Questions tagged [emc]
Electromagnetic compatibility (EMC) is a branch of electronics related to identifying and solving problems caused by electromagnetic interference (EMI) between devices. It encompasses both attempting to prevent unwanted emissions from a device and also ensuring that emissions from another device will not cause spurious operation. EMC depends upon many system-level details; when asking questions, please provide as much information as possible.
228
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How to mitigate excessive ringing in VDS and VGS
I have a few questions regarding my measurement results in the lab for a double pulse test setup. There are three issues which I want to mitigate
.
At turn-on interval, there is excessive ringing in ...
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Is there an antenna problem with CAN Bus selectable split termination header pin?
I am trying to implement a jumper-selectable CAN Bus termination with a SPLIT configuration, as shown in this Analog Devices example:
https://www.analog.com/media/en/technical-documentation/user-...
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Inverter EMI filter design
I'm designing an inverter with a switching frequency range of 10-40kHz. The inverter will run off of a DC power supply at a relatively low voltage (30-80VDC) and low power (~100W) for motor control ...
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FCC exemption for sub 1.705 MHz devices
The exemption section of the FCC rules on unintentional radiators (Title 47, chapter I, Subchapter A, Part 15, Subpart B, Section 15.103) has the following item :
(h) Digital devices in which both ...
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Multiple Crystal Oscillators Design Considerations
I am designing an acquisition system that has two parts, a hub and an acquisition part that collects the signals. The two parts communicate through FPGA Serdes.
The hub has a main clock from 16MHz ...
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188
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RFI protection for a stepper motor controller
I'm building a remote tuning device for a magnetic loop antenna. It will use a stepper motor to turn the shaft on the mag loop's variable capacitor. The electronics will consist primarily of a ...
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2
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How to perform conducted emission simulations
I am currently attempting to design an EMI filter for an AC/DC power supply that is too noisy to pass conducted EMI testing for MIL-STD-461 (115Vrms, 50Hz).
In the lab I have measured the DM and CM ...
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What is the purpose of connecting your reference ground plane to earth when doing radiated emissions testing?
In most standards it's required to connect the reference ground plane to earth.
However in a lot of cases the reference ground plane is elevated above the earth by a set height.
If you left the earth ...
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175
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Estimate susceptibility of circuits to external electrical field strength
I will be soon testing a product to an electric field spectrum requirement (i.e. in the 100's of dBµV/m vs MHz), and it shouldn't be a problem because of how small the values are compared to the ...
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Suggestion for ESD Chassis Ground for Battery-Operated Device with Plastic Enclosure
We are developing a wearable device that is battery powered which is enclosed with a plastic enclosure. As a requirement for safety, we submitted the device for EMC testing, which includes Indirect ...
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Trying to pass EMC Pre-Compliance Test without the use of electrolytic capacitor on DC/DC Converter
I’m designing a EMI filter for a DC/DC Converter Circuit and having trouble suppressing noise on 1.5-1.8MHz range. Usually an easy fix would be snap in a 100-220uF Electrolytic cap would do the trick ...
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EFT generator circuit
I am simulating a circuit to model the EN 61000-4-4 waveform for electrical fast transients using LTspice. The idea is to have the generator for some in house testing.
After a lot of back and fourth ...
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478
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USB 3.0 noise blocking GPS signals
We have designed a compact system that has:
Custom processing unit with USB phy and a USB 3.0 HUB (usb5744) with custom plastic USB connector.
USB 2.0 wifi module(external peripheral connected with ...
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2
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1
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EMI standards just for power on/off
I know the FCC has EMI/EMC maximums for connected emissions into the AC power cable while electronics are on.
But, are there FCC requirements on the brief connected emissions/bursts when the ...
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Where to connect case/USB shield to PCB ground?
I am currently designing a modular device for signal acquisition and signal generation. This is not a professional/commercial device. I am only building it out of interest and to learn.
Nevertheless, ...
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how to determine max peak of switching regulator in frequency domain (radiated emission)
I want to know how do I determine what should be the switching regulator peak in frequency domain(Radiated emission) , and where should I measure (Output or on inductor , capacitor).
Lets do below ...
