I'm playing with a L6506 Current controller for stepper motors.

http://www.st.com/stonline/.../l6506.pdf

This is how I have the chip wired up right now.



And the power stage to the motor.



The datasheet says the L6506 can be used with descrete transistors like I have it here, but none of the application notes I've found show any examples of it. Most show how to use it with a L298 or similar.

My stepper motor has 1 ohm phase resistance and is rated for 1 amp/phase. The stepping sequence I use is where 2 phases are energized at any one step, that's where the 2 amps comes from.

I_Peak = V_Ref / R_Sense or 2 Amp = .66 V / .33 ohms

However, when the circuit is energized, I'm measuring about 4.62 amps through the fuse and my R_Sense voltage is about 1.5 Volts. Needless to say R_Sense, which is rated at 3 watts, let some magic smoke out.

I'm not sure if I can tie both of the V_Ref's and the V_Sense's together like shown above or not.

Can anybody shed any light on what I've done wrong that's causing the current to be higher than I need?

Thanks

Jon