LTC4257IS8 Linear Technology, LTC4257IS8 Datasheet - Page 4

• Manufacturer Part Number: LTC4257IS8
• Description: IC CONTROLLER POE INTERFAC 8SOIC
• Manufacturer: Linear Technology
• Type: Power over Ethernet Switch (PoE)r

Specifications of LTC4257IS8

• Applications: IP Phones, Power over LAN, Network Routers and Switches
• Internal Switch(s): Yes
• Current Limit: 350mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

LTC4257
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
Input Current vs Input Voltage
25k Detection Range
0
Input Current vs Input Voltage
Power Good Output Low Voltage
vs Current
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
4357 G02
4257 G04
4257 G07
U
–10
–60
10
V1:
V2:
120
50
40
30
20
10
26
24
22
90
60
30
28
27
25
23
0
0
–2
–1
0
Input Current vs Input Voltage
0
Signature Resistance
vs Input Voltage
V
T
RESISTANCE =
DIODES: S1B
T
V
T
OUT
A
A
IN
A
LTC4257 ONLY
= 25°C
= 25°C
= 25°C
= 0V
–10
Leakage Current
–3
–4
V
LTC4257 + 2 DIODES
INPUT VOLTAGE (V)
OUT
–20
INPUT VOLTAGE (V)
20
CLASS 3
CLASS 2
CLASS 1
CLASS 0
CLASS 4
∆V
∆I
PIN VOLTAGE (V)
–5
–6
=
–30
V2 – V1
IEEE LOWER LIMIT
I
IEEE UPPER LIMIT
2
– I
1
–40
–7
–8
40
–50
–10
–9
42571 G09
4257 G05
4257 G01
–60
60
12.0
11.5
11.0
10.5
10.0
375
365
355
345
335
325
9.0
9.5
–2
–1
2
1
0
–40
–12
–40
Current Limit vs Input Voltage
Input Current vs Input Voltage
Normalized UVLO Threshold
vs Temperature
CLASS 1 OPERATION
APPLICABLE TO TURN-ON
AND TURN-0FF THRESHOLDS
V
OUT
–20
= V
–14
–45
IN
–40°C
85°C
+ 5V
TEMPERATURE (°C)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
0
–40°C
85°C
25°C
–16
20
–50
–18
40
–55
60
–20
4257 G03
4257 G09
4257 G06
80
4257fb
–60
–22