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参数资料
| 型号： | LTC4267CGN-1#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | Power over Ethernet IEEE 802.3af PD Interface with Integrated Switching Regulator; Package: SSOP; No of Pins: 16; Temperature Range: 0°C to +70°C |
| 中文描述： | 1 A SWITCHING CONTROLLER, 240 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封装： | 0.150 INCH, LEAD FREE, PLASTIC, SSOP-16 |
| 文件页数： | 3/32页 |
| 文件大小： | 925K |
| 代理商： | LTC4267CGN-1#PBF |
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LTC4267-1
11
42671f
Series Diodes
The IEEE 802.3af-dened operating modes for a PD refer-
ence the input voltage at the RJ45 connector on the PD.
The PD must be able to accept power of either polarity
at each of its inputs, so it is common to install diode
bridges (Figure 2). The LTC4267-1 takes this into account
by compensating for these diode drops in the threshold
points for each range of operation. A similar adjustment
is made for the UVLO voltages.
Detection
During detection, the PSE will apply a voltage in the
range of –2.8V to –10V on the cable and look for a 25k
signature resistor. This identies the device at the end of
the cable as a PD. With the terminal voltage in this range,
the LTC4267-1 connects an internal 25k resistor between
the VPORTP and VPORTN pins. This precision, temperature
compensated resistor presents the proper signature to
alert the PSE that a PD is present and desires power to be
applied. The internal low-leakage UVLO switch prevents
the switching regulator circuitry from affecting the detec-
tion signature.
The LTC4267-1 is designed to compensate for the voltage
and resistance effects of the IEEE required diode bridge.
The signature range extends below the IEEE range to ac-
commodate the voltage drop of the two diodes. The IEEE
specication requires the PSE to use a
ΔV/ΔImeasurement
technique to keep the DC offset of these diodes from af-
fecting the signature resistance measurement. However,
the diode resistance appears in series with the signature
resistor and must be included in the overall signature
resistance of the PD. The LTC4267-1 compensates for
the two series diodes in the signature path by offsetting
the resistance so that a PD built using the LTC4267-1 will
meet the IEEE specication.
In some applications it is necessary to control whether
or not the PD is detected. In this case, the 25k signature
resistor can be enabled and disabled with the use of the
SIGDISA pin (Figure 3). Disabling the signature via the
SIGDISA pin will change the signature resistor to 9k
(typical) which is an invalid signature per the IEEE 802.3af
specication. This invalid signature is present for PD input
voltages from –2.8V to –10V. If the input rises above –10V,
the signature resistor reverts to 25k to minimize power
dissipation in the LTC4267-1. To disable the signature,
tie SIGDISA to VPORTP. Alternately, the SIGDISA pin can
be driven high with respect to VPORTN. When SIGDISA is
high, all functions of the PD interface are disabled.
APPLICATIO S I FOR ATIO
WU
UU
Figure 2. LTC4267-1 PD Front End Using
Diode Bridges on Main and Spare Inputs
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PDF描述 |
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| LTC4267CGN-1#TRPBF | Power over Ethernet IEEE 802.3af PD Interface with Integrated Switching Regulator; Package: SSOP; No of Pins: 16; Temperature Range: 0°C to +70°C |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC4267CGN-1-TR | 制造商:LINER 制造商全称:Linear Technology 功能描述:Power over Ethernet IEEE 802.3af PD Interface with Integrated Switching Regulator |
| LTC4267CGN-1-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Power over Ethernet IEEE 802.3af PD Interface with Integrated Switching Regulator |
| LTC4267CGN-3#PBF | 功能描述:IC POE 802.3AF W/REG 16-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 |
| LTC4267CGN-3#TRPBF | 功能描述:IC POE 802.3AF INTERFACE 16SSOP 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 |
| LTC4267CGNPBF | 制造商:Linear Technology 功能描述:Hot Swap Controller 1-Ch -57V SSOP16 |
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