Help needed regarding burning of ground

[viswaadithya]

Hi all,

I am currently working on the speed control of a DC motor by PWM using a microcontroller. The speed control is achieved by means of 8 mosfets connected in parallel. While the motor was run and tested, the ground of microcontroller PCB burnt. Am using common ground for all the PCBs. I need to know what the problem is? Is it because of the common ground? Why is the current taking the path through the Microcontroller board rather than through the Mosfets.
Kindly help me in this regard

 

[FvM]

Why is the current taking the path through the Microcontroller board rather than through the Mosfets.

Because you wired it that way, I fear.

 

[cameo_2007]

check pcb ground layout, spacing of the tracks and thickness , common grounding points, proper ground planes .

 

[howie]

Try using different ground assigments for every ciruit block and merge it with a bead inductor or ferrite bead. Originally, bead inductors are used to suppress noise where other conventional noise suppression devices cannot be used.There are different types of ferrite beads:

1. Ferrite chip bead inductors
2. Taped surface-mount
3. DIP shielded type bead (thru hole)
4. Ferrite chip bead array (array of chip bead inductors)

But it is also used in having different grounds merge into a common ground.

Also check your copper traces, your trace might be to thin or maybe you have wrong connections.

(See figure regarding bead inductor)

 

[siongboon]

I think you may have routed incorrectly.