LTC4257-1 Linear Technology, LTC4257-1 Datasheet - Page 20

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

TYPICAL APPLICATIO
RELATED PARTS
LTC4257-1
PART NUMBER
LTC1737
LTC1871
LTC3803
LTC4257
LTC4258
LTC4259
Burst Mode is a registered trademark of Linear Technology Corporation. No R
20
RJ45
J1
1
2
3
6
4
5
7
8
TX
TX
RX
RX
+
–
+
–
SPARE
SPARE
16
15
14
11
10
9
XFMR
T1
+
–
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] FAX: [phone]
1
2
3
6
7
8
NOTES: UNLESS OTHERWISE SPECIFIED
1. ALL RESISTOR VALUES ARE 5%
2. SELECT R
3. CONNECT TO CHASSIS GROUND
C1A: PANASONIC ECEV2AA4R7P
C1B: TDK C5750X7R2A225KT
C8: AVX 1808GC102MAT
C9, C10, C12, C13: TDK C4532X5ROJ107
L1: LQLB2518T1ROM
T1: PULSE H2019
REFER TO DATA SHEET APPLICATIONS INFORMATION SECTION
TXOUT
TXOUT
RXOUT
RXOUT
75
0.01 F
+
–
+
200V
–
CLASS
DESCRIPTION
High Power Isolated Flyback Controller
Wide Input Range, No R
Boost and SEPIC Controller
Current Mode Flyback DC/DC Controller in ThinSOT™
IEEE 802.3af PD Interface Controller
Quad IEEE 802.3af Power over Ethernet Controller
Quad IEEE 802.3af Power over Ethernet Controller
TO
PHY
FOR CLASS 1-4 OPERATION.
75
R12
75
R11
75
0.01 F
C4
0.01 F
200V
C3
0.01 F
200V
200V
3
C8
0.001 F
2kV
4
3
4
3
PD Power Interface with 3.3V, 3A Nonisolated Power Supply
~
DF01SA
~
~
DF01SA
~
U
BR1
BR2
SENSE
+
–
+
–
1
2
1
2
™ Current Mode Flyback,
www.linear.com
D3
TVS
SMAJ58A
0.1 F
100V
C14
SENSE
1N4148
R9
100k
R18
10k
D6
and ThinSOT are trademarks of Linear Technology Corporation. I
R
1%
CLASS
100
2
R16
FMMT2222
1
2
3
4
NC
R
NC
V
CLASS
IN
Q4
R17
750
LTC4257-1
100k
U1
R10
SIGDISA
PWRGD
V
GND
1 F 6.3V
OUT
Q1
2N7002
COMMENTS
Sense Output Voltage Directly from Primary-Side Winding
Adjustable Switching Frequency, Programmable Undervoltage
Lockout, Optional Burst Mode
200kHz Constant Frequency, Adjustable Slope Compensation,
Optimized for High Input Voltage Applications
100V 400mA Internal Switch, Programmable Classification
DC Disconnect Only, IEEE-Compliant PD Detection and Classification,
Autonomous Operation or I
AC or DC Disconnect, IEEE-Compliant PD Detection and
Classification, Autonomous Operation or I
80.6k
C
1nF
C6
1%
R
C1
12k
R
T
8
7
6
5
C
+
C1A
4.7 F
100V
2.2 F
21k 1%
R14
12.4k
1%
1 H
100V
1
2
3
4
5
L1
C1B
R15
RUN
I
FB
FREQ
MODE/SYNC
TH
LTC1871
MMBZ5235B
U2
INTV
SENSE
GATE
GND
6.8V
V
D4
CC
4.7 F
IN
6.3V
CTX-02-15242
C5
10
9
8
7
6
R13
100k
2
C™ Control
®
2
Q2
FMMT625
T2
C is a trademark of Philips Electronics N.V.
2
4
Operation at Light Load
•
LINEAR TECHNOLOGY CORPORATION 2003
Q3
FDC2512
11
R5
0.1
1%
9
LT/TP 0204 1K REV A • PRINTED IN USA
• •
10
12
UPS840
D5
2
C Control
+
100 F
6.3V
X5R
C9
100 F
X5R
6.3V
C10
+
+
100 F
6.3V
X5R
C12
100 F
X5R
6.3V
C13
4257 TA03
+
42571fa
V
3.3V
AT 3A
V
OUT
OUT
+
–