Questions tagged [poe]

Power Over Ethernet.

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53 views

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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1answer
51 views

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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1answer
20 views

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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27 views

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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1answer
56 views

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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49 views

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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2answers
89 views

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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22 views

PoE Magjack wiring with PEM1300 PD Module

I'm designing a poe based board using PEM1300 PD module and using the si-52003-f rj45 connector. I'm unsure in how i have to cable the PoE PD module to the RJ45 Jack, i mean, i want (if possible) to ...
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148 views

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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1answer
49 views

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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3answers
4k views

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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1answer
51 views

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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33 views

Classification on PoE

I am working with a PoE device and it has a PD controller which allows for the user to set the power class requested by setting the class resistors (CLSA,CLSB). My question is if the PD class ...
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33 views

Multi-Voltage PoE Splitter

I researching a pet project for an electric door strike controlled by a networked microcontroller. I would like to use PoE to power all of the components (strike, microcontroller, RFID reader) using a ...
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2answers
39 views

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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1answer
167 views

Ethernet with transformer

I have a schematic of Ethernet Transformer that supports POE, and 2.5GBT. I plan on using Ethernet with transformer on my PCB to connect to Network Switch. Are pin VC12 13, VC36 14, VC45 15, VC78 16 ...
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1answer
75 views

UL certification requirements

I'm designing a circuit board for a large industrial product which is intended to be UL certified, so the boss wants as many individual submodules to be UL certified as possible, including mine. The ...
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12 views

4PPoE PD cost reduction

My current project is designing a PD circuit for use with 4PPoE/802.3bt (up to 60W), powering 24V stepper motors/drivers. I've found a couple of different chip combinations - I quite like this diode ...
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2answers
62 views

Single-package DC/DC converters for PoE — good idea?

I'm planning a design where we'll use PoE to power a data acquisition board (essentially, an ADC + microcontroller + ethernet PHY and interface). I look at DC/DC isolated converters to get the 5V or ...
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2answers
111 views

Two Gas Discharge Tube in parallel; a fast acting gas acting tube and a gas discharge tube

I want to know what happens if we put two gas discharge tube (fast acting GDT and a GDT in parallel), and a tvs diode in parallel. Would there be an issue in putting GDT in parallel? Datasheet of ...
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1answer
92 views

What are these resistors for?

I am looking at implementing a MOSFET Bridge Rectifier circuit. I am trying understand why there is a difference in the basic application circuit and layout from the app note. The layout image below ...
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1answer
33 views

FDMQ8203 vs. FDMQ8205/A

From the appnote FDMQ8205/A is almost identical to FDMQ8203 except the externa circuitry is no longer required. I am curious if anyone knows why in the FDMQ8205/A design VOUTN is NOT connected to ...
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38 views

How do you determine what amount of capacitance is bad for data lines?

I am currently deciding on putting a TVS diode from line to ground on POE ethernet. The issue is that I don't know how the capacitance of TVS diode will play role on the data signal. Is 1000pf bad or ...
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1answer
49 views

Ethernet POE voltage measurement to determine Voltage clamping between line ot Ground

I am planning on using a tvs diode to clamp power peak to protect network switch; the Port is POE. The issue is that when I measure the voltage of ethernet line to ground, I get around 0.6V. When I ...
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61 views

HR911105A or similar integrated magnetics for POE

Is it ok to use this RJ-45 socket for low power POE application (just to power the uC)? The only available datasheet : https://www.google.com/url?sa=t&source=web&rct=j&url=http://www....
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74 views

What to do with unused Ethernet magnetic center taps on POE?

I'm using a MAGJACK GIG PDJACK 1X1 CLASS 4 (Molex # 0857914020 - Link: https://www.digikey.com/products/en?keywords=WM9656-ND) to run POE on a 100MBit network connection. I thought this was a nice ...
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1answer
82 views

Practical considerations using Ethernet bus for a large number of sensors?

I understand that an Ethernet bus design with hubs has largely been superseded by star topologies with switches and that is largely due to the issues of collisions. However, I am interested in ...
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1answer
43 views

Measured Drain to Source Peak Voltage seems very high on PoE circuit

I am looking at TI's PMP20878 test results found on their website. Based on the schematic I am very confused how the Drain to Source peak voltage can be much greater than the typical PoE input of 48V. ...
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45 views

Are the topology of these flyback transformer for PoE the same?

