Build Thread- TI drv8824 45 V 3A and 1/32 step

[smartgsm]

Very nice chip...

but on google ... nothing...


http://focus.ti.com/lit/ds/symlink/drv8824.pdf
http://focus.ti.com/docs/prod/folder...nicaldocuments


Grega

[dandumit]

Great info , but - samples not available..
DRV8825 isn't mentioned at all ...

[eSilviu]

Originally Posted by smartgsm Very nice chip... but on google ... nothing... http://focus.ti.com/lit/ds/symlink/drv8824.pdf http://focus.ti.com/docs/prod/folder...nicaldocuments Grega

On datasheet writes "october 2009". so it should be out soon (at least as samples).
Looking at pinout, I can do a single side PCB, in less than 5 min.

[smartgsm]

i contact TI tehnical support.

Production for this IC is 2012.

[eSilviu]

Originally Posted by smartgsm i contact TI tehnical support. Production for this IC is 2012.

too bad.

[eSilviu]

Originally Posted by smartgsm Very nice chip... but on google ... nothing... http://focus.ti.com/lit/ds/symlink/drv8824.pdf http://focus.ti.com/docs/prod/folder...nicaldocuments Grega

News: IC is now "active", and samples can be aquired.
The bad news: IC is useless for CNC application:

FEATURES from Datasheet:
• PWM Microstepping Motor Driver
– Built-In Microstepping Indexer
– Five-Bit Winding Current Control Allows Up to 32 Current Levels
– Low MOSFET On-Resistance (0.7 ohm is HUGE resistance for a low voltage MOSFET!!!!)
• 1.6-A Maximum Drive Current at 24 V, 25°C (at the beginning it was supposed to support 3A !!)
• Built-In 3.3-V Reference Output
• 8-V to 45-V Operating Supply Voltage Range (as usual... but parametters are given at 24V)
• Thermally Enhanced Surface Mount Package (the same minuscule SSOP package, with hard-to-solder pins)

[TIChris]

Originally Posted by eSilviu News: IC is now "active", and samples can be aquired. The bad news: IC is useless for CNC application: FEATURES from Datasheet: • PWM Microstepping Motor Driver – Built-In Microstepping Indexer – Five-Bit Winding Current Control Allows Up to 32 Current Levels – Low MOSFET On-Resistance (0.7 ohm is HUGE resistance for a low voltage MOSFET!!!!) • 1.6-A Maximum Drive Current at 24 V, 25°C (at the beginning it was supposed to support 3A !!) • Built-In 3.3-V Reference Output • 8-V to 45-V Operating Supply Voltage Range (as usual... but parametters are given at 24V) • Thermally Enhanced Surface Mount Package (the same minuscule SSOP package, with hard-to-solder pins)

Hi eSilviu, I saw your comment about TI’s DRV8824 being unsuitable for CNC apps and wanted to post a quick comment.

I’m a product marketing engineer at TI focused on motor drive and spend a lot of time working with customers and apps engineers who work in motor control apps, giving me the opportunity to learn a lot about system requirements, etc.

The DRV8824 may not be appropriate for large machines (such as table routers and mills), but there are a fairly large number of very small CNC machines such as engravers, PCB mill drills, etc for which it could perform perfectly fine without having to pay more for unneeded (and unused) amperage. Also, I bet any plasma cutter will run nicely with the DRV8824 as there is no need for a lot of torque to drive the plasma head, since these tables are built by using either belts or rack and pinion mechanisms, which require less torque than the lead screw counterpart.

As for the specs, the DRV8824 was designed with 1.6A output as a target hence the higher Rdson. The confusion may be because the DRV8825 was also on the same datasheet when both devices were in the preliminary stages. When the DRV8824 was released we put it on its own datasheet and created a separate one for the DRV8825. We are still planning to release the DRV8825 targeting at least 2.5A Iout and with a power stage designed with 300mOhm Rdson FETs.

I’d be happy to answer any questions you have or if you want more information about the DRV8825 from TI’s website here’s the latest preliminary datasheet: http://focus.ti.com/lit/ds/symlink/drv8825.pdf

-Chris

[eSilviu]

Originally Posted by TIChris Hi eSilviu, I saw your comment about TI’s DRV8824 being unsuitable for CNC apps and wanted to post a quick comment. I’m a product marketing engineer at TI focused on motor drive and spend a lot of time working with customers and apps engineers who work in motor control apps, giving me the opportunity to learn a lot about system requirements, etc. The DRV8824 may not be appropriate for large machines (such as table routers and mills), but there are a fairly large number of very small CNC machines such as engravers, PCB mill drills, etc for which it could perform perfectly fine without having to pay more for unneeded (and unused) amperage. Also, I bet any plasma cutter will run nicely with the DRV8824 as there is no need for a lot of torque to drive the plasma head, since these tables are built by using either belts or rack and pinion mechanisms, which require less torque than the lead screw counterpart. As for the specs, the DRV8824 was designed with 1.6A output as a target hence the higher Rdson. The confusion may be because the DRV8825 was also on the same datasheet when both devices were in the preliminary stages. When the DRV8824 was released we put it on its own datasheet and created a separate one for the DRV8825. We are still planning to release the DRV8825 targeting at least 2.5A Iout and with a power stage designed with 300mOhm Rdson FETs. I’d be happy to answer any questions you have or if you want more information about the DRV8825 from TI’s website here’s the latest preliminary datasheet: http://focus.ti.com/lit/ds/symlink/drv8825.pdf -Chris

a quick answer, if you can:
Why use DRV8824 and not DRV8811 (wich is equivalent of A3977 from allegro)?! just because it has "Up to 32 Current Levels"?!

My opinion: there are other IC drivