New answers tagged

1 vote
Accepted

Board-To-Board Connector : Shield Pins : Voltage Bus?

That is a hybrid connector (signal contacts plus power contacts). They are not shield contacts. The power contacts are available to carry the power supply current. So, yes, do use one for power and ...
Davide Andrea's user avatar
0 votes

Ethernet controller EMC failure

The W5500 uses PLL to generate 125 MHz using 25 MHz crystal. Digital part and PHY are fed with this frequency. The chip is relatively hungry for the current as it contains PHY inside. And it is the ...
Anonymous's user avatar
  • 7,098
0 votes

EFT on powersupply AC input

Medical grade supplies usually are designed for low leakage to ground so it's quite plausible it would let the EFT go through. Also to pass EFT it only need to keep working itself nobody says it can ...
Lorenzo Marcantonio's user avatar
0 votes

Should EMC/EMI tests be applied to power transformers or not?

You have to first look into capacities of transformer and ratings. Small and routinely used rating transformer may not have been preferred for these testing's. Even though all defense and Navy ...
Anantrao's user avatar
3 votes
Accepted

Watching an open-collector input without disturbing it

Your "black magic box" must be drawing some current through R2 and the transistor base-emitter junction, turning the transistor on. You could try adding a diode between the black box and ...
GodJihyo's user avatar
  • 23.4k
1 vote

4-20mA ferrite bead position

Pigtailing a shield isn't exactly the best way to reduce noise... however: Most probably the UHF noise is entering in common mode on the cable (maybe through the shield) and rectifies inside your ...
Lorenzo Marcantonio's user avatar
2 votes
Accepted

What mode does the stm8 switch to during EMC testing?

Is there any way to get out of this state? Other than cycling the power probably not. The trick here is to avoid going into this state. Entering that state is due to poor/weak layout on the circuit ...
Andy aka's user avatar
  • 457k
1 vote

Is there a way to reduce harmonic current for a single phase VFD without using an active filter?

An option to reduce inductor size could be PFC with partial switching, but need many efforts that probably make no sense against common filters. See figure from Toshiba PFC circuits An active PFC (...
Bravale's user avatar
  • 1,577
0 votes

Should unused connector terminals be connected to ground?

Are you planning on using these pins in future revisions of the board? If so, and you ground the pins, then consider what happens if the signal-source board for a new revision of this sink board is ...
CSM's user avatar
  • 171
2 votes
Accepted

Should unused connector terminals be connected to ground?

For EMC purposes, you might consider grounding (or VCC or any other RF ground / supernode) to control ground-return paths, or increase density of ground around priority signals. This doesn't mean too ...
Tim Williams's user avatar
  • 34.2k
2 votes

Should unused connector terminals be connected to ground?

If the pins are not used, I would just leave them unconnected.
Peter Bennett's user avatar
1 vote

EMC-EFT problem with touch screen

There often is a rectifier effect at the input of integrated circuits. The internal protection diodes rectify RF signals coupled into wires. The IC sometimes reads this as logic high level. I added R1 ...
Jens's user avatar
  • 6,934
1 vote

EMC-EFT problem with touch screen

Without seeing much more detail of the circuit and what actually fails it's very hard to say. I would start off by adding transient suppression from each signal where it enters the PCB (so if there's ...
Robin Iddon's user avatar
2 votes

EFT generator circuit

Some approx. numbers. SiC MOSFET, reverse transfer capacitance 100 pF. Drain voltage 1000 V. Miller charge is thus 100 nC. We need to fill this in 6 ns, so we need about 16 A of gate current. If we ...
tobalt's user avatar
  • 22k
1 vote
Accepted

What are the limits for broadband (BB) and narrowband (NB) radiated emissions?

The document shows two graphs, you only posted one. The left one is concerning "broadband" and the right one is concerning "narrowband". These are directly taken from the ...
Lundin's user avatar
  • 20.2k

Top 50 recent answers are included