DC Motor driver interfacing problem Atmega32 Board

Hello !

I want to drive 24V/5A DC motor with Atmega32. So bought motor driver having 24V/20A rating. But i am facing some issues :

1. When i connected Atmega Board with Motor driver and connected 24V supply to driver input, motor worked fine. But after that when i turned off power supply to Atmega Board, I observed that Power indication LED on board was still glowing as well as motor was rotating.
Is it due to Back EMF ?

2. To solve this, I connected diodes in series to the connection between Board to driver, to avoid Back EMF. It was a success. But after few seconds driver was blown with fumes coming out.

(Note : I maintained proper input to drive, i.e 24V. Didn't cross that mark.)

So my question is how to stop Back EMF as well as save the driver ?

Thankks.

A spinning motor becomes a generator. I believe this is like counter-emf. A changing flux field produces electromotive force.

However when I have seen motor experts talk about 'back-emf', it is an electrical spec inside a motor when it is under power with a load attached (I think).

In generator mode, the motor produced unknown voltage and current levels. Your board and/or driver was exposed to this.

It does not sound as though diodes were a successful safeguard. The current did not reverse direction, so they did not stop any current.

If you were to put a load on the motor, it will stop much more quickly after you cut power.