LTC4257-1 Linear Technology, LTC4257-1 Datasheet - Page 15

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

APPLICATIO S I FOR ATIO
RJ45
RJ45
RJ45
U
1
2
3
6
4
5
7
8
1
2
3
6
4
5
7
8
1
2
3
6
4
5
7
8
TX
TX
RX
RX
TX
TX
RX
RX
TX
TX
RX
RX
+
–
+
–
+
–
+
–
+
–
+
–
SPARE
SPARE
SPARE
SPARE
SPARE
SPARE
U
+
–
+
–
+
–
OPTION 2: AUXILARY POWER INSERTED AFTER LTC4257-1 WITH SIGNATURE DISABLED
TRANSFORMER
TRANSFORMER
TRANSFORMER
ISOLATED
ISOLATED
ISOLATED
WALL
WALL
WALL
T1
T1
T1
OPTION 3: AUXILARY POWER APPLIED TO LTC4257-1 AND PD LOAD
W
OPTION 1: AUXILARY POWER INSERTED BEFORE LTC4257-1
+
38V TO 57V
–
+
–
+
–
Figure 9. Auxiliary Power Source for PD
38V TO 57V
TO PHY
TO PHY
TO PHY
U
~
~
~
~
~
~
~
~
~
~
~
~
DF01SA
DF01SA
DF01SA
DF01SA
DF01SA
DF01SA
BR1
BR2
BR1
BR2
BR1
BR2
+
–
+
–
+
–
+
–
+
–
+
–
S1B
D8
D3
SMAJ58A
TVS
D3
SMAJ58A
TVS
D3
SMAJ58A
TVS
4
4
4
V
V
V
LTC4257-1
IN
LTC4257-1
IN
LTC4257-1
IN
SIGDISA
V
V
V
GND
GND
GND
OUT
OUT
OUT
C14
0.1 F
100V
C14
0.1 F
100V
C14
0.1 F
100V
D10
S1B
8
5
8
7
5
8
5
BSS63
42571 F09
C1
C1
100k
100k
S1B
D10
S1B
D9
LOAD
PD
LOAD
PD
C1
LOAD
PD
LTC4257-1
15
42571fa