以太网上的功率传输Linear

简介：

问：浪涌保护有什么具体措施？
答： How do you deal with the inrush? Please explain in detail.

On the Power Sourcing Equipment (PSE) side, our LTC4258/LTC4259 goes into current limit if 450mA is exceeded.  On the Powered Device (PD), IEEE requires that a PD should have at

问：以太网上用现有电缆提供电源最需要注意的地方在哪？它的应用前景如何？假如想用该技术单独做一产品可以是什么？
答： What is the concern in designing the POE system?How about the development future? What products can be made if we apply such technology?

Compatibility with multiple vendors is a concern.  That is why we offer reports from the UNH interop

问：能否对受电设备有软起动功能以减小浪涌电流?
答： Can we do soft-start for the PD so as to limit the inrush current?

Yes. The IEEE spec mandates a 450mA current limit at start up, and specifies a maximum voltage slew rate. Additional softstart is not required.

问：以太网的供电和固话网的远程供电原理是否相同？
答： Is the operation of POE the same as the power for telephone line?

No. Telephone power is applied differentially to the twisted pair wire. PoE is applied as a common mode signal between two twisted pairs.

问：以太网的RJ45端口中本来就定义了两根电源线完全可以用来传输功率,现讨论的传输功率有何不同,传输的功率容限和距离有何限制?如何抗干扰?个人认为只对微小功耗设备有意义!
答： The original definition of RJ45 use 2 wires to transmit power. What is the different power transmission on this discussion. What is the transmission power limit as well as distance limit? How to take care of noise immunity? My personal feeling is that it i

问：标准网线可以承受的功率是多少？
答： What is the max. power can the standard power line afford?

A PD can draw up to 12.95W.

问：如何减少供电线路中的高频成分？
答： How to reduce the high frequency content over such power delivering system?

The output of a Power Sourcing Equipment (PSE) allows for up to 520nF of a capacitance during detection.  The input of a PD must have between 0.05uF to 0.12uF of

问：此次讨论的以太网是在何种带宽下讨论？
答： What bandwidth (speed) of Ethernet are you talking about in the POE seminar?

10/100 and Gigabit are all supported.

问：新的标准下，以太网的传输距离能达到多少？如果扩展距离有何办法？
答： Power is tranmitted over the Signal Pairs or over the Spare Pairs.  The spare pairs are unused pairs and 48 volts can be directly applied across them.  If power is transmitted over the signal pairs, it must be applied through the common

问：实际以太网的功率传输和额定值有多大偏差？

答： How much is the max. power and tolerance?

The PD is allowed to draw up to 12.95W. Voltage range is 36V min to 57V max.

The PSE must supply at least 15.4W to the port. Voltage range is 44V min to 57V max. The extra power at the PSE is to a