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EMI Filter For Low Power SMPS
I've designed a 1.25W buck converter which is fed by 220VAC(85-265) and has a 5V output. Now I'm trying to design a EMI input filter for it. I don't have a PE connection so I didn't use a CM filter so ...
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Designing a mains powered device in metal chassis, EMC/EMI/ESD/safety considerations for CE testing
I hope this topic is not too broad. I will formulate it as specific as possible.
I have read many articles and guides about EMC testing, but I am still unsure whether I am overlooking something ...
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LM2576 vs modern step-down switching regulators - EMC requirements and other differences
I'm looking for some cost reduction in my design and I want to replace TPS54302 with LM2576 or LM2575.
In my case - switching regulator works as a pre-regulator with 12-24V input and ~6V output, ...
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Why are the coupling capacitors needed in this DCM converter?
I have a 48V power supply which needs to be converted to a 12V output. I want to achieve this by using the DCM2322 dc/dc converter.
In the Datasheet the following recommended circuit is given:
My ...
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Where exactly earth current flows-SMPS/DC-DC and DC-AC
Ashamed to ask this question after having lot of experience in Converter designs. i always heard and learnt from Sr. Mentors that For better EMI performance we need to give path for conducted noise(...
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Far field simulation results
I am trying to study the radiated and conducted EMI fields of my PCB using ANSYS SIwave. I did the DC IR drop analysis, and that was okay. Next I did the "Compute Near-field" and "...
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What could potentially affect some specific LoRa frequencies among others and how to mitigate it?
I have started a small LoRaWAN network. I already have setup:
1x LoRaWAN gateway (LAIRD RG186, using EU863-870);
4x T/RH Nodes (Dragino LHT65, same standard);
LoRa ...
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2
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709
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GSM noise from a 2-layer PCB with SIM800C
I've designed a 2-layer PCB that contains a 12-5V buck converter (P2576L-50 - a Clone of the LM2576), 3.3 (AP1117-33) and 4V (MIC29302WU) shunt regulators, an STM32 micro and a SIM800C GSM module.
...
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559
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Pulses counting problem from npn proximity with interrupts in arduino
I am interfacing an open output npn proximity sensor with Arduino nano. I have used very silly approach of voltage divider as I was not sure that in open output sensor you can get whatever voltage you ...
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answer
186
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Inductance value of PI-filter connectors?
I find myself in the situation of being forced to use filter connectors to solve an EMC issue very late in the project. Normally, this should of course be solved in circuit design, but as projects and ...
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781
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Flyback Transformer - Grounding the Ferrite Core
Today I dismantled (I hope this is the correct verb) a flyback transformer. The thing that I've never seen is that one end of one of the windings is "glued" to the ferrite core (Before you ask; yes, ...
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What are the relations between analog transmission frequency and multipair cable types?
My question is a little theoretical about multipair cables.
I want to have some basic understanding about the relation between the multipair cable types and application frequency, length and and EMI ...
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677
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EMC Filtering for BuckBoost LED driver
I'm designing a Buck boost LED driver using the ZXLD1370 IC. the circuit works but as one engineer said ("its easy to design a circuit but difficult to get it to pass EMC).
This is where my problem is....
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How does this diode improve the common mode conducted noise?
This image was taken from UCC28881 (page 16)
The desciption in the body says:
A half-wave rectifier is chosen and implemented by diode D2 (1N4937). It is a general purpose 1-A, 600-V
rated diode....
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423
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Deliberate Shoot-Through in H-bridge for EMI reduction
today I was analysing an H-bridge driver circuit in a commercial product which is used to drive a DC motor (approx 24V/4A) over an unshielded cable with about 1.5m length. When I did a simulation of ...
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Shielding effectiveness calculation
From The Basic Principles of Shielding:
Apertures, or holes, have SE. The SE of an aperture and ultimately the
entire electronic enclosure is determined by the size, shape and
number of the apertures....
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Where to place a cooling fan supply capacitor
I want to run a ~2W, 12 VDC fan in an EMI-sensitive environment.
The schematic is shown below. Due to the spiky current draw, I intend to place C1 and C2 right by the fan connector, so high frequency ...
