Datasheet
LTC4274A/LTC4274C
3
4274acfc
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
EE
Main PoE Supply Voltage AGND
– V
EE
For IEEE Type 1 Compliant Output
For IEEE Type 2 Compliant Output
For LTPoE
++
Compliant Output
l
l
l
45
51
54.75
57
57
57
V
V
V
Undervoltage Lockout AGND
– V
EE
l
20 25 30 V
V
DD
V
DD
Supply Voltage V
DD
– DGND
l
3.0 3.3 4.3 V
Undervoltage Lockout
l
2.2 V
Allowable Digital Ground Offset DGND
– V
EE
l
25 57 V
I
EE
V
EE
Supply Current (AGND
– V
EE
) = 55V
l
–2.4 –5 mA
I
DD
V
DD
Supply Current (V
DD
– DGND) = 3.3V
l
1.1 3 mA
Detection
Detection Current – Force Current First Point, AGND
– V
OUT
= 9V
Second Point, AGND
– V
OUT
= 3.5V
l
l
220
140
240
160
260
180
µA
µA
Detection Voltage – Force Voltage AGND
– V
OUT
, 5µA ≤ I
OUT
≤ 500µA
First Point
Second Point
l
l
7
3
8
4
9
5
V
V
Detection Current Compliance AGND
– V
OUT
= 0V
l
0.8 0.9 mA
V
OC
Detection Voltage Compliance AGND
– V
OUT
, Open Port
l
10.4 12 V
Detection Voltage Slew Rate AGND
– V
OUT
, C
PORT
= 0.15µF
l
0.01 V/µs
Minimum Valid Signature Resistance
l
15.5 17 18.5 k
Maximum Valid Signature Resistance
l
27.5 29.7 32 k
Classification
V
CLASS
Classification Voltage AGND
– V
OUT
, 0mA ≤ I
CLASS
≤ 50mA
l
16.0 20.5 V
Classification Current Compliance V
OUT
= AGND
l
53 61 67 mA
Classification Threshold Current Class 0 – 1
Class 1 – 2
Class 2 – 3
Class 3 – 4
Class 4 – Overcurrent
l
l
l
l
l
5.5
13.5
21.5
31.5
45.2
6.5
14.5
23
33
48
7.5
15.5
24.5
34.9
50.8
mA
mA
mA
mA
mA
V
MARK
Classification Mark State Voltage AGND
– V
OUT
, 0.1mA ≤ I
CLASS
≤ 10mA
l
7.5 9 10 V
Mark State Current Compliance V
OUT
= AGND
l
53 61 67 mA
Gate Driver
GATE Pin Pull-Down Current Port Off, V
GATE
= V
EE
+ 5V
Port Off, V
GATE
= V
EE
+ 1V
l
l
0.4
0.08 0.12
mA
mA
GATE Pin Fast Pull-Down Current V
GATE
= V
EE
+ 5V 30 mA
GATE Pin On Voltage V
GATE
– V
EE
, I
GATE
= 1µA
l
81214 V
Output Voltage Sense
V
PG
Power Good Threshold Voltage V
OUT
– V
EE
l
2 2.4 2.8 V
OUT Pin Pull-Up Resistance to AGND 0V ≤ (AGND
– V
OUT
) ≤ 5V
l
300 500 700 k
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, AGND = DGND, and V
DD
– DGND = 3.3V
unless otherwise noted. (Notes 3, 4)