[joprinz]

Hello Everyone,

I have been using the L297/L298 based stepper drivers. So far it has worked perfect except for the fact that it can only provide Max 2A per phase to the Stepper. Somehow most of the High Torque Steppers are rated 5A and more. I did some reading over here and found a few people using the L297 to drive a MOSFET H-Bridge and thus providing Higher currents to the motor. However I am not able to find a scematic for the same.

I hope someone can provide me guidance for the same. Any Schematic/Circuit idea/suggestions/opinions regarding the same is highly appreciated.

Please Advice!

Thank You,

Joe!

[Almaz]

Unipolar Stepper Motor Driver with Chopper Action, using an L297 driver IC http://www.pchilton.co.uk/index.php?..._stepperdriver

[joprinz]

Thank You Almaz.

I'm using steppers in Bipolar mode. I'm not very familiar working with discrete H-Bridges. Do you have a similar design for a Bipolar Stepper?

Thank You!

Joe

[irving2008]

Thank You Almaz.

I'm using steppers in Bipolar mode. I'm not very familiar working with discrete H-Bridges. Do you have a similar design for a Bipolar Stepper?

Thank You!

Joe

Joe, I am also working on a design for using L297 or LS7290 (if I can get some) with discrete MOSFETs. The LS7290 datasheet shows an example using LS6203 drivers which is good to 4A but I am looking at using hi/lo side drivers and some gating logic to replicate the internal functions of the LS6203 with discrete parts to get to 6 or 8A eventually.

I've not found any working schematics either...

[joprinz]

Joe, I am also working on a design for using L297 or LS7290 (if I can get some) with discrete MOSFETs

Hello Irving,

Well, i got my hands on the LS7290 thinking it would provide me Micro Stepping. But there is an issue with the LS7290 chip with its Micro Stepping Mode.

Here is the Tech Note they sent me:

Duty Cycles of active-low Outputs, INH1/ & INH2/:

The duty cycles of INH1/ and INH2/ outputs are fixed per table 2 of the LS7290 datasheet.

The SENSE1 and SENSE2 inputs are provided for over-current protection only, not for chopping control of the drive outputs.

In any stepping mode other than the full-step and the half-step modes, if the inhibit outputs are truncated due to the SENSE inputs reaching the VREF level, the fixed duty cycle ratios of the INH1/ and the INH2/ will be disrupted leading to motor misstep.

Therefore, in modes other than the full-step and half-step, the SENSE1 and SENSE2 inputs should be tied to ground and the VREF input should be tied to the positive rail. Under these circumstances, if over-current becomes an issue, it can only be resolved by lowering the motor supply voltage.

In the full-step and the half-step modes however, since the fixed duty cycle ratios for the two inhibit outputs are 100%-0% and 70.7%-70.7%, the SENSE inputs can be utilized for chopping the INH1/ and INH2/ outputs, without disrupting the duty cycle ratio. Therefore, in full and half step modes SENSE input chopping can be used for motor current regulation.

When the SENSE inputs are used for output chopping, the INH1/ and the INH2/ outputs are terminated (switched low) when the corresponding SENSE input becomes equal to the VREF. The maximum voltage at VREF= 3V, when chopping is used.

For fixed PWM, the duty cycles in table2 are adjusted within a 32us window based on 8MHz clock. For reference, this will translate to 22.6us on and 9.4us off for a 70.7% duty cycle.

For most applications its best to run the Steppers at a Higher Voltage than the rated Motor voltage to get Higher torque values at higher rpms. And I guess the LS7290 is not suited for High Voltage driving in Microstepping mode. Full Step and Half step can be achieved by just using the tried and tested L297 itself. So I think for a CNC application using the LS7290 is not a good idea (Jus my opinion).

And as far as the MOSFET Drive circuit for L297 is concerned I think the Unipolar version is available in the LS7290 Datasheet itself. But I have very little experience in working with Discrete MOSFETS. But I'm sure there are plenty of experienced people here, who could modify the Unipolar design to a Bipolar setup with ease.

Here is the LS7290 Datasheet.. Please check Page No: 7 for a MOSFET driven Unipolar setup.

