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LTC4257CDD-1

Description
Power over Ethernet Interface Controller with Dual Current Limit
CategoryPower/power management    The power supply circuit   
File Size266KB,20 Pages
ManufacturerLinear ( ADI )
Websitehttp://www.analog.com/cn/index.html
Download Datasheet Parametric Compare View All

LTC4257CDD-1 Overview

Power over Ethernet Interface Controller with Dual Current Limit

LTC4257CDD-1 Parametric

Parameter NameAttribute value
Brand NameLinear Technology
Is it Rohs certified?incompatible
MakerLinear ( ADI )
Parts packaging codeDFN
package instructionVSON, SOLCC8,.11,20
Contacts8
Manufacturer packaging codeDD
Reach Compliance Code_compli
ECCN codeEAR99
Other featuresREQUIRES A NEGATIVE SUPPLY OF 48V
Adjustable thresholdNO
Analog Integrated Circuits - Other TypesPOWER SUPPLY SUPPORT CIRCUIT
JESD-30 codeS-PDSO-N8
JESD-609 codee0
length3 mm
Humidity sensitivity level1
Number of channels1
Number of functions1
Number of terminals8
Maximum operating temperature70 °C
Minimum operating temperature
Package body materialPLASTIC/EPOXY
encapsulated codeVSON
Encapsulate equivalent codeSOLCC8,.11,20
Package shapeSQUARE
Package formSMALL OUTLINE, VERY THIN PROFILE
Peak Reflow Temperature (Celsius)235
Certification statusNot Qualified
Maximum seat height0.8 mm
Maximum supply current (Isup)3 mA
surface mountYES
technologyCMOS
Temperature levelCOMMERCIAL
Terminal surfaceTin/Lead (Sn/Pb)
Terminal formNO LEAD
Terminal pitch0.5 mm
Terminal locationDUAL
Maximum time at peak reflow temperature20
width3 mm
LTC4257-1
IEEE 802.3af PD
Power over Ethernet Interface
Controller with Dual Current Limit
FEATURES
s
s
s
s
s
s
s
s
s
DESCRIPTIO
Complete Power Interface Port for IEEE 802
®
.3af
Powered Devices (PDs)
Onboard 100V, 400mA Power MOSFET
Precision Dual Level Current Limit
Onboard 25k Signature Resistor with Disable
Programmable Classification Current (Class 0-4)
Undervoltage Lockout
Thermal Overload Protection
Power Good Signal
Available in 8-Pin SO and Low Profile (3mm
×
3mm)
DFN Packages
APPLICATIO S
s
s
s
IP Phone Power Management
Wireless Access Points
Telecom Power Control
The LTC
®
4257-1 provides complete signature and power
interface functions for a device operating in an IEEE
802.3af Power over Ethernet (PoE) system. The LTC4257-1
simplifies Powered Device (PD) design by incorporating
the 25k signature resistor, classification current source,
input current limit, undervoltage lockout, thermal over-
load protection, signature disable and power good signal-
ling, all in a single 8-pin package. The LTC4257-1 includes
a precision, dual level current limit circuit. This allows it to
charge large load capacitors and interface with legacy
Power over Ethernet systems while maintaining compat-
ibility with the current IEEE 802.3af specification. By
incorporating a high voltage power MOSFET onboard, the
LTC4257-1 provides the system designer with reduced
cost while also saving board space.
The LTC4257-1 can interface directly with a variety of Lin-
ear Technology DC/DC converter products to provide a cost
effective power solution for IP phones, wireless access
points and other PDs. Linear Technology also provides
network power controllers for Power Sourcing Equipment
(PSE) applications.
The LTC4257-1 is available in the 8-pin SO and low profile
(3mm
×
3mm) DFN packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
802 is a registered trademark of Institute of Electrical and Electronics Engineers, Inc.
TYPICAL APPLICATIO
Powered Device (PD)
~
–48V FROM
POWER SOURCING
EQUIPMENT
(PSE)
+
0.1µF
SMAJ58A
LTC4257-1
GND
R
CLASS
SIGDISA
5µF
MIN
100k
+
DF01SA
SWITCHING
POWER SUPPLY
SHDN
RTN
~
R
CLASS
V
IN
PWRGD
V
OUT
U
V
IN
U
U
+
3.3V
TO LOGIC
42571 TA01
42571fa
1

