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enter image description here I was working with STK6714AMK4 connected with arduino to make a stepper move with the change of a potentionmeter resistance (stepper knob).

The motor at first worked well but didn't respond to the potentiometer. Anyway, One day after that, I powered the circuit again but the driver got so hot and the motor held at its position with some noise. So, I disconnected it and tried again but the driver wasn't working (I tried the stepper alone and it worked). So, what could be the reason? Can unfiltered power supply destroy such a circuit? (I connected the circuit as shown but didn't connect any capaitor in my circuit)

Datasheet

enter image description here

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  • \$\begingroup\$ Heat could destroy it. Define "driver got so hot". What temperature? What power were you dissipating in it? What thermal resistance was the heatsink you were using on it? Was it in still air or did you have fan cooling? Are you following the heatsinking recommendations in the datasheet? \$\endgroup\$ – Brian Drummond Oct 19 '16 at 16:27
  • \$\begingroup\$ @BrianDrummond I could touch it but it's not comfortable, The stepper i connected is rated for about 4 volts but in the datasheet it requires 24V at Vcc2. So, I connected the common centertaps with 24V and didn't connect any limiting resistors depending on the IC current limiting function... Anyway, I will take a look at the power dissipation in the datasheet and try to figure out what went wrong.. \$\endgroup\$ – iMohaned Oct 19 '16 at 16:48
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Motors behave like inductive loads. Suddenly reducing or interrupting current supply on a motor will generate a voltage spike (called flyback) on it's driving lines. The driver can survive spikes, but not forever. The flyback should be eliminated with a diode. You can read more about it on the Wikipedia.

Note: since you can drive motors in two ways, I suggest adding transient-voltage-suppressor (TVS) diodes (one between A and A\, one between B and B) which can elmininate flyback in both ways.

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