Hope someone can help us with this...

Thank You,

Joe!

[irving2008]

Joe...

Hmmm thats disappointing, as I just asked for some samples. Did you get a sample or paid for it (and if so, how much?).

I wonder if the solution to the chopping is to add an external chopper such as the L6506

[joprinz]

Irving...

well I think you should be able to get samples...There is a Sample Form on the LSI/CSI site. But i got it from someone who had imported a couple of hundred of them. I got 5 of them for about 8USD each... its almost double the wholesale price on them (I think the wholesale is about 4USD if U buy about 100 chips) but i just wanted to experiment with them before i order big numbers... So I guess the price was ok...

n Yes...it is a lil disappointing. I was soo excited to have Finally found THE ANSWER to My MicroStepping Needs. Like you said we could probably use the L6506 but again that be jus adding one more stage into the design. I personally think the lesser the number of stages the better.

n btw have U checked the new L6205/6 Dual H-Bridges from ST??? They are rated 2.8A but they can be run in parallel to get 5.6A. if you don wanna go beyond 5A i think the L6205/6 would be sufficient.

But finding a MOSFET H-Bridge design to work with the L297 would be still a Better Solution. I wonder Y noone seems to be interested in doing that even though the need for a Bipolar driver above 5A is quite Big considering everyone using Bigger NEMA 34 and above Steppers offlate...

Joe!

[irving2008]

Irving...

well I think you should be able to get samples...There is a Sample Form on the LSI/CSI site. But i got it from someone who had imported a couple of hundred of them. I got 5 of them for about 8USD each... its almost double the wholesale price on them (I think the wholesale is about 4USD if U buy about 100 chips) but i just wanted to experiment with them before i order big numbers... So I guess the price was ok...

n Yes...it is a lil disappointing. I was soo excited to have Finally found THE ANSWER to My MicroStepping Needs. Like you said we could probably use the L6506 but again that be jus adding one more stage into the design. I personally think the lesser the number of stages the better.

n btw have U checked the new L6205/6 Dual H-Bridges from ST??? They are rated 2.8A but they can be run in parallel to get 5.6A. if you don wanna go beyond 5A i think the L6205/6 would be sufficient.

But finding a MOSFET H-Bridge design to work with the L297 would be still a Better Solution. I wonder Y noone seems to be interested in doing that even though the need for a Bipolar driver above 5A is quite Big considering everyone using Bigger NEMA 34 and above Steppers offlate...

Joe!

Joe,

I checked out the L6205/6/7 and they are indeed better suited to being paralleled up for 5A but higher than that requires a discrete solution. I would look at using something like four L6387E hi/lo drivers with some gating logic (needs 8 AND gates and 4 inverters), although there are other variants of the 6387 that might be better because they use less logic gates. The 6387 will drive just about any MOSFET you can find.

The 6205/6/7 aren't new by the way, they date back to 2003 although the data sheet just had a revamp.

rgds
Irving..

[jit_singh_tara]

hey joe,
I am too desperately looking for l297 and mosfet based h bridge driver,if you get any useful schematic please let me know.

Jitender singh

[leaveme]

L6205/6/7 is not a multiwatt package. How do you heatsink it?

I still prefer L6203. It provides 4A RMS current, 5A peak current.

[arisov77]

... I am too desperately looking for l297 and mosfet based h bridge driver,if you get any useful schematic please let me know...

In Russia, collected under the scheme CNCMASTERKIT Forums-viewtopic-L297-IRFZ (who is its author - I do not know). Reviews of the work - positive.
Unfortunately, the ZIP-archive (3,3Mb - Scheme (Splan7), PCB (Sprint Layout 5) & Photo device) was unable to load here on the forum. Perhaps here we obtain Скачать файл - ХоÑ�тинг файлов - хранение файлов, беÑ�платный файлообменни� �º CncFiles

[dwalsh62]

Well, seems to be lots of talk about all kinds of stuff that is available but impossible to locate a schematic that doesn't require hard to find components or assembly equipment not available to the average user and most of what is available is really unsuitable for general use when it has a limiting use factor based on the design.

