4270) and
24-Lead 4mm × 4mm (LTC4271) QFN Packages
The LTC4270/LTC4271 is available in multiple power
grades allowing delivered PD power up to 90W.
All registered trademarks and trademarks are the property of their respective owners.
APPLICATIONS
n
PoE PSE Switches/Routers
PoE PSE Midspans
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TYPICAL APPLICATION
3.3V
0.1µF
V
DD33
XIO0
XIO1
OUTn
GP0
GP1
0.22µF
100V
LTC4270/LTC4271 FAMILY
S1B
PORTn
NO ISOLATION
REQUIRED ON
I C INTERFACE
CPD
CPA
MID
MAX
2
100Ω
100Ω
100Ω
–54V
RESET
MSD
AUTO
INT
•
•
•
LTC4270
GRADE ISOLATION LTPoE
DELIVERED
+
PoE PoE POWER
GATEn
S1B
–54V
3.3V
++
0.25Ω
100Ω
SENSEn
l
l
l
l
l
A
B
C
Transformer
Transformer
Transformer
90W
25.5W
13W
CND
DPD
CNA
DPA
LTC4271
LTC4270
SCL
SDAIN
SDAOUT
0.22µF
100V
l
S1B
100Ω
100Ω
100Ω
•
PORT1
OUT1
3.3V
–54V
100Ω
AD0
AD1
AD2
AD3
AD6
S1B
GATE1
0.25Ω
DND
DNA
–54V
SENSE1
VSSK
10Ω
V
EE
AGND CAP2
DGND
CAP1
1µF
0.1µF
+
>47µF
SYSTEM
1µF
2nF 2kV
BULK CAP
–54V
–54V
Rev E
42701 TA01a
1
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