參數(shù)資料
型號(hào): LTC4257IDD#TRPBF
廠商: Linear Technology
文件頁數(shù): 1/20頁
文件大?。?/td> 263K
描述: IC CONTROLLER POE INTERFACE 8DFN
標(biāo)準(zhǔn)包裝: 2,500
類型: 以太網(wǎng)供電開關(guān)(PoE)
應(yīng)用: IP 電話,LAN 網(wǎng)絡(luò)供電,網(wǎng)絡(luò)路由器和交換機(jī)
內(nèi)部開關(guān):
電流限制: 350mA
工作溫度: -40°C ~ 85°C
安裝類型: 表面貼裝
封裝/外殼: 8-WFDFN 裸露焊盤
供應(yīng)商設(shè)備封裝: 8-DFN-EP(3x3)
包裝: 帶卷 (TR)
LTC4257
1
4257fb
The LTC
?/DIV>
4257 provides complete signature and power
interface functions for a device operating in an IEEE
802.3af Power over Ethernet (PoE) system. The LTC4257
simplifies Powered Device (PD) design by incorporating
the 25k signature resistor, the classification current source,
input current limit with thermal foldback, undervoltage
lockout and power good signalling, all in a single 8-pin
package. By incorporating a high voltage power MOSFET
onboard, the LTC4257 provides the system designer with
reduced cost while also saving board space.
The LTC4257 can interface directly with a variety of Linear
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
solutions for Power Sourcing Equipment (PSE) applica-
tions with quad network power controllers.
The LTC4257 is available in the 8-pin SO and low profile
(3mm ?3mm) DFN packages.
?/DIV>
IP Phone Power Management
?/DIV>
Wireless Access Points
?/DIV>
Telecom Power Control
, LTC and LT are registered trademarks of Linear Technology Corporation.
?/DIV>
Complete Power Interface Port for IEEE 802.3af
?/DIV>
Powered Devices (PDs)
?/DIV>
Onboard 100V, 400mA Power MOSFET
?/DIV>
Precision Input Current Limit
?/DIV>
Onboard 25k Signature Resistor
?/DIV>
Programmable Classification Current (Class 0-4)
?/DIV>
Undervoltage Lockout
?/DIV>
Smart Thermal Protection
?/DIV>
Power Good Signal
?/DIV>
Available in 8-Pin SO and Low Profile (3mm ?3mm)
DFN Packages
IEEE 802.3af PD
Power over Ethernet
Interface Controller
GND
R
CLASS
R
CLASS
SMAJ58A
0.1礔
PWRGD
LTC4257
V
IN
SHDN
5礔
MIN
100k
3.3V
TO LOGIC
RTN
SWITCHING
POWER SUPPLY
V
IN
V
OUT
48V FROM
POWER SOURCING
EQUIPMENT
(PSE)
4257 TA01
+

+
DF01SA
~
~
+

Powered Device (PD)
5ms/DIV
V
IN
50V/DIV
V
OUT
20V/DIV
I
IN
200mA/DIV
PWRGD
50V/DIV
4225 TA02
LTC4257 Charging 300?/SPAN>F
Load Capacitor
FEATURES
DESCRIPTIO
APPLICATIO S
TYPICAL APPLICATIO
All other trademarks are the property of their respective owners.
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