The best concept for the CNC world seems to be a modular design and if you stick with discreet components you can build a driver for almost nothing.

If some one can provide a schematic (tried and true) that uses discreet components.

I am willing to consider producing a PCB and making it readily available at a reasonable price which will become property of CNCZone if someone can provide such a schematic.

The circuit must be for a bipolar (4 or 8 wire motor), support home, limit, dir, step and provide some current/voltage adjustment/protection.

The use of discreet components makes building the driver relatively inexpensive and allows a means of increasing current capacity by the addition of output transistors which would affect the overall cost by very little.

The posted russian schematic is something along that lines which can be made into a high-current capable device with little work but it needs some minor tweaks to provide the home, limit and protection so if someone has built this device we need to talk.

[FAXed]

Well, I really don`t know if this can help them : this is an Bipolar stepper driver 4A - 42V for 1 ax. This drive uses a couple of h bridges (L6203) but it dont provide some current/voltage adjustment/protection -I don’t have tested this board -

Stepper driver board with L297 and L6203

[john-100]

hi Joe ,

has any one used 1 x L 297 and 2 x L 298
to drive the stepper motor

one L298 ic used for each coil
channels 1 + 4 and 2 + 3 , paralleled

John

[AndersG]

"The circuit must be for a bipolar (4 or 8 wire motor), support home, limit, dir, step and provide some current/voltage adjustment/protection."

Can you please elaborate on the switches? This is normally handled at the software level, ie by Mach3?

[nastelroy]

hi Joe ,

has any one used 1 x L 297 and 2 x L 298
to dive the stepper motor

one L298 ic used for each coil
channels 1 + 4 and 2 + 3 , paralleled

John

Hello I'm newbie in CNC zone
I have little experience in making CNC, but I have more in stepper driver...

my first project:
one L297 + one L298 to drive 2 phase bipolar (4 wire) motor stepper.
result = good

second project :
one Atmega8 + one L298 to drive 2 phase bipolar (4 wire) motor stepper.
result = good

third project :
one atmega8 + two L298 to drive 5 phase bipolar pentagon (5 wire) motor stepper. ---> full step mode
result = good

fourth project
one atmega8 + three L298 to drive 5 phase bipolar pentagon (5 wire) motor stepper.----> full and half step mode
result = best

Some of this project are written on my blog
www.nastelroy.wordpress.com

http://www.nastelroy.wordpress.com/2...river-pentagon

I hope that will be a useful information.

Now I have some problem to make this driver with microstepping mode. And still cooking how to do it...

[AndersG]

OK. Having read through the LS7290 datasheet, I now see that it does not provide any real benefit over the L297. The LS7290, as others have pointed out, does not do Microstepping and chopping concurrently and chopping, however awkward, is often needed to get the required speed out of the motors.

That being said, I would probably consider the LS7290 for a full/half-step design, since it lets you control the blanking time digitally. This helps reduce squeal from the motors.

[leaveme]

...
second project :
one Atmega8 + one L298 to drive 2 phase bipolar (4 wire) motor stepper.
result = good
...

Welcome to CNCZONE.

I'm interested about your 2nd project. Did you do the current control in this project?

[nastelroy]

Welcome to CNCZONE.

I'm interested about your 2nd project. Did you do the current control in this project?

I didn't do that yet...I just emulate Atmega8 as L297. So the current is still constant.

But I will do this method in my last project (for 5 phase 5 wire pentagon stepper)...there are no chip that support microstepping for my motor stepper.

If you want make microstepping driver for 2 phase bipolar, there are so many chip that support this. Such as A3967SLB, A3977, etc

Have a nice Day

[dwalsh62]

I didn't do that yet...I just emulate Atmega8 as L297. So the current is still constant.

But I will do this method in my last project (for 5 phase 5 wire pentagon stepper)...there are no chip that support microstepping for my motor stepper.

If you want make microstepping driver for 2 phase bipolar, there are so many chip that support this. Such as A3967SLB, A3977, etc

Have a nice Day

None of those chips handle any real current, if it doesn't support at least 5A continuous then it's consider a toy driver.