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參數(shù)資料
| 型號： | LTC4257CDD-1 |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 電源管理 |
| 英文描述： | Power over Ethernet Interface Controller with Dual Current Limit |
| 中文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO8 |
| 封裝： | 3 X 3 MM, PLASTIC, M0-229WEED-1, DFN-8 |
| 文件頁數(shù)： | 9/32頁 |
| 文件大?。?/td> | 1975K |
| 代理商： | LTC4257CDD-1 |
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LTC4267
9
4267f
4267 BD
V
PORTN
BOLD LINE INDICATES HIGH CURRENT PATH
P
OUT
–
+
PGND
R
CLASS
PWRGD
CONTROL
CIRCUITS
INPUT
CURRENT
LIMIT
POWER GOOD
CLASSIFICATION
CURRENT LOAD
1.237V
EN
375mA
140mA
9k
16k
–
+
EN
25k
SIGNATURE
RESISTOR
V
PORTP
SIGDISA
–
+
–
+
SLOPE
COMP
CURRENT
RAMP
P
VCC
GATE
DRIVER
NGATE
SENSE
200kHz
OSCILLATOR
UNDERVOLTAGE
LOCKOUT
Q
R
CURRENT
COMPARATOR
SHUTDOWN
COMPARATOR
SHUTDOWN
S
20mV
I
TH
/RUN
ERROR
AMPLIFIER
V
FB
SOFT-
START
CLAMP
V
SHUNT
REGULATOR
SWITCHING
LOGIC AND
BLANKING
CIRCUIT
0.28V
P
VCC
<
V
TURNON
0.3μA
P
VCC
–
+
1.2V
800mV
REFERENCE
OVERVIEW
The LTC4267 is partitioned into two major blocks: a
Powered Device (PD) interface controller and a current
mode flyback switching regulator. The Powered Device
(PD) interface is intended for use as the front end of a
PD adhering to the IEEE 802.3af standard, and includes
a trimmed 25k
Ω
signature resistor, classification current
source, and an input current limit circuit. With these
functions integrated into the LTC4267, the signature and
power interface for a PD can be built that meets all the
requirements of the IEEE 802.3af specification with a
minimum of external components.
The switching regulator portion of the LTC4267 is a con-
stant frequency current mode controller that is optimized
for Power over Ethernet applications. The regulator is
designed to drive a 6V N-channel MOSFET and features
soft-start and programmable slope compensation. The
integrated error amplifier and precision reference give the
PD designer the option of using a nonisolated topology
without the need for an external amplifier or reference. The
LTC4267 has been specifically designed to interface with
both IEEE compliant Power Sourcing Equipment (PSE)
and legacy PSEs which do not meet the inrush current
requirement of the IEEE 802.3af specification. By setting
the initial inrush current limit to a low level, a PD using
the LTC4267 minimizes the current drawn from the PSE
during start-up. After powering up, the LTC4267 switches
to the high level current limit, thereby allowing the PD to
consume up to 12.95W if an IEEE 802.3af PSE is present.
This low level current limit also allows the LTC4267 to
charge arbitrarily large load capacitors without exceeding
the inrush limits of the IEEE 802.3af specification. This
dual level current limit provides the system designer with
flexibility to design PDs which are compatible with legacy
PSEs while also being able to take advantage of the higher
power available in an IEEE 802.3af system.
Using an LTC4267 for the power and signature interface
functions of a PD provides several advantages. The
LTC4267 current limit circuit includes an onboard 100V,
400mA power MOSFET. This low leakage MOSFET is
APPLICATIU
W
U
U
BLOCK DIAGRA
W
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC4257CDD-1#PBF | 功能描述:IC CONTROLLER POE INTERFACE 8DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 標(biāo)準(zhǔn)包裝:50 系列:- 類型:熱交換控制器 應(yīng)用:-48V 遠程電力系統(tǒng)，AdvancedTCA ? 系統(tǒng)，高可用性 內(nèi)部開關(guān):無 電流限制:可調(diào) 電源電壓:11.5 V ~ 14.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬） 供應(yīng)商設(shè)備封裝:10-MSOP 包裝:管件 |
| LTC4257CDD-1#TR | 功能描述:IC CONTROLLER POE INTERFACE 8DFN RoHS:否 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 標(biāo)準(zhǔn)包裝:50 系列:- 類型:熱交換控制器 應(yīng)用:-48V 遠程電力系統(tǒng)，AdvancedTCA ? 系統(tǒng)，高可用性 內(nèi)部開關(guān):無 電流限制:可調(diào) 電源電壓:11.5 V ~ 14.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬） 供應(yīng)商設(shè)備封裝:10-MSOP 包裝:管件 |
| LTC4257CDD-1#TRPBF | 功能描述:IC CONTROLLER POE INTERFACE 8DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 標(biāo)準(zhǔn)包裝:50 系列:- 類型:熱交換控制器 應(yīng)用:-48V 遠程電力系統(tǒng)，AdvancedTCA ? 系統(tǒng)，高可用性 內(nèi)部開關(guān):無 電流限制:可調(diào) 電源電壓:11.5 V ~ 14.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬） 供應(yīng)商設(shè)備封裝:10-MSOP 包裝:管件 |
| LTC4257CS8 | 功能描述:IC CTRLR INTFACE PWR/ETHER 8SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 標(biāo)準(zhǔn)包裝:50 系列:- 類型:熱交換控制器 應(yīng)用:-48V 遠程電力系統(tǒng)，AdvancedTCA ? 系統(tǒng)，高可用性 內(nèi)部開關(guān):無 電流限制:可調(diào) 電源電壓:11.5 V ~ 14.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬） 供應(yīng)商設(shè)備封裝:10-MSOP 包裝:管件 |
| LTC4257CS8-#1TRPBF | 制造商:LINEAR_TECH 功能描述: |
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