AnswerBun.com

Electro magnetic interferences (EMI) generated by power circuit reset low voltage integrated circuits (ICs)

The main question here is (explanation will follow):
Is there a way to filter out low voltage oscillations (>10MHz) on pins that have to stay high for the system to function? Oscillations are induced by EMI emitted by power circuit during relay bouncing). RC filters 100Ohm/100nF did not work. Traces are ~50cm long.

[Explanation]:

I’m currently struggling with proper EMI filtering for the low voltage control circuit that is responsible for switching on/off high voltage capacitors using relays.

I realize that the low level part of the circuit has a bunch of design flaws (e.g. the logic signal between uC and shift-reg could’ve been arranged into a differential pair). But currently I’m trying to figure out a way to modify the circuit with as little PCB modifications as possible.

Here is the essential part of the setup:
enter image description here

Power circuit is operating on fairly high voltage and current, but I don’t care about the quality of power of this circuit, moreover I cannot modify it.

The only issue I have to deal with looks like this (the description will follow):

enter image description here

  • Yellow – Power circuit voltage
  • Blue – Power circuit current
  • Green – logic signal (EN or CLR, see schematics)

Green signal represents EN or CLR; it is a CMOS 3.3V open-drain pin. When voltage falls below certain treshold (I guess 1.8V) it is no longer high, therefore the shift-reg resets. It cannot reset.

Electrical Engineering Asked by Krzych on December 27, 2020

0 Answers

Add your own answers!

Related Questions

AVRDUDE does not recognize USBasp device

3  Asked on December 5, 2020 by bas

     

Adding switch gives an error in Proteus

2  Asked on December 4, 2020 by sizu-taylorventuresllc

 

Higher than expected voltage in RC low pass filter

1  Asked on December 2, 2020 by vladimir-martynenko

 

Op-Amp as an error detector

0  Asked on December 2, 2020 by beatriceuk

         

Fine delay tuning using phase interpolation

0  Asked on December 2, 2020 by sahithi

     

MicroSD card stuck after CMD8, responding 0x5 before next CMD is issued

1  Asked on December 1, 2020 by diego-colombo

   

Water damage repair on solders

0  Asked on November 30, 2020 by anonymus51

     

Serial comms not reaching 0 V

0  Asked on November 28, 2020 by sanjo

       

Cause a voltage drop of about 1V

3  Asked on November 28, 2020 by michael-brown

     

Ask a Question

Get help from others!

© 2022 AnswerBun.com. All rights reserved.