LTC4290/LTC4271
8-Port PoE/PoE+
PSE Controller
FEATURES
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DESCRIPTION
The LTC
®
4290/LTC4271 chipset is an 8-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
BOM cost savings. The LTC4290/LTC4271 chipset delivers
lowest-in-industry heat dissipation by utilizing low-R
DS(ON)
external MOSFETs and 0.25Ω sense resistors.
Advanced power management features include per-port 12-
bit current monitoring ADCs, DAC-programmable current
limit, and versatile fast shut-down of preselected ports.
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
backoff timer. The LTC4290/LTC4271 includes an I
2
C serial
interface operable up to 1MHz.
L,
LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
and LTPoE++ is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
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Eight Independent PSE Channels
Compliant with IEEE 802.3at Type 1 and 2
Chipset Provides Electrical Isolation
Reduced BOM Cost
Eliminates up to 6 High Speed Opto-Couplers
Eliminates Isolated 3.3V Power Supply
Low Power Dissipation
0.25Ω Sense Resistance Per Channel
Very High Reliability 4-Point PD Detection
2-Point Forced Voltage
2-Point Forced Current
V
EE
and V
PORT
Monitoring
1 Second Rolling I
PORT
Averaging
Supports 2-Pair and 4-Pair Output Power
1MHz I
2
C Compatible Serial Control Interface
Available In a 40-Lead 6mm × 6mm (LTC4290)
and 24-Lead 4mm × 4mm (LTC4271) QFN Package
APPLICATIONS
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PoE PSE Switches/Routers
PoE PSE Midspans
TYPICAL APPLICATION
3.3V
0.1µF
GP0
GP1
MID
RESET
MSD
AUTO
INT
LTC4271
SCL
SDAIN
SDAOUT
AD0
AD1
AD2
AD3
AD6 DGND
V
DD33
CPD
100
3.3V
100
CND
DPD
100
3.3V
100
DND
CAP1
1µF
2nF 2kV
0.1µF
CPA
XIO0
XIO1
OUTn
GATEn
SENSEn
LTC4290
0.25
0.22µF
100V
S1B
PORTn
S1B
–54V
NO ISOLATION
REQUIRED ON
I
2
C INTERFACE
•
•
100
–54V
100
CNA
DPA
•
•
100
–54V
100
DNA
0.22µF
100V
OUT1
GATE1
S1B
PORT1
S1B
–54V
SENSE1
CAP2 V
EE
VSSK AGND
>47µF
1µF SYSTEM
BULK CAP
0.25
+
–54V
429071 TA01a
–54V
429071f
1
LTC4290/LTC4271
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 4)
(Note 1)
LTC4290
Supply Voltages
AGND – V
EE
........................................... –0.3V to 80V
VSSK (Note 7) ..................... V
EE
– 0.3V to V
EE
+ 0.3V
Digital Pins
XIOn ................................. V
EE
– 0.3V to CAP2 + 0.3V
Analog Pins
SENSEn, GATEn, OUTn ........ V
EE
– 0.3V to V
EE
+ 80V
CAP2 (Note 13) ....................... V
EE
–0.3V to V
EE
+ 5V
CPA, CNA, DPA, DNA ..............V
EE
– 0.3V to V
EE
+ 0.3
Operating Ambient Temperature Range
LTC4290I .............................................–40°C to 85°C
Junction Temperature (Note 2) ............................ 125°C
Storage Temperature Range .................. –65°C to 150°C
LTC4271
Supply Voltages
V
DD
– DGND ......................................... –0.3V to 3.6V
Digital Pins
SCL, SDAIN, SDAOUT,
INT, RESET, MSD,
ADn, AUTO,
MID, GPn ........................DGND – 0.3V to V
DD
+ 0.3V
Analog Pins
CAP1 (Note 13) ...........................–0.3V to DGND + 2V
CPD, CND, DPD, DND ......DGND – 0.3V to V
DD
+ 0.3V
Operating Ambient Temperature Range
LTC4271I..............................................–40°C to 85°C
Junction Temperature (Note 2) ............................ 125°C
Storage Temperature Range .................. –65°C to 150°C
429071f
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LTC4290/LTC4271
PIN CONFIGURATION
LTC4290
TOP VIEW
DNA
CNA
DPA
CPA
LTC4271
V
EE
V
EE
TOP VIEW
NC
NC
V
DD33
DND
AUTO
CAP1
18 SCL
17 SDAIN
25
DGND
16 SDAOUT
15
INT
14
RESET
13 DNC
7
NC
8
CPD
9 10 11 12
