Questions tagged [poe]

Power over Ethernet, a set of IEEE standards for transmitting electrical power along with data through an Ethernet cable.

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Is it safe to connect an oscilloscope to a Power over Ethernet line?

I have found that PoE uses isolated power delivery. If I splice into my ethernet cable, will I be able to hook up a scope to one of the 8 lines inside safely without frying anything? The scope and the ...
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Microcontroller kit with PoE capability [closed]

With previous projects involving different boxes (essentially different input & output quantities), we just re-used this kit: https://www.ti.com/tool/EK-TM4C1294XL If a certain box needs more I/O ...
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High power & ethernet over SF/FTP using the cable's shield

I'm working on a custom gigabit high-power POE solution (ideally 200+ watts). Since SF/FTP cable has a lot of shielding, why not use it as a conductor? Using all 4 twisted pairs for DC+ and the shield ...
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Circuit appeared to work for a few minutes at first, then poof! Can you help me figure it out? Diagram included

thank you for taking the time. I have this PoE design that takes 48V and knocks it down to 5V for powering generic USB devices. I received some new boards and when testing them, discovered they ...
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Can I directly connect four lead acid batteries for UPS (MeanWell ADD-155C)? Which voltage should I set?

I want to power my Mikrotik HEX POE switch which accepts up to 57V DC through a DIY UPS. I want to build it from a MeanWell ADD-155C which haa battery connector (<...
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Understanding 24 V PoE mode B magjack connections

Having just realised I have screwed up my board by stupidly swapping pins 4 & 5 on the magjack output, I have realised I don't properly understand the PoE power pins on the magjack. I wonder if ...
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What are the recommended differential trace characteristics for Power over Ethernet input section?

I've been looking through a few application notes for Power over Ethernet front ends such as Microchip AN3468 and Skyworks AN1130. I can't figure out what the characteristic impedance of the ...
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Compatible High-Power PoE Ethernet Magnetics and PHY

I'm building a high-power (~70-90W) PoE system, anticipating 4-pair power (Type 4 PoE) and am working to select a combination of high-power capable magnetics that is compatible with a basic 10/100 PHY....
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Best way to connect Raspberry Pi Pico to apartment monitor?

I'm trying to power my Raspberry Pi Pico using the existing power connection for my apartment monitor (link to manual) I note on the back of the monitor, there are unused pins, specifically a 12v and ...
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Is there a standard PoE+ input symbol for a product label?

I was expecting to easily find this. However, unlike other safety symbols (such as double insulation / Class 2) I cannot seem to find a lead. Was convinced this would fall under some sort of safety as ...
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What voltage regulator is used for PoE Splitter and Switches?

What is the working principle / hardware that is used for common PoE switches or PoE splitters. Please see following hardware examples: TP-Link PoE Switch RPI PoE Splitter I am asking this question ...
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Protect RJ45 CAN from POE

I'm trying to design a PCB with CAN Bus connection with STM32 (will be using a CAN transceiver) where we're using RJ45 for the CAN port. One of the main concern is what if the user plug in a Power ...
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Efficient Multi-Voltage Output in PoE Circuit via Custom Transformer

I'm working to maximize the efficiency of the isolation circuit on a PoE device in order to maximize power delivery to the device itself. Since the PoE spec requires isolation, I was wondering if it ...
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What's the cheapest way to design this circuit?

I design a board with Power over Ethernet (PoE 802.3af/at) and the standard requires a "Maintain Power Signature" (MPS) signal, which is a 10 mA, 75 ms pulse every 325 ms (roughly 25 % D.C.)....
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Limiting peak current draw with a supercapacitor or battery

I'm working on a project that runs on 12V DC. The power comes via PoE, which induces a hard limit of 15 watts on the design. The circuit is intended to drive multiple loads that are rated for ~7W each,...
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How to implement POE on PIC18

I am trying to create a PCB containing a PIC18F66J60. I want to power the board using POE. For the POE i plan to use the TPS2375PW. The two IC's have two quite different refferent schematics in their ...
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PoE system with Active Clamp Forward

Does anyone know if choose the Active clamp forward as the topology in PoE system, according to this figure which from TI Design document, What's the function of C39. I do not understand why need to ...
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What is ORing and why is it named ORing?

I read some documents like the PoE application, it used ORing to protect the reverse input current. I would like to know what ORing is. I googled it, but I cannot find the answer. It seems like a ...
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Type 3 PoE PD with High Efficiency DC-DC Controller

I am reading the TI POE IC(TPS23730's datasheet), and I have some questions I would like to ask you, if you can help me I will very much appreciate it. 1.) What's the internal hot-swap MOSFET, I have ...
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PoE woes with custom PSE board powering a Pi4B, is it termination?

Sorry if this is a bit long and rambling but I've been wrestling with this problem for far too long. I've designed and built a PCB that uses an STM32F767 processor and a LAN8742A as the Phy to ...
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Is it possible (with reasonable effort) to use ethernet hardware to provide point-to-point digital I/O bridge?

