LTC4257IS8 Linear Technology, LTC4257IS8 Datasheet - Page 20

• 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

TYPICAL APPLICATIO
RELATED PARTS
LTC4257
RJ45
PART NUMBER
LTC1737
LTC1871
LTC3803
LTC4257-1
LTC4258
LTC4259A-1
LTC4267
Burst Mode is a registered trademark of Linear Technology Corporation. No R
20
J1
1
2
3
6
4
5
7
8
TX
TX
RX
RX
+
–
+
–
SPARE
SPARE
16
15
14
11
10
9
XFMR
T1
+
–
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
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone]
1
2
3
6
7
8
REFER TO DATA SHEET APPLICATIONS INFORMATION SECTION
TXOUT
TXOUT
RXOUT
RXOUT
75Ω
CLASS
0.01µF
+
200V
–
+
–
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
IEEE 802.3af PD Interface Controller with
Integrated Switching Regulator
TO
PHY
FOR CLASS 1-4 OPERATION.
75Ω
R11
75Ω
R12
75Ω
●
0.01µF
C4
0.01µF
200V
C3
0.01µF
200V
200V
FAX: [phone]
3
C8
0.001µF
2kV
PD Power Interface with 3.3V, 3A Nonisolated Power Supply
~
~
~
~
DF01SA
DF01SA
U
BR1
BR2
SENSE
+
–
+
–
●
™ Current Mode Flyback,
www.linear.com
D3
TVS
SMAJ58A
0.1µF
100V
C14
SENSE
1N4148
R9
100k
R18
10k
D6
and ThinSOT are trademarks of Linear Technology Corporation.
R
1%
CLASS
100Ω
2
R16
FMMT2222
NC
R
NC
V
IN
CLASS
Q4
R17
750Ω
LTC4257
100k
R10
PWRGD
V
GND
1µF 6.3V
OUT
NC
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, Dual Current Limit
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
100V, 400mA Internal Switch, 16-Pin SSOP or 3mm × 5mm
DFN Packages
80.6k
C
1nF
C6
1%
R
C1
12k
R
T
C
+
C1A
4.7µF
100V
2.2µF
21k 1%
R14
12.4k
1%
1µH
100V
L1
C1B
R15
RUN
I
FB
FREQ
MODE/SYNC
TH
LTC1871
MMBZ5235B
INTV
SENSE
GATE
GND
6.8V
V
D4
CC
4.7µF
IN
6.3V
CTX-02-15242
C5
R13
100k
2
C™ Control
®
Q2
FMMT625
T2
© LINEAR TECHNOLOGY CORPORATION 2003
Operation at Light Load
2
4
•
Q3
FDC2512
11
R5
0.1Ω
1%
9
• •
10
12
UPS840
D5
LT 1205 REV B • PRINTED IN USA
2
C Control
+
100µF
6.3V
X5R
C9
100µF
X5R
6.3V
C10
+
+
100µF
6.3V
X5R
C13
C12
100µF
X5R
6.3V
+
4257 TA03
4257fb
V
3.3V
AT 3A
V
OUT
OUT
+
–