V
DD33
CND
DPD
MSD
AD0 1
AD1 2
AD2 3
AD3 4
AD6 5
MID 6
GP0
GP1
NC
40 39 38 37 36 35 34 33 32 31
V
EE
1
GATE1 2
OUT1 3
GATE2 4
OUT2 5
CAP2 6
GATE3 7
OUT3 8
GATE4 9
OUT4 10
11 12 13 14 15 16 17 18 19 20
XIO0
SENSE1
SENSE2
SENSE3
SENSE4
SENSE5
SENSE6
SENSE7
SENSE8
XIO1
41
VSSK
30 V
EE
29 GATE8
28 OUT8
27 GATE7
26 OUT7
25 AGND
24 GATE6
23 OUT6
22 GATE5
21 OUT5
NC
24 23 22 21 20 19
UF PACKAGE
24-LEAD (4mm
×
4mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JC
= 4°C/W
EXPOSED PAD (PIN 25) IS DGND, MUST BE SOLDERED TO PCB
UJ PACKAGE
40-LEAD (6mm
×
6mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JC
= 2°C/W
EXPOSED PAD (PIN 41) IS VSSK, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC4271IUF#PBF
LTC4290BIUJ#PBF
TAPE AND REEL
LTC4271IUF#TRPBF
LTC4290BIUJ#TRPBF
PART MARKING
4271
LTC4290BUJ
PACKAGE DESCRIPTION
24-Lead (4mm × 4mm) Plastic QFN
40-Lead (6mm × 6mm) Plastic QFN
25.5W
MAX PWR TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
429071f
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LTC4290/LTC4271
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. AGND – V
EE
= 54V and V
DD
– DGND = 3.3V unless otherwise noted.
(Notes 3 & 4)
SYMBOL PARAMETER
V
EE
Main PoE Supply Voltage
CONDITIONS
AGND – V
EE
For IEEE Type 1 Compliant Output
For IEEE Type 2 Compliant Output
AGND – V
EE
V
DD
– DGND
V
DD
– DGND
V
CAP1
– DGND
V
CAP2
– V
EE
(AGND – V
EE
) = 55V
V
EE
< 15V
(V
DD
– DGND) = 3.3V
First Point, AGND – V
OUTn
= 9V
Second Point, AGND – V
OUTn
= 3.5V
AGND – V
OUTn
, 5µA ≤ I
OUTn
≤ 500µA
First Point
Second Point
AGND – V
OUTn
= 0V
AGND – V
OUTn
, Open Port
AGND – V
OUTn
, C
PORT
= 0.15µF
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ELECTRICAL CHARACTERISTICS
MIN
45
51
20
3.0
TYP
MAX
57
57
UNITS
V
V
V
V
V
V
V
Undervoltage Lock-Out
V
DD
V
CAP1
V
CAP2
I
EE
R
EE
I
DD
Detection
Detection Current – Forced Current
Detection Voltage – Forced Voltage
V
DD
Supply Voltage
Undervoltage Lock-Out
Internal Regulator Supply Voltage
Internal Regulator Supply Voltage
V
EE
Supply Current
V
EE
Supply Resistance
V
DD
Supply Current
25
3.3
2.7
1.84
4.3
9
10
30
3.6
15
12
15
260
180
9
5
0.9
12
0.01
18.5
32
20.5
mA
kΩ
mA
µA
µA
V
V
mA
V
V/µs
kΩ
kΩ
V
mA
mA
mA
mA
mA
mA
V
mA
mA
mA
mA
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220
143
7
3
240
160
8
4
0.8
10.4
Detection Current Compliance
V
OC
Detection Voltage Compliance
Detection Voltage Slew Rate
Min. Valid Signature Resistance
Max. Valid Signature Resistance
Classification
V
CLASS
Classification Voltage
Classification Current Compliance
Classification Threshold Current
15.5
27.5
16.0
53
5.5
13.5
21.5
31.5
45.2
7.5
53
0.4
0.08
8
2
300
17
29.7
AGND – V
OUTn
, 0mA ≤ I
OUTn
≤ 50mA
V
OUTn
= AGND
Class 0-1
Class 1-2
Class 2-3
Class 3-4
Class 4-Overcurrent
AGND – V
OUTn
, 0.1mA ≤ I
CLASS
≤ 5mA
V
OUTn
= AGND
Port Off, V
GATEn
= V
EE
+ 5V
Port Off, V
GATEn
= V
EE
+ 1V
V
GATEn
= V
EE
+ 5V
V
GATEn
– V
EE
, I
GATEn
= 1µA
V
OUTn
– V
EE
0V ≤ (AGND – V
OUT
) ≤ 5V
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6.5
14.5
23
33
48
9
61
67
7.5
15.5
24.5
34.9
50.8
10
67
V
MARK
Classification Mark State Voltage
Mark State Current Compliance
Gate Driver
GATE Pin Pull-Down Current
GATE Pin Fast Pull-Down Current
GATE Pin On Voltage
Output Voltage Sense
V
PG
Power Good Threshold Voltage
OUT Pin Pull-Up Resistance to AGND
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0.12
30
12
2.4
500
14
2.8
700
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V
V
kΩ
429071f
4
LTC4290/LTC4271
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. AGND – V
EE
= 54V and V
DD
– DGND = 3.3V unless otherwise noted.
