Using drv8825 with external transistors to increase current

Hello everyone, I am new on this forum, so please warn me for my mistakes.

I am working on a project that is going to drive a stepper motor. I am trying to design a pcb that has wide current range driver for stepper motor on it. According to Pololu’s website, the highest continious current I can get is 1.6 A by using TB67S249 but I need 4.2 A for my project. So I planning to use H-bridges for each coil to increase current. I wonder if anyone ever tried this before or do you have any suggestions. I also wonder that will it be possible to limit current. I think the current across the coil should be 2xVrefxHfe
of transistors that i will use. Any idea could help.

Thank you.

It is not possible to modify the DRV8825, and high current H-bridges MUST be designed by experienced, professional engineers.

Several higher current stepper drivers are available on the web. The TB6600 is popular, but it is limited to 3.5 A continuous per winding.

thanks for your answer. I will give it a try to make this work. I am pretty sure it will work but the question is how efficient will it be?

Make what work?

I will add H bridges to output of drv8825 to increase current. Then analyze the output and modify the circuit

Do keep us informed of how it goes!

I will!