LTC4257-1 Linear Technology, LTC4257-1 Datasheet - Page 4

• Manufacturer Part Number: LTC4257-1
• Description: Power over Ethernet Interface Controller with Dual Current Limit
• Manufacturer: Linear Technology

LTC4257-1
4
TYPICAL PERFOR A CE CHARACTERISTICS
0.5
0.4
0.3
0.2
0.1
0
3
2
1
0
4
3
2
1
0
–40
0
0
Input Current vs Input Voltage
25k Detection Range
Power Good Output Low Voltage
vs Current
Input Current vs Input Voltage
T
EXCLUDES ANY LOAD CURRENT
T
T
A
A
A
= 25 C
= 25 C
= 25 C
–2
2
–45
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
CURRENT (mA)
–4
4
–50
–6
6
–55
W
–8
8
42571 G04
42571 G07
4357 G01
U
–10
–60
10
V1:
V2:
120
50
10
26
25
24
22
90
60
30
40
30
20
28
27
23
0
0
–2
–1
0
0
Input Current vs Input Voltage
Signature Resistance
vs Input Voltage
V
LTC4257-1 ONLY
RESISTANCE =
DIODES: S1B
T
V
T
T
A
OUT
A
IN
A
= 25 C
= 25 C
= 25 C
= 0V
–10
Leakage Current
–3
–4
LTC4257-1 + 2 DIODES
V
OUT
INPUT VOLTAGE (V)
–20
INPUT VOLTAGE (V)
20
CLASS 3
CLASS 2
CLASS 1
CLASS 0
CLASS 4
PIN VOLTAGE (V)
V
I
–5
–6
=
–30
V2 – V1
IEEE LOWER LIMIT
I
IEEE UPPER LIMIT
2
– I
1
–40
–7
–8
40
–50
–10
42571 G05
42571 G02
–9
42571 G08
–60
60
11.0
10.0
12.0
11.5
10.5
400
300
200
100
9.0
9.5
–1
–2
1
2
0
–40
–12
–40
Input Current vs Input Voltage
Normalized UVLO Threshold
vs Temperature
Current Limit vs Input Voltage
CLASS 1 OPERATION
APPLICABLE TO TURN-ON
AND TURN-0FF THRESHOLDS
–20
–14
–45
INPUT VOLTAGE (V)
TEMPERATURE ( C)
INPUT VOLTAGE (V)
0
–40 C
–40 C
85 C
85 C
–16
–40 C
85 C
20
–50
HIGH CURRENT MODE
LOW CURRENT MODE
–18
40
–55
60
–20
42571 G03
42571 G09
42571 G06
42571fa
80
–60
–22