Sonsivri

I just finished the drawing for a high power bipolar stepper controller. Thanks to the friends who helped me in designing stage.

It is based on popular L297 but the power side will be driven by the power MOSFET IRFZ44. My basic requirements are as follow -
Supply: 40V - 50V
Current: 6A - 10A

I really love the MOSFET, it will fulfill my requirements. There are some additional features in the schematic, I'm giving a short description of them.

1. Motor current will be reduced in idle  mode. It has been achieved using NE555. I'm also thinking to use a PIC so that I can modulate VREF.
2. The circuit will provide equal torque in Half stepping mode so there will be no difference in torque for Full/half step mode. It has been achieved using an AND gate (7411/7415).
3. It will be a 3-axis board. I'll use oscilator only for one axis and just use the SYNC option (L297) for rest of them. It will significantly reduce the noise.

Most of the parts/components I've already in hand except the half-bridge driver IR2104, which I just ordered in ebay. By this time, I'll try to draw the PCB. I'll be glad if anyone can help me to draw the PCB (in Eagle).

Any comments or suggestions will be welcome.

Any reason you did not put diodes across those beloved MOSFETs?....the motor inductance may kill them, and if so, that ain't love.
:-)

buddy, you're hurting my beloved MOSFET's!  ;)
don't worry, IRFZ44 has the diode inside. external diodes are not mendatory.

Body Diode unreliable , do not trust !
Fast diode should use

At least 1/16 micro-step must be

exactly

Reverse Diode is a parasitic result of MOSFET fabrication, but in the IRFZ44 as you can see in their datasheet it has spec comparable to that of a fast diode (trr = 47nS @ 40A forward current), so, for this application it should work with no problem at all.

regards,

c

yep. that's why I didn't add extra diodes.

Thanks buddy.
Floting control pin was a mistake during Eagle sketch. That has been fixed later but I forgot to update here. I'll upload it when in home.

You will need some caps across VMotor to ground, electrolytic + mylar combination is good.

Diodes at DS of the mosfet is not mandatory, but you will need to design an excellent layout with minimum parasitic inductance.

There is a good tutorial for motor driver layout from the maker of Geckodrive, i've posted it here:

http://www.sonsivri.com/forum/index.php?topic=24820.msg84827#msg84827 (http://www.sonsivri.com/forum/index.php?topic=24820.msg84827#msg84827)

-ichan

Thanks Ichan.

The project is on-hold. I'm just waiting for the samples from LSI. Some (improved/pre-release edition) LS8290 will be delivered this week. This is basically the same chip of L297 but with microstepping capability.

Can you please post the datasheet for the microstepping LS8290?

thanks

Here it is.
There is also 8291 in pipeline and they will send me the PR sample when available.