RCLASS++ Voltages ....... –0.3V to 8V (and ≤ VPORT)
AUX Current ........................................................ ±1.4mA
T2P,
PWRGD Voltage ............................... –0.3V to 100V
T2P,
PWRGD Current ...............................................5mA
Operating Junction Temperature Range (Note 4)
LT4275AI/LT4275BI/LT4275CI..............–40°C to 85°C
LT4275AH/LT4275BH/LT4275CH ....... –40°C to 125°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec.).................. 300°C
pin conFiguraTion
TOP VIEW
IEEEUVLO
AUX
RCLASS
RCLASS++/NC*
GND
1
2
3
4
5
11
GND
10 VPORT
9 HSGATE
8 HSSRC
7 PWRGD
6
T2P/NC*
IEEEUVLO
AUX
RCLASS
RCLASS++/NC*
GND
1
2
3
4
5
TOP VIEW
10
9
8
7
6
VPORT
HSGATE
HSSRC
PWRGD
T2P/NC*
DD PACKAGE
10-LEAD (3mm
×
3mm) PLASTIC DFN
T
JMAX
= 150°C,
θ
JC
= 5°C/W
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB GND
MS PACKAGE
10-LEAD PLASTIC MSOP
T
JMAX
= 150°C,
θ
JC
= 45°C/W
* RCLASS++ is not connected in the LT4275B/C versions.
T2P
is not connected in the LT4275C version.
orDer inForMaTion
LEAD FREE FINISH
LT4275AIDD#PBF
LT4275AHDD#PBF
LT4275AIMS#PBF
LT4275AHMS#PBF
LT4275BIDD#PBF
LT4275BHDD#PBF
LT4275BIMS#PBF
LT4275BHMS#PBF
LT4275CIDD#PBF
LT4275CHDD#PBF
LT4275CIMS#PBF
LT4275CHMS#PBF
TAPE AND REEL
LT4275AIDD#TRPBF
LT4275AHDD#TRPBF
LT4275AIMS#TRPBF
LT4275AHMS#TRPBF
LT4275BIDD#TRPBF
LT4275BHDD#TRPBF
LT4275BIMS#TRPBF
LT4275BHMS#TRPBF
LT4275CIDD#TRPBF
LT4275CHDD#TRPBF
LT4275CIMS#TRPBF
LT4275CHMS#TRPBF
PART MARKING*
LGBS
LGBS
LTGBT
LTGBT
LGBV
LGBV
LTGBW
LTGBW
LGBX
LGBX
LTGBY
LTGBY
MAX PD
POWER
90W
90W
90W
90W
25.5W
25.5W
25.5W
25.5W
13W
13W
13W
13W
PACKAGE DESCRIPTION
10-Lead (3mm
×
3mm) Plastic DFN
10-Lead (3mm
×
3mm) Plastic DFN
10-Lead Plastic MSOP
10-Lead Plastic MSOP
10-Lead (3mm
×
3mm) Plastic DFN
10-Lead (3mm
×
3mm) Plastic DFN
10-Lead Plastic MSOP
10-Lead Plastic MSOP
10-Lead (3mm
×
3mm) Plastic DFN
10-Lead (3mm
×
3mm) Plastic DFN
10-Lead Plastic MSOP
10-Lead Plastic MSOP
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 125°C
–40°C to 85°C
–40°C to 125°C
–40°C to 85°C
–40°C to 125°C
–40°C to 85°C
–40°C to 125°C
–40°C to 85°C
–40°C to 125°C
–40°C to 85°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on nonstandard 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/
4275f
2
LT4275
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
SYMBOL
V
SIG
V
CLASS
V
MARK
PARAMETER
VPORT Operating Input Voltage
VPORT Signature Range
VPORT Classification Range
VPORT Mark Range
VPORT Aux Mode Range
Signature/Class Hysteresis Window
V
RESET
V
HSON
V
HSOFF
Reset Threshold
Hot Swap Turn-On Voltage
Hot Swap Turn-Off Voltage
Hot Swap On/Off Hysteresis Window
Supply Current
Supply Current
Supply Current During Classification
Supply Current During Mark Event
Signature and Classification
Signature Resistance
V
RCLS
V
SIG
(Note 2)
l
l
l
l
elecTrical characTerisTics
CONDITIONS
At VPORT Pin
At VPORT Pin
At VPORT Pin
At VPORT Pin, Preceded by V
CLASS
At VPORT Pin, AUX > V
AUXT
l
l
l
l
l
l
l
MIN
23
1.5
12.5
5.6
8
1.0
2.6
TYP
MAX
60
10
21
10
60
5.6
UNITS
V
V
V
V
V
V
V
V
V
V
V
V
IEEEUVLO
= 0V
IEEEUVLO
Open
IEEEUVLO
= 0V
IEEEUVLO
Open
l
l
l
l
l
35
27
30
21.5
3
31
22.5
37
29
VPORT = HSSRC = 57V
VPORT = 17.5V, RCLASS and RCLASS++ Open
V
MARK
l
l
l
2
0.4
0.5
23.7
5.8
1.32
24.4
8.3
1.40
0.7
1.1
2.2
25.2
11
1.43
2
6.1
4
6.3
5.8
6.5
8
0.8
0.8
5
5
18
10
200
690
840
990
22
27
18
mA
mA
mA
kΩ
kΩ
V
ms
V
µA
V
V
µA
µA
µA
V
µA
Hz
Signature Resistance During Mark Event V
MARK
(Note 2)
RCLASS/RCLASS++ Operating Voltage
–10mA ≥ I
RCLASS
≥ –36mA, V
CLASS
Classification Stability Time
VPORT Step to 17.5V, RCLASS = 34.8Ω
AUX Threshold
AUX Pin Hysteresis Current
T2P
Output Low
PWRGD Output Low
PWRGD Leakage Current
T2P
Leakage Current
AUX = 6.1V
1mA Load (LT4275A/LT4275B Only)
1mA Load
PWRGD = 60V
T2P
= 60V
V
HSGATE
– V
HSSRC
= 5V, V
PORT
> 42V, Out of Pin
V
HSGATE
– V
HSSRC
, 0µA to 10µA Load with Respect
to HSSRC
V
HSGATE
– V
HSSRC
= 5V
After PWRGD Valid, if LTPoE++ PSE Is Mutually
Identified
Analog/Digital Interface
V
AUXT
I
AUXH
l
l
l
l
l
l
Hot Swap Control
I
GPU
V
GOC
HSGATE Pull-Up Current
HSGATE Open Circuit Voltage
HSGATE Pull-Down Current
Timing
f
T2P
T2P
Frequency
l
l
l
l
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
Signature resistance specifications do not include resistance
added by the external diode bridge which can add as much as 1.1k to the
port resistance.