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601
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Impedance mismatch in LISN for EMI/EMC test
I am currently designing LISN for CE-102 test.The schematic of the circuit is provided below.
When I connect the circuit to the network analyzer the impedance is coming as shown below
expected graph ...
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Reducing EMI from PWM controlled Led segments
I am currently designing a product that has a ring of LEDs with 7 individually dimmable segments.(all together about 40 standard (blue/white)LEDs max 15mA each) the only supply voltage is 3.3v but I ...
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Ethernet MLT-3 signall probing
I am getting radiated emission failure in my system, where the emissions were out of limit (~5 dB) for frequencies 125 MHz, 175 MHz, 225 MHz, 275 MHz, 775 MHz, 825 MHz. This sounds like the odd ...
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Best placement of bridge rectifier to allow DC/DC convertor to become AC/DC convertor. Does this inhibit surge and EMI performance?
I am trying to use the power supply: CQB50W12-72S12 with AC power without degrading the performance of its recommended filter and surge components. 120VAC peak voltage is 169V and I am worried that ...
user298907
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EN61000-4-5 Surge protection of PCB power supply
I am trying to better understand how EMC testing is simulated and passed. The datasheet of the CQB50W12-72S12 says it pass level 4 line to earth 4kV; and +- line to line 2kV with just a TVS diode (...
user298907
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DC/DC converter noise reduction circuit
I have 4 MEAN WELL NID-100-5 in parallel to power 5 V digital LEDs.
They will each receive a maximum of 2 A @24 V (max. total 8 A) and will each output a maximum of 9 A @5 V.
The 24 V supply cable is ...
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Antenna factor vs receiver noise
I am trying to make sense of a radiated emission measurement according to CISPR25. According to that standard, there is a maximum average emission of 10 dBµV/m at 1575 MHz (for GPS L1). I have doubts ...
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How to reduce noise on RS485 line?
The above picture is the output of a MAX485 IC, which is an RS485 transceiver. When the Cable comes near an AC power line, this kind of noise adds up. Without the presence of the AC main line, its ...
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IEC 61000-3-3 flicker for switches and relays
IEC 61000-3-3 shall be used for testing all 230V 50Hz AC devices with up to 16A current rating.
What about switches, relays, power plugs-basically devices that act as gateways between mains and actual ...
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299
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Conducted Emissions for Ethernet ports
A device has a DC power port as well as 2 Ethernet ports. One of the ethernet ports supports PoE++. Basically, the EUT can be powered through PoE.
I have a question regarding Conducted Emissions ...
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2
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Is a DC blocking capacitor required between a GPRS modem and the antenna?
tl;dr
A tracker device which sends GPRS telemetry has EMI issues. The original design had the antenna connected straight to the "ANT" pin of the GPRS chip. When a "0R" resistor on ...
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Why do I have higher noise at far end of a DC power cable even when unplugged at that end?
I have a 750W DCDC converter that is putting out 24v. The converter has a stated ripple max of around 600mV and when measured directly at the output (scope lead tip pin the the output, lead ground ...
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How much of my mixed-signal PCB should I shield with a Faraday cage?
I'm designing a PCB with an AFE (Analog Front-End) for measuring/recording bipotentials and I'm trying to determine how much of the circuit I should shield with a Faraday cage. At the moment, I'm ...
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Shielding issues with RJ45 connectors
I've been dealing with a pretty nasty radiated emissions problem at work and I've pretty well exhausted any list of potential solutions/mitigation tactics to resolve this given the design constraints. ...
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Switching power supply: spontaneously resetting
I have a project that uses an AC-DC switching power supply (ECP180PS28). The output of this supply is used directly, as well as being fed into a 5V switching power supply (based on the LT8612, running ...
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What is the correct arrangement of the EMI filter?
I want to design an EMI filter for the input side of a PFC converter. there are various topologies for EMI filters. in some cases, the CM filter is located on the network side and the DM filter on the ...
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Can multiple return paths cause EMI problems?
I am working with a 4-layer board (Signal - GND - PWR - Signal).
The power layer uses routed power so that each chip's power rail can be isolated. Layers 1, 3, and 4 have ground pours and stitching ...
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