(Notes 3 & 4)
SYMBOL PARAMETER
V
CUT
Overcurrent Sense Voltage
CONDITIONS
V
SENSEn
– V
EE
,
hpen = 0Fh, cutn = D4h
hpen = 0Fh, cutn = E2h (Note 12)
Class 0, Class 3
Class 1
Class 2
Class 4
V
SENSEn
– V
EE
, hpen = 0Fh, limn = 80h,
(AGND – V
EE
) = 55V
V
EE
< V
OUT
< AGND – 29V
AGND – V
OUT
= 0V (Note 12)
hpen = 0Fh, limn = C0h,
(AGND – V
EE
) = 55V
V
OUT
– V
EE
= 0 – 10V
V
EE
+ 23V < V
OUT
< AGND – 29V
AGND – V
OUT
= 0V (Note 12)
V
EE
< V
OUT
< AGND – 10V,
(AGND – V
EE
) = 55V
Class 0 to Class 3
Class 4
V
SENSE
– V
EE
, rdis Bit = 0
V
SENSE
– V
EE
, rdis Bit = 1 (Note 12)
V
SENSEn
– V
EE
– V
LIM
(Note 12)
rdis Bit = 0
rdis Bit = 1
No Missing Codes, Reported as 14 Bits
V
SENSEn
– V
EE
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ELECTRICAL CHARACTERISTICS
MIN
89
152
89
26
49
152
TYP
94
159
94
28
52
159
MAX
99
168
99
30
55
168
UNITS
mV
mV
mV
mV
mV
mV
Overcurrent Sense in AUTO Pin Mode
V
LIM
Active Current Limit in 802.3af Compliant Mode
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102
25
106
112
50
mV
mV
Active Current Limit in High Power Mode
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204
102
25
212
106
225
115
50
mV
mV
mV
Active Current Limit in AUTO Pin Mode
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102
204
2.6
1.3
125
70
106
212
3.8
1.9
200
100
12
30.518
25.1
112
225
4.9
2.45
255
125
mV
mV
mV
mV
mV
mV
Bits
µV/LSB
ms/
Convert
Bits
mV/LSB
V
MIN
V
SC
DC Disconnect Sense Voltage
Short-Circuit Sense
Port Current Readback
Resolution
LSB Weight
Conversion Period
Port Voltage Readback
Resolution
LSB Weight
Digital Interface
V
ILD
Digital Input Low Voltage
I
2
C Input Low Voltage
V
IHD
Digital Input High Voltage
Digital Output Voltage Low
Internal Pull Up to V
DD
Internal Pull Down To DGND
ADn,
RESET, MSD,
GPn, AUTO, MID
(Note 6)
SCL, SDAIN (Note 6)
(Note 6)
I
SDAOUT
= 3mA, I
INT
= 3mA
I
SDAOUT
= 5mA, I
INT
= 5mA
ADn,
RESET, MSD,
GPn
AUTO, MID
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No Missing Codes, Reported as 14 Bits
V
SENSEn
– V
EE
12
5.8350
0.8
1.0
2.2
0.4
0.7
50
50
V
V
V
V
V
kΩ
kΩ
429071f
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