Datasheet
LTC4257-1
18
42571fb
APPLICATIO S I FOR ATIO
WUUU
•
1
•
•
5
4
•
1
3
2
RX
–
SPARE
–
6
RX
+
3
TX
–
2
TX
+
J2
IN
FROM
PSE
T1
RJ45
1
7
8
5
4
6
8
7
TXOUT
+
OUT
TO PHY
TXOUT
–
SPARE
+
RXOUT
+
RXOUT
–
16
14
15
11
9
10
C19
47pF
C13
470pF
V
OUT
+
V
OUT
–
R24
100k
R28
10k
R23
3.65k
1%
R13
30.1k
1%
R17
10k
R14
100k
R11
10k
R10
62k
R25
62k
R26
10k
R27
62k
C20
0.47µF
C21
0.1µF
NOTES: UNLESS OTHERWISE SPECIFIED
1. ALL RESISTORS ARE 5%
2. ALL CAPACITORS ARE 25V
3. SELECT R
CLASS
FOR CLASS 1-4 OPERATION. REFER
TO DATA SHEET APPLICATIONS INFORMATION SECTION
4. CONNECT TO CHASSIS GROUND
C4 TO C6: TDK C4532X5R0J107M
C2, C23: AVX 1808GC102MAT
D1, D7: MM3Z12VT1
D3: MMBD1505
D9 TO D12, D14 TO D16: DIODES INC., B1100
L1: COILCRAFT D01608C-472
T1: PULSE H2019
T2: PULSE PB2134
T3: PULSE PA0184
OSCAP SFSTt
ON
ENDLYMINENAB
LT1737CGN
R
OCMP
V
CC
R
CMPC
UVLO GATE
SGND PGND
V
C
FB
3V
OUT
I
SENSE
C22
680pF
0603
D8
BAT54
D5
B0540W
C17
3300pF
R15
0.22Ω
1/2W
1%
R4
10k
T2
SEPARATING
LINE
FOR GROUND
PLANE
T3
8
D7
12V
1
C12
0.1µF
50V
C10
4.7µF
35V
R16
330Ω
C16
0.1µF
50V
C23
1000pF
2kV
•
9
10
3
•
5
4
C18
1nF
R18
100Ω
Q6
Si7892DP
Q7
FMMT718
Q8
MMBT3904
8
11
C14
1µF
R12
47Ω
C4 TO C6
100µF
6.3V
3.3V @ 3.3A
Q3
Si4490DY
R
CLASS
1%
NC
R
CLASS
NC
V
IN
C1B
0.82µF
100V
C1C
0.82µF
100V
L1
4.7µH
Q2
MMBT3904
Q4
MMBT2907ALT1
Q5
MMBT3904
R9
100Ω
R8
47Ω
R6
47Ω
C9
100pF
D2
BAT54
Q1
MMBTA06
D4
BAS21LT1
D1
12V
D3A D3B
R7
33Ω
1/4W
C1A
10µF
100V
R5
47K
+
Q9
2N7002
D13
MMSD4148
C11
0.1µF
100V
D6
SMAJ58A
R30
75Ω
C24
0.01µF
200V
R31
75Ω
C25
0.01µF
200V
R1
75Ω
C7
0.01µF
200V
R2
75Ω
C3
0.01µF
200V
C2
1000pF
2kV
42571 TA02
D10
B1100
D12
B1100
D9
B1100
D11
B1100
D17
B1100
D16
B1100
D15
B1100
D14
B1100
3
4
4
LTC4257CDD-1
GND
SIGDISA
PWRGD
V
OUT
Figure 11. PD Power Interface with 3.3V, 3.3A High Efficiency Isolated Power Supply