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参数资料
| 型号： | LTC4266CIUHF#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源管理 |
| 英文描述： | POWER SUPPLY MANAGEMENT CKT, PQCC38 |
| 封装： | 7 X 5 MM, LEAD FREE, PLASTIC, MO-220WHKD, QFN-38 |
| 文件页数： | 11/28页 |
| 文件大小： | 325K |
| 代理商： | LTC4266CIUHF#PBF |
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LTC4266A/LTC4266C
19
4266acf
ApplicAtions inForMAtion
BehaviorinAUTOpinmodeissimilartosemi-auto;however,
after Detect Good is reported and the port is classified (if
classification is enabled), it is automatically powered on
without further intervention. In standalone (AUTO pin)
mode, the ICUT and ILIM thresholds are automatically set;
see the Reset and the AUTO/MID Pin section for more
information.
The signature detection circuitry is disabled when the port
is initially powered up with the AUTO pin low, in shutdown
mode, or when the corresponding Detect Enable bit is
cleared.
Detection of Legacy PDs
Proprietary PDs that predate the original IEEE 802.3af
standard are commonly referred to today as legacy de-
vices. One type of legacy PD uses a large common mode
capacitance (>10μF) as the detection signature. Note that
PDs in this range of capacitance are defined as invalid, so
a PSE that detects legacy PDs is technically noncompliant
with the IEEE spec.
The LTC4266A/LTC4266C can be configured to detect
this type of legacy PD. Legacy detection is disabled by
default, but can be manually enabled on a per-port basis.
When enabled, the port will report Detect Good when it
sees either a valid IEEE PD or a high-capacitance legacy
PD. With legacy mode disabled, only valid IEEE PDs will
be recognized.
CLASSIFICATION
802.3af Classification
A PD can optionally present a classification signature to
the PSE to indicate the maximum power it will draw while
operating. The IEEE specification defines this signature as
a constant current draw when the PSE port voltage is in the
VCLASS range (between 15.5V and 20.5V), with the current
level indicating one of 5 possible PD classes. Figure 13
shows a typical PD load line, starting with the slope of the
25k signature resistor below 10V, then transitioning to
the classification signature current (in this case, Class 3)
in the VCLASS range. Table 4 shows the possible clas-
sification values.
Table 4. Classification Values
CLASS
RESULT
Class 0
No Class Signature Present; Treat Like Class 3
Class 1
3W
Class 2
7W
Class 3
13W
Class 4
25.5W (Type 2)
If classification is enabled, the port will classify the PD
immediatelyafterasuccessfuldetectioncycleinsemi-auto
or AUTO pin modes, or when commanded to in manual
mode. It measures the PD classification signature by ap-
plying 18V for 12ms (both values typical) to the port via
the OUTn pin and measuring the resulting current; it then
reports the discovered class in the Port Status register.
If the LTC4266A/LTC4266C is in AUTO pin mode, it will
additionally use the classification result to set the ICUT
and ILIM thresholds. See the Reset and the AUTO/MID Pin
section for more information.
The classification circuitry is disabled when the port is
initially powered up with the AUTO pin low, in shutdown
mode, or when the corresponding Class Enable bit is
cleared.
Figure 13. PD Classification
VOLTAGE (VCLASS)
0
CURRENT
(mA)
60
50
40
30
20
10
0
5
10
15
20
4266AC F13
25
TYPICAL
CLASS 3
PD LOAD
LINE
48mA
33mA
PSE LOAD LINE
23mA
14.5mA
6.5mA
CLASS 4
CLASS 2
CLASS 1
CLASS 0
CLASS 3
OVER
CURRENT
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC4266CUHF#PBF | 制造商:Linear Technology 功能描述:POE Controller 25.5W 38-Pin QFN EP 制造商:Linear Technology 功能描述:IC POE CONTROLLER 3.3V QFN-38 制造商:Linear Technology 功能描述:IC, POE CONTROLLER, 3.3V, QFN-38; Input Voltage:3.3V; Supply Current:-2.4mA; UVLO:25V; Digital IC Case Style:QFN; No. of Pins:38; Frequency:1MHz; Operating Temperature Min:0C; Operating Temperature Max:70C; MSL:MSL 1 - Unlimited ;RoHS Compliant: Yes |
| LTC4266CUHF#TRPBF | 制造商:Linear Technology 功能描述:POE Controller 25.5W 38-Pin QFN EP |
| LTC4266IGW#PBF | 功能描述:IC CTRLR IEEE 802.3AT 36-SSOP RoHS:是 类别:集成电路 (IC) >> 接口 - 控制器 系列:- 标准包装:2,450 系列:- 控制器类型:SPI 总线至 I²C 总线桥接 接口:I²C，串行，SPI 电源电压:2.4 V ~ 3.6 V 电流 - 电源:11mA 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:24-VFQFN 裸露焊盘 供应商设备封装:24-HVQFN（4x4） 包装:托盘 配用:568-3511-ND - DEMO BOARD SPI TO I2C 其它名称:935286452157SC18IS600IBSSC18IS600IBS-ND |
| LTC4266IGW#TRPBF | 制造商:Linear Technology 功能描述:Power Over Ethernet Controller 36-Pin SSOP W T/R 制造商:Linear Technology 功能描述:MS-Hot Swap/POE, PoE+ 25.5W Quad PSE Controller |
| LTC4266IUHF#PBF | 制造商:Linear Technology 功能描述:POE Controller 25.5W 38-Pin QFN EP 制造商:Linear Technology 功能描述:IC POE 802.3AT QUAD PSE 38-QFN 制造商:Linear Technology 功能描述:POE CNTRL QUAD 25.5W 1MHZ 制造商:Linear Technology 功能描述:IC, POE CONTROLLER, 3.3V, QFN-38; Input Voltage:3.3V; Supply Current:-2.4mA; UVLO:25V; Digital IC Case Style:QFN; No. of Pins:38; Frequency:1MHz; Operating Temperature Min:-40C; Operating Temperature Max:85C; MSL:MSL 1 - Unlimited ;RoHS Compliant: Yes |
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