Limit current of L6206 bridge driver

I'm currently building my first stepper motor driver, a bipolar stepper, 4.5-48V 1A phase current with 4.5 Ohm phase resistance. I've built the circuit of the L6206 following the "Typical application" in the data sheet and controlling it with an AVR ATmega.

Basically it works fine, but the current is much too high. At 12V my 2.5A power supply switches off and the L6206 gets hot very quick. At 7V the current at stand still is more than 1.5A, running it is at 1A.

So I suppose I have to limit the current, but I am not sure how. The datasheet mentions an integrated PWM current control but I can't find any further information on how to use it. It explains how to the overcurrent protection can be used to roughly regulate the load current what I have tried, it works but the motor then runs choppy and I feel sorry for it.

Another thing I don't understand is why the driver still works if I remove the charge pump?

$${12V \over 4.5\Omega} \approx 2.7A$$