Note 3:
All voltages with respect to GND unless otherwise noted. Positive
currents are into pins; negative currents are out of pins unless otherwise
noted.
Note 4:
This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 150°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
4275f
3
LT4275
Typical perForMance characTerisTics
VPORT Current vs VPORT Voltage
25k Detection Range
0.5
T = –40°C
T = 25°C
T = 75°C
T = 125°C
VPORT VOLTAGE (V)
37
36
35
34
33
32
31
0
0
2
4
6
VPORT VOLTAGE (V)
8
10
4275 G01
VPORT Hot Swap Thresholds
IEEEUVLO
= 0V
Hot Swap ON
SUPPLY CURRENT (mA)
1.5
2.0
Supply Current During Power-On
T = –40°C
T = 25°C
T = 75°C
T = 125°C
0.4
VPORT CURRENT (mA)
0.3
1.0
0.2
0.1
0.5
Hot Swap OFF
0
30
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
35
40
45
50
VPORT VOLTAGE (V)
55
60
4275 G03
4275 G02
Signature Resistance
vs Input Voltage
26.25
T = –40°C
T = 25°C
T = 75°C
T = 125°C
VPORT VOLTAGE (V)
29.0
VPORT Hot Swap Thresholds
IEEEUVLO
= FLOAT
Hot Swap ON
VPORT VOLTAGE (V)
Hot Swap OFF
–25
0
25
50
75
TEMPERATURE (°C)
100
125
5.6
5.1
4.6
4.1
3.6
3.1
Reset Threshold
SIGNATURE RESISTANCE (k )
25.75
27.5
25.25
26.0
24.75
24.5
24.25
23.0
23.75
1
3
5
7
VPORT VOLTAGE (V)
9
4275 G04
21.5
–50
2.6
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
4275 G05
4275 G06
PWRGD,
T2P
Output Low
Voltage vs Current
4
T = –40°C
T = 25°C
T = 75°C
T = 125°C
VPORT VOLTAGE (V)
12.5
VPORT Classification Thresholds
DETECT OR MARK TO CLASS
CLASS TO MARK
T2P
FREQUENCY (Hz)
990
940
890
840
790
740
T2P
Frequency
3
VOLTAGE (V)
12.0
11.5
2
11.0
1
10.5
0
0
1
2
3
CURRENT (mA)
4
5
4275 G07
10.0
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
690
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
4275 G08
4275 G09
4275f
4
LT4275
pin FuncTions
IEEEUVLO
(Pin 1):
Hot Swap Turn-on Threshold Level
Control. Connect to ground for IEEE compliant turn-on
and turn-off (UVLO) voltage thresholds. Leave open for
lower turn-on and turn-off voltage thresholds.
AUX (Pin 2):
Auxiliary Sense. Assert AUX via a resistive
divider from the auxiliary power input to set the voltage
at which the auxiliary supply takes over. Asserting AUX
pulls down HSGATE, disconnects the signature resistor,
disables classification and floats the PWRGD pin. The
AUX pin sinks I
AUXH
when below its threshold voltage of
V
AUXT
to provide hysteresis. Tie to GND when not used.
RCLASS (Pin 3):
Programmable PoE Classification Resis-
tor. See Table 1.
RCLASS++ (Pin 4, LT4275A Only):
Programmable
LTPoE++ Classification Resistor. This pin is not connected
on the LT4275B/LT4275C. See Table 1.
GND (Pin 5):
Ground Pin. Must be soldered to PCB GND.
T2P
(Pin 6, LT4275A/LT4275B Only):
PSE Type Indica-
tor, Open-Drain Output.
T2P
floats for a 13W PSE.
T2P
pulls down for a 25.5W PSE.
T2P
pulls down at f
T2P
with
a 50% (typical) duty cycle to indicate the presence of an
LTPoE++ PSE.
T2P
is valid after PWRGD is active. This pin
is not connected on the LT4275C. See the Applications
Information section for behavior when using the AUX pin.
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