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PWM signal noise problem

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psivamanikandan

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I created PWM signal in dsPIC30F3011 and i am getting these waveforms . There are spikes during off period of value around 1 volt. So is that a problem??
Because i am going to connect this to a buck converter. So if both high side and low side PWM turned on at the same time it will blow the devices. So i just want to confirm this spikes won't create a problem.
 

Hi,

show us a scope picture of the spikes (both channels in one picture)

Show us the complete schematic and where exactely you measured the signals.

Klaus
 

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IMG_20170308_133828_HDR.jpg
this is the wave form i am getting
 

Hi,

Please post all requested informations.

* It may be a schematic problem
* It may be a layout problem
* It may be just a measurement problem (So the problem does not really exist)

I hope this is not a breadboard circuit. (I don´t think a breadboard is suitable to verify such circuits)
You need a PCB with GND plane and proper signal routing.

Klaus
 

We are seeing this signal directly on the ic pin. This spike is negligible or not??
 

The spike is negligible.
 

The problem is after the gate driver that same small spike is reflected and its killed the igbt. If i use negative voltage at gate driver if there is any possibility to overcome this problem?
 

The spike may not really be there, it could be a problem with your probe, or how/where your probe is grounded.
Try connecting the tip of your probe to ground and see if that spike is still there.
If it is, the spike may not really be on the gate but only appear that way.
 

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