Inhibit vs phase chopping

[stragenmitsuko]

Could somone explain the adavantages and disadvantages of these two
chopping methods .
Also calles fast vs slow decay if I understand correctly .

The story behind this question .
I'm building , or maybe better I'm trying to build , a 1/4 step driver .
Using a L6506 current controller , a 1 bit DAC , and the well known L298
as a driver . A gal 22V12 will produce the necessary logic .
I kow there are chips out there that will do the job , I just like to design something myself . And using a gal has several other advantages like e-stop and synchronised limitswitches

The problem is that wathever I do , the L6506 goes out of control , and the phase current drops to nearly zero as the voltage is increased beyond .
the maximum allowed stepper voltage .

So I've read that fast decay offers a better current control wich might solve my problem , but also produces a larger ripple .


Secondly , I've seen on some datasheets that an RC chain is put across each stepper winding . Is this a substitute for the clamping diodes , or do they have a different function .

Thx

Patrick


Picture shows a not yet finished prototype .
The basic idea is to use standoffs to mount the pcb on the back of a nema23