LTC4257CDD-1 Related Products

LTC4257CDD-1 LTC4257CS8-1 LTC4257IDD-1 LTC4257IS8-1
Description Power over Ethernet Interface Controller with Dual Current Limit Power over Ethernet Interface Controller with Dual Current Limit Power over Ethernet Interface Controller with Dual Current Limit Power over Ethernet Interface Controller with Dual Current Limit
Brand Name Linear Technology Linear Technology Linear Technology Linear Technology
Is it Rohs certified? incompatible incompatible incompatible incompatible
Maker Linear ( ADI ) Linear ( ADI ) Linear ( ADI ) Linear ( ADI )
Parts packaging code DFN SOIC DFN SOIC
package instruction VSON, SOLCC8,.11,20 SOP, SOP8,.25 VSON, SOLCC8,.11,20 SOP, SOP8,.25
Contacts 8 8 8 8
Manufacturer packaging code DD S8 DD S8
Reach Compliance Code _compli _compli _compli _compli
ECCN code EAR99 EAR99 EAR99 EAR99
Other features REQUIRES A NEGATIVE SUPPLY OF 48V REQUIRES A NEGATIVE SUPPLY OF 48V REQUIRES A NEGATIVE SUPPLY OF 48V REQUIRES A NEGATIVE SUPPLY OF 48V
Adjustable threshold NO NO NO NO
Analog Integrated Circuits - Other Types POWER SUPPLY SUPPORT CIRCUIT POWER SUPPLY SUPPORT CIRCUIT POWER SUPPLY SUPPORT CIRCUIT POWER SUPPLY SUPPORT CIRCUIT
JESD-30 code S-PDSO-N8 R-PDSO-G8 S-PDSO-N8 R-PDSO-G8
JESD-609 code e0 e0 e0 e0
length 3 mm 4.9025 mm 3 mm 4.9025 mm
Humidity sensitivity level 1 1 1 1
Number of channels 1 1 1 1
Number of functions 1 1 1 1
Number of terminals 8 8 8 8
Maximum operating temperature 70 °C 70 °C 85 °C 85 °C
Package body material PLASTIC/EPOXY PLASTIC/EPOXY PLASTIC/EPOXY PLASTIC/EPOXY
encapsulated code VSON SOP VSON SOP
Encapsulate equivalent code SOLCC8,.11,20 SOP8,.25 SOLCC8,.11,20 SOP8,.25
Package shape SQUARE RECTANGULAR SQUARE RECTANGULAR
Package form SMALL OUTLINE, VERY THIN PROFILE SMALL OUTLINE SMALL OUTLINE, VERY THIN PROFILE SMALL OUTLINE
Peak Reflow Temperature (Celsius) 235 235 235 235
Certification status Not Qualified Not Qualified Not Qualified Not Qualified
Maximum seat height 0.8 mm 1.752 mm 0.8 mm 1.752 mm
Maximum supply current (Isup) 3 mA 3 mA 3 mA 3 mA
surface mount YES YES YES YES
technology CMOS CMOS CMOS CMOS
Temperature level COMMERCIAL COMMERCIAL INDUSTRIAL INDUSTRIAL
Terminal surface Tin/Lead (Sn/Pb) Tin/Lead (Sn/Pb) Tin/Lead (Sn/Pb) Tin/Lead (Sn/Pb)
Terminal form NO LEAD GULL WING NO LEAD GULL WING
Terminal pitch 0.5 mm 1.27 mm 0.5 mm 1.27 mm
Terminal location DUAL DUAL DUAL DUAL
Maximum time at peak reflow temperature 20 20 20 20
width 3 mm 3.899 mm 3 mm 3.899 mm
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