I'm interested in designing a "simple" circuit that would bridge digital inputs or outputs over a distance with relatively low latency. The idea is to take several pins from a GPIO bus like ...
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Passive POE 24V, how can it damage a non POE device

I read that active POE is safe, and that when performing the handshaking it can increase the voltage up to 10.1V. So I infer that generally Ethernet devices can handle 10V no problem. But what about ...
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POE daisychain design question

I would like to design a slave device that can communicate with POE in a daisychain configuration. I am going to use dual RJ45 port but in terms of connection of the transformer circuitry, I have no ...
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Drawing power from PoE without Ethernet

I was searching, but was not able to find an answer which is helping me. This is the first time I'm confronted with implementing something like this, so please excuse if this is a dumb question... My ...
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protect RS485 from PoE

I have a board with two RJ45 connectors. One is used for an Ethernet port and the other one is for a RS485. The Ethernet is for Power over Ethernet. What are some suggestions to protect the RS485 port ...
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Ethernet UTP cable test device, protection for PoE and signal voltages

I’m thinking about designing a device/tool for UTP cable related testing/tracing using an MCU. I just would like to experiment with some ideas involving wire measurements, tone measurements etc. (so ...
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Difference between the two Ethernet magnetic topologies

Background Hello, I'm building up a PCB for a PoE module based on Microchip LAN8720 IC. The recommended schematic is shown in the following figure. I built up a prototype based on the Waveshare ...
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AG9205S PoE PD Module and Raspberry PI

I have in my hand a AG9205s PoE PD module (output 5V and up to 13W) and I want to use it with my Raspberry PI 3B+ (that exposes the center core tap wires to the J14 pin header, as you can check here ...
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Can a PoE type Gigabit Ethernet Transformer be used in a non PoE application?

I am designing a device that will have Gigabit Ethernet ports on it. We have a requirement that our device must be stored at -50C. Many gigabit ethernet transformers either don't list a min storage ...
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Why does PoE use 4 wires to deliver power?

I know Ethernet uses differential signaling that's why you need 2 wires for transmit and another 2 wires for receive. But what about power? Why are 4 wires used?
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how to make an obfuscated network cable

(EDIT): forest for the trees This is why I love StackExchange! I have several great ideas to try, none of which were my original. I asked here based on an assumption I probably shouldn't make: my ...
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How does Power over Ethernet classification work?

In this TPS2372 PoE PD there is a table about how to set up classification of the device. I think I understand the concept of classifying PD devices, it's to tell the supply equipment the power demand ...
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240 VAC power over ethernet?

Newbie to electricity here, quick question: I want to run electric over existing LAN cable (not POE), which of the following is better or workable: Scenario: 5 CCTV cameras, each requires 9V DC 0.6A ...
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2 votes
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How to properly read current of a PoE Mode A device?

I'm trying to measure the power consumption of a PoE device using Mode A. I assume I would need 2x current readings -- one for pin 1 (I1), one for pin 2 (I2), and then 1 voltage reading of from either ...
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What would happen if I send 220V to my ethernet port? [closed]

I found unused cables at home and I connected them: This is obviously made as a joke, but I keep wondering what would happen if I were to actually plug both ends in my computer. Is there some safety ...
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Limiting peak power consumption with energy bank

I have a POE splitter capable of delivering a maximum of 1A at 12V. This device is intended to power a Raspberry PI 3B+ and a 3.5 inch hard drive. The Pi gets the 5V from a DC to DC step down ...
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Switching Between PoE and Power Input of DC 8-36V

I am Planning to use PoE+ PD in my design. I have a DC power input option other than PoE which will be in range of 8-36V DC. I am planning to use one PD module with Integrated DC-DC converter which ...
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Power over Ethernet circuit connection

I'm thinking of making a simple PCB with RJ45 connector delivering both data to the control MCU and power to the whole PCB using the PoE technology. I'd like to use a LM5071 as a power source and i.e. ...
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Waterproofing a cat5e/6 repair

I have a 1200 foot long outdoor direct burial network cable running through an outdoor environment that ranges from dry to 6+ ft underwater depending on the year and season. (Currently it is a foot or ...
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ESD Protection for 1Gb Ethernet pre-magnetics able to withstand PoE?

I am looking for suggestions on protecting a gigabit ethernet port from ESD between the jack and the magnetics. Due to the nature of the equipment design, the magnetics cannot be placed next to the ...
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How to use PoE to power an additional device?

I have an Ethernet (100 Mbps) camera powered through PoE by a PoE enabled switch. The camera is turned on and shut down by configuring the switch to cut the power on and off on the given port. I want ...
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How many watts to power up my POE camera?

I have a couple of IP cameras at my home. Brand/Model is EMINENT 6355. They work well with the provided injector. However, to avoid having a lot of injectors, I bought a switch LINKSYS LGS108P-EU (...
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When is it allowed to use non-isolated PoE?

Currently I am designing a circuit that is required to be PoE powered. We are debating whether to use an isolated or a non-isolated supply. The device is wall mounted and in a plastic enclosure. No ...
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Why does my NVR reset when its UPS switches to battery?

I have a Reolink network video recorder (NVR) that provides 802.3af Power over Ethernet to downstream cameras. This NVR is plugged into a uninterruptible power supply (UPS). I have a switch, whose ...
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PoE galvanic isolation necessary?

I am currently designing a battery powered LED project, that will be charged and/or operated over 25W PoE+. In my current design, I am using a flyback converter to convert the 48V to 12V and for ...
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POE Extraction and port reuse for POE Device

i need to get out from PoE cable 1A of power in order to drive some LCD Displays and leds, i've digged around and i've found some interesting POE extractor that can fit my requirements (like the ...
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Ethernet cable with largest conductor diameter

For a Power-over-Ethernet type of project, I'd like to use cables with low resistance. It seems a higher category (CAT5, CAT6, CAT7) does not necessarily mean the conductors used are larger in ...
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4 votes
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Does power delivery over ethernet always have to use isolated DC/DC converters?

I am examining the possibilities for building a cheap ethernet device that would be powered over ethernet using PoE technology. I came across this article which shows the generic block diagrams: ...
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POE power pass through

Is it possible to connect the center taps of two Ethernet magnetics to each other back-to-back to pass the power from one port to another. Does it make sense? Is anything special required?
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Can I use pre-regulated PoE power safely/within specifications?

I'm attempting to design a PoE PD for fairly high-power applications; chiefly, powering/driving stepper motors. Currently, both motors and drivers run at 24V and will consume about 30W per PD. At that ...
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