Linear Technology LTC4257CS8-1, Power-Over-Ethernet Interface Controller, Vsig = 48V, Vout = 3.3V DC671A DC671A Data Sheet

LTC4257-1

20

42571fb

Linear Technology  Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 

●

 FAX: (408) 434-0507 

 ● 

 www.linear.com

© LINEAR TECHNOLOGY CORPORATION 2003

LT 1205 1K REV B • PRINTED IN USA

1

3

2

RX

–

6

RX

+

3

TX

–

2

TX

+

J1

T1

XFMR

RJ45

1

7

8

5

4

SPARE

–

SPARE

+

6

8

7

TXOUT

+

TXOUT

–

RXOUT

+

RXOUT

–

TO
PHY

R12
75

Ω

R11
75

Ω

75

Ω

C4
0.01

µF

200V

C3
0.01

µF

200V

0.01

µF

200V

0.01

µF

200V

C8
0.001

µF

2kV

16

14

15

11

9

10

C14

0.1

µF

100V

LTC4257-1

LTC1871

Q3
FDC2512

C1A
4.7

µF

100V

Q2
FMMT625

D3
TVS
SMAJ58A

D4

MMBZ5235B

6.8V

R

CLASS

1%

NC

R

CLASS

NC

V

IN

GND

SIGDISA

PWRGD

V

OUT

RUN

I

TH

FB

FREQ

MODE/SYNC

SENSE

V

IN

INTV

CC

GATE

GND

BR2

DF01SA

~

+

~

–

BR1

DF01SA

~

+

~

–

C1B

2.2

µF

100V

R10

100k

R

T

80.6k

1%

R14
12.4k
1%

R15

21k 1%

C6

1

µF 6.3V

Q1
2N7002

C

C1

1nF

R

C

12k

R17
750

Ω

R13
100k

L1

1

µH

R16

100

Ω

Q4

FMMT2222

D6

1N4148

R9
100k

R18

10k

+

NOTES: UNLESS OTHERWISE SPECIFIED
1. ALL RESISTOR VALUES ARE 5%
2. SELECT R

CLASS

 FOR CLASS 1-4 OPERATION.

    REFER TO DATA SHEET APPLICATIONS INFORMATION SECTION
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

R5
0.1

Ω

1%

C5

4.7

µF

6.3V

•

4

2

11

9

T2

CTX-02-15242

D5

UPS840

12

4257 TA03

10

•

•

C9
100

µF

X5R
6.3V

C10

100

µF

X5R

6.3V

V

OUT

+

3.3V
AT 3A

V

OUT

–

+

+

C12
100

µF

X5R
6.3V

C13

100

µF

X5R

6.3V

+

+

3

2

75

Ω

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LTC1871

Wide Input Range, No R

SENSE

™ Current Mode Flyback,

Adjustable Switching Frequency, Programmable Undervoltage

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Lockout, Optional Burst Mode

®

 Operation at Light Load

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200kHz Constant Frequency, Adjustable Slope Compensation,
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100V, 400mA Internal Switch, Programmable Classification

LTC4258

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DC Disconnect Only, IEEE-Compliant PD Detection and Classification,
Autonomous Operation or I

2

C™ Control

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AC or DC Disconnect, IEEE-Compliant PD Detection and
Classification, Autonomous Operation or I

2

C Control

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Onboard 100V, 400mA Internal Switch, 16-Pin SSOP or 3mm 

× 5mm

Integrated Switching Regulator

DFN Packages

Burst Mode is a registered trademark of Linear Technology Corporation. No R

SENSE

 and ThinSOT are trademarks of Linear Technology Corporation.