LTC4270/LTC4271
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12-Port PoE/PoE /LTPoE
PSE Controller
FEATURES
DESCRIPTION
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12 Independent PSE Channels The LTC 4270/LTC4271 chipset is a 12-port power sourc-
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Compliant with IEEE 802.3at Type 1 and 2 ing equipment (PSE) controller designed for use in IEEE
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Chipset Provides Electrical Isolation 802.3at Type 1 and Type 2 (high power) compliant Power
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Reduced BOM Cost over Ethernet (PoE) systems. Transformer-isolated com-
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Eliminates up to 6 High Speed Opto-Couplers munication protocol replaces expensive opto-couplers
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Eliminates Isolated 3.3V Power Supply and complex isolated 3.3V supply resulting in significant
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Low Power Dissipation BOM cost savings. The LTC4270/LTC4271 chipset delivers
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0.25 Sense Resistance Per Channel lowest-in-industry heat dissipation by utilizing low-R
DS(ON)
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Very High Reliability 4-Point PD Detection external MOSFETs and 0.25 sense resistors.
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2-Point Forced Voltage
Advanced power management features include per-port
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2-Point Forced Current
12-bit current monitoring ADCs, DAC-programmable cur-
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V and V Monitoring
EE PORT
rent limit, and versatile fast shut-down of preselected ports.
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1 Second Rolling I Averaging
PORT
Advanced power management host software is available
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Supports 2-Pair and 4-Pair Output Power
under a no-cost license. PD discovery uses a proprietary
2
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1MHz I C Compatible Serial Control Interface
dual-mode 4-point detection mechanism ensuring excel-
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Available In Three Power Grades
lent immunity from false PD detection. Midspan PSEs
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A-Grade LTPoE 38.7W to 90W
are supported with 2-event classification and a 2 second
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B-Grade PoE 25.5W
2
backoff timer. The LTC4270/LTC4271 includes an I C
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C-Grade PoE 13W
serial interface operable up to 1MHz.
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Available In 52-Lead 7mm 8mm (LTC4270) and
The LTC4270/LTC4271 is available in multiple power
24-Lead 4mm 4mm (LTC4271) QFN Packages
grades allowing delivered PD power up to 90W.
APPLICATIONS
L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
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and LTPoE is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
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PoE PSE Switches/Routers
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PoE PSE Midspans
TYPICAL APPLICATION
3.3V 0.1F
V XIO0 XIO1
GP0 0.22F
DD33
LTC4270/LTC4271 FAMILY
S1B
100V
GP1
NO ISOLATION
OUTn
CPD CPA
PORTn
MID MAX
REQUIRED ON
2
100 100
I C INTERFACE RESET
LTC4270 DELIVERED
GATEn S1B
MSD
3.3V 54V
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GRADE ISOLATION LTPoE PoE PoE POWER
AUTO
0.25
100 100
INT
SENSEn 54V
A Transformer l l l 90W
CND CNA
LTC4271 LTC4270
SCL
0.22F
DPD DPA
B Transformer l l 25.5W
SDAIN
100V S1B
SDAOUT
100 100
C Transformer l 13W
OUT1 PORT1
3.3V 54V
AD0
AD1
100 100
S1B
GATE1
AD2
0.25
DND DNA
AD3
SENSE1 54V
10
AD6
DGND CAP1 AGND CAP2 V VSSK
EE
1F 0.1F
+
>47F
2nF 2kV 1F
SYSTEM
BULK CAP
54V 54V
42701fd
42701 TA01a
1
For more information www.linear.com/LTC4270LTC4270/LTC4271
ABSOLUTE MAXIMUM RATINGS LTC4270
(Note 1, Note 4)
Supply Voltages Operating Ambient Temperature Range
AGND V ........................................... 0.3V to 80V LTC4270I .............................................40C to 85C
EE
VSSK (Note 7) ..................... V 0.3V to V + 0.3V Junction Temperature (Note 2) ............................ 125C
EE EE
Digital Pins Storage Temperature Range ......................65 to 150C
XIOn ................................. V 0.3V to CAP2 + 0.3V
EE
Analog Pins
SENSEn, GATEn, OUTn ........ V 0.3V to V + 80V
EE EE
CAP2 (Note 13) ....................... V 0.3V to V + 5V
EE EE
CPA, CNA, DPA, DNA ..............V 0.3V to V + 0.3
EE EE
ABSOLUTE MAXIMUM RATINGS LTC4271
(Note 1)
Supply Voltages Analog Pins
V DGND ......................................... 0.3V to 3.6V CAP1 (Note 13) ...........................0.3V to DGND + 2V
DD
Digital Pins CPD, CND, DPD, DND ..........DGND 0.3 to V + 0.3
DD
SCL, SDAIN, SDAOUT, INT, RESET, MSD, ADn, AUTO, Junction Temperature (Note 2) ............................ 125C
MID, GPn ........................DGND 0.3V to V + 0.3V Storage Temperature Range ......................65 to 150C
DD
Operating Ambient Temperature Range
LTC4271I..............................................40C to 85C
42701fd
2
For more information www.linear.com/LTC4270