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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Problem with PoE implementation and newer switches
I am using Power over Ethernet (MP8007 as Powered Device) and it works perfectly with old PoE switches and PoE injectors.
In this application PoE is used as a secondary power source so when the main ...
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PoE circuit can not connect when using injector
I am designing a PoE powered development board with an ESP32 microcontroller module.
I am using the following circuit for the PoE power supply:
This is a direct copy of the PoE power circuit used by ...
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Minimal PoE handshake to get 12W from an active PoE switch?
What are the minimum handshake elements required to get 12W out of a PoE switch (with 8P8C modular connector) in a compliant way? After some basic but time-consuming research, I found the following:
...
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What is 3 wire I2C?
This is first time I'm seeing 3 wire I2C and have no idea how it works. How can I implement it in STM32 in Cube IDE using its GUI?
I'm using TI TPS23881 (PSE controller) in one of my projects and I ...
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Useing a PoE RJ45 ICM Magnetics but not using it for PoE?
I plan on using the Bel G27-122T-015 (PoE ICM RJ45) but I don't need it for PoE. Can I just leave these pins unconnected? The ICM already has an internal Bob Smith termination.
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Feedback for ESP32-POE board
just working on an ESP32 board featuring a WROOM32-UE and POE functionality. One of my first PCBs, so I'd appreciate some overall feedback on layout and routing.
Note that not everything is done yet. ...
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Does PoE require impedance matching
I'm currently designing a PCB that's powered through Power-over Ethernet. It's my first time working with ethernet on a PCB. I've based the schematic on a Development board by Espressif (Link : https:/...
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Hot-plugging current - TVS and ethernet
My question is based on this question over here
In one of the comments, it is mentioned,
"TVS on the media side would seem to invite short-circuit currents on hot-plugging. Putting it behind the ...
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Ethernet questions - SPE
I have a question regarding Single Pair Ethernet, is it possible to carry power with two wires?
For example, controlling and powering a motor 12V 0.5/1A
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Not working IEEE 802.3af PoE-PD Interface Controller (NCP1091)
For a hobby project, I am developing a PoE-powered PCB. At the moment, I have the following schematic and pcb layout designed.
When testing the PCB, I just can't get the PoE to work. My Switch (...
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Testing Ethernet POE and surge\transients from other sources like lightning
I've got a POE Powered Device (PD) that I would like to make sure the surge protection is functioning in the event of a surge that it doesn't take down my device. How could I test for surge\transient ...
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Ethernet transformer RX Centre tap connection to ground
I was going through some schematics that would have a PoE application and stumbled upon the below portion of a PoE camera application schematic.
In the above schematic, we can see the R66 resistor is ...
user220456
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PoE supply : what isolation is garanteed?
I'm currently designing a PCB that will be powered by PoE (or external supply).
I have some doubts about what isolation the PoE supply (PSE, typically a PoE switch) is guaranteed to provide :
are the ...
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What are the rated voltage and current of a single wire within an ethernet cable?
I haven't been able to find a clear cut answer to this question. I've found online somewhere that the entire cable can carry a max of 57V. Each pair can carry a max of 960mA. Is there any validity to ...
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Convert On-Q Legrand intercom to powered doorbell
My home came with a c.2007 On-Q Legrand Inquire 1000 intercom system. All stations only issue a gravely hiss. The Talk and Door buttons do not work. Mute works. Volume adjust works.
All units use Cat ...
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Can I run a dedicated power source through along with Ethernet?
Instead of utilizing POE, what if I used a seperate power supply for power and Ethernet for data using 2-pair shielded Cat5. Has anybody ever tried this, or thought of it? Are there any theoretical ...
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Using resistors to create a virtual center tap in PoE applications
I am designing an application where existing PoE infrastructure should be used to power a device instead of supplying each device with its own power supply.
In this application, no data needs to be ...
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ANDing isolated power supplies
Is there any specific challenge to ANDing two isolated power supplies, assuming that ideal diodes are used on their outputs? I'm interested in making a particularly compact PoE supply capable of ...
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What's the connector on this PSU for a PoE switch?
I bought this switching power supply (PAC-500WA-BE) that I plan to use to power a PoE switch.
The documentation is very poor and I would like to know the name of the connector on the back, where the ...
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Power over Ethernet voltage
Is all PoE 48 V DC?
We are building a PoE power supply at 48 V DC. Do the 12 V loads decrease the 48 V to 12 V?
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Does a non-isolated PoE Splitter comply with IEEE 802.3 clause 33.4?
PoE Splitters that are freely available on the market for purchase by end users frequently are non-isolating, i.e. their power output is galvanically connected to the twisted pairs of the Ethernet ...
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How do you measure power consumed by a PoE-powered device?
For a weekend project I would like to make a Power Over Ethernet (PoE) power meter. There have been five situations where this could have come in handy during fault-finding in my projects. I finally ...
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Does an outdoor PoE Access Point need seperate grounding?
I've searched high and low for an definitive answer on this, including speaking with electricians, but still get conflicting opinions on this.
The goal:
Install an outdoor wifi access point (AP), ...
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What to connect to center-taps of Ethernet magnetics?
I'm designing a couple of PCBs to send data and be powered over Ethernet, however, I am not entirely sure what to connect to the center taps.
I've heard different suggestions, from connecting it to 3....
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Whole-house DC using PoE cheaper than multiple 5/12 V wall warts?
I have seen plenty of questions asked and answered about setting up whole-house low-voltage DC via something like PoE (passive over standard Cat5e cable, run through plasterboard walls).
With the cost ...
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EMI Filter compatible to both IEEE 802.3at and MIL-461F standards
I'm designing an EMI filter for a PoE DC-DC converter. It's a typical filter:
However, IEEE 802.3at standard requires input bypass capacitor (from VDD to VSS) of 0.05 μF to 0.12 μF only.
Per my ...
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ESP32 with onboard ethernet interface [closed]
I'd like to know which is the best and chapest way to add an ethernet port (possibly POE enabled) to an ESP32 board.
Alternatively I'm looking for a cheap ESP32 with onboard LAN.
Any idea?
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Ground reference for POE 48V
We have POE 802.3af in our design. We are facing some issues with it as elaborated below.
We have connected an LED load to the connector end with a POE splitter. A splitter is used to convert 48V to ...
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Multiple power banks to handle temporary increase in power demand
I have 1 PoE+ (Power over Ethernet) port from which I need to power 5 Raspberry Pi 4s.
The recommended power supply for Raspberry Pi 4 is 5.1 V / 3 A which gives 15.3 so 5 Pis will require up to 76.5 ...
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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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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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