Hello,
I'm designing a so called speed-shift for my road-racing motorcycle and I'm having problems with EMI going through my driving stage and back to the MCU (P89C51RD2) output port and making the port trigger by it self.
There is really no other problem than this, I have even tried putting the sparkplug directly over the MCU without any further glitches.
So the problem lies in my way of driving the final stage. I’m using a common BC547 transistor to drive a Infineon BTS-441 high side switch, I have placed a 0,1uF cer cap on the base of the BC and this helped a lot but I’m still having big problems. Can anyone tell me how to make a good filter for my MCU output port? I would like to keep my BC as a driver as I have etched the PCB with that in the layout so could I maybe just add a tranzorb or something like that?
HELP!!
/Roger Johansson