I am looking for a transformer with the topology like 750310059 as shown below unfortunately the winding ratio and L value will not work with the PoE controller (MP8007) I am using for my design since ...
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1answer
79 views

PoE Design for Camera Interface Isolation Question

We are designing a PoE design to power our camera. The block diagram below is the basic design we are planning to implement. I want to get some advice to make sure we will not be damaging our camera ...
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1answer
41 views

What happens if PD tries to consume more than allowed PSE power provided? [closed]

What happens if a Powered Device (PD) tries to consume more than allowed (Power Sourcing Equipment) PSE power provided, even though it has requested a set amount of power? http://www.ti.com/lit/df/...
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1answer
95 views

POE design to support both Mode A and B

I am working on a POE design for the first time that supports 100Mbps. I plan on using the mEZS84801A evaluation board that uses MP8007 as a reference design to do all the signature detection, ...
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2answers
69 views

Two POE devices on One Ethernet Cable via a Y splitter

Is it possible to run two PoE devices at the same time off of 1 ethernet cable from a PSE? Assuming that the ethernet cable is run through some sort of custom splitter connector to both PoE Devices.
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33 views

PIC32MX795F512H + DP83822I Transmit Error Signal

I am using PIC32MX795F512H with DP83822I as the Ethernet PHY transceiver. On the PIC32MX there is a pin for Transmit Error (ETXERR) but no Transmit Error pin on DP83822I. What should I do with the ...
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2answers
508 views

What does Ethernet 100BASE-T signal look like?

Hey guys what does the signal look like on the right of the transformer (T1) on the data lines {TXD_P, RXD_P}? Just trying to understand what it might look like...Is it a square wave? sine wave? Vmax? ...
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1answer
44 views

PIC32MX795F512H Ethernet signals

Hey guys I am designing a PoE circuit board and the microcontroller that I want to use (PIC32MX795F512H) seems to be missing some pins to connect my data lines or it's not clear to me where the lines ...
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1answer
74 views

PoE Circuit Resistor Question

I was looking at a schematic provided by TI for a PoE power supply, and I had questions about certain resistors. What is the purpose of R5,R6,R7, and R8 in this schematic?
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2answers
83 views

Do PoE network switches have low output impedance and high input impedance?

I am just curious, and wanted to know if a Network Switches that have PoE ports have low output impedance, and high input impedance?
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116 views

PoE Transformer

I am using a transformer (7490220122) for signal isolation on a PoE controller design. If I am using 2 pair of the ethernet cable for data and 4 pair to provide the necessary power to the PoE device. ...
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2answers
491 views

isolated vs. non-isolated DC/DC converter in PoE

I am looking at powering a PoE circuit that drives a 24V motor at 2A. I am considering the LT4275/LT4276 LTPoE++™ Controller. I noticed on the datasheet for the controller LT4275 they recommend an "...
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70 views

PoE Design Question

I am working on a PoE project that calls for a power to be supplied to a application circuit. The application circuit requires ~41W (24V, 1.7A). I am exploring using PD70201 as the PD controller. The ...
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1answer
24 views

Why is the ground of the component, SP1050-04BTG, connected to the Power Supply of POE?

The SP1050-04BTG is a surge protector.
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2answers
116 views

PoE without DC/DC converter

I am planning on testing a PoE evaluation board (https://www.analog.com/media/en/dsp-documentation/evaluation-kit-manuals/dc2093af.pdf) with a pwm motor circuit. The PoE evaluation board doc ...
2
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1answer
70 views

GbE Phy(88E1543) with POE+ PSE(LTC4266) design (POE+ magnetics? RJ45 with Integrated magnetics?)

I'm trying to understand how i can inject power to a 4 bank RJ45. I want to use these parts : - LTC 4266 4 ports PSE (802.3 at compliant for GbE, in type1 class3 for 13W at each port) - Marvell ...
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3answers
273 views

DC-DC Buck Converter Failure Mystery

I'm a software engineer, so please excuse my gross ignorance of this topic. We are trying to figure out why our DC-DC converters sometimes fail and stop outputting power after a month or so of runtime....
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2answers
243 views

Can I run DC voltage through RJ45 Connector with Magnetics?

I am designing a PoE (Power over Ethernet) application. My question is can I run 48V DC Voltage through a standard RJ45 Jack WITH Magnetics? or do I need one WITHOUT magnetics? I am planning to use ...
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2answers
367 views

Develop PoE with Si3402

I am currently designing a PoE device with IC Si3402B Isolated refer and circuit my design: I use an RJ45 port with an internal diode bridge: I bought the RJ45 but not yet. I tested the external ...
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1answer
74 views

External Wall Adapter Detection in MP8007?

I am reading the datasheet of MP8007. I found ambiguity in section Wall Power Adaptor Detection and Operation on Page 16. After reading the section, i am not able ...
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1answer
288 views

Cable Side and Physical Side of a PoE Magnetics

I am reading the datasheet of PoE Magnetics. I am not able to understand which side belongs to cable side and which belongs to ...
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1answer
477 views

MagJack for PoE Powered Device

I am adding Power over Ethernet functionality in my Toradex's System-on-module (Colibri iMX6ULL) based carrier-board design. I ...