Increasing the capacity of stepper driver ics
Increasing the capacity of stepper driver ics
(OP)
Hi all. I'm looking to increase the output capacity (current) of a stepper motor driver ic. Above about 4A, the only commercial units are complete "systems" on a board. So, in principle, how's this: Connect the existing outputs from the ic to a pair of comparators (with pull up/down) to clean up the signal, then use the comparators' outputs to drive high current fets. So I've added a "power stage". Any good, or am I missing something fundamental here? Steve.





RE: Increasing the capacity of stepper driver ics
You may also need additional clamp diodes as the original chip driver stages probably has these on board.
RE: Increasing the capacity of stepper driver ics
I concur with BrianG. A good healthy swing of the voltage
to the power fets should produce the required current drive
without comparators in the circuit. You might need a
small buffer amp in between, but I would suggest looking
at a simple semiconductor switch in the circuit instead.
Cheers,
Rich S.
RE: Increasing the capacity of stepper driver ics
RE: Increasing the capacity of stepper driver ics
For a given winding, do you drive with one FET or an H-bridge? If an H-bridge, use a FET driver chip that prevents shoot-through.
Be gentle to the gates. Even the big power MOSFETs can usually only handle a gate-source voltage of 20 volts.
RE: Increasing the capacity of stepper driver ics
RE: Increasing the capacity of stepper driver ics
Mike Halloran
Pembroke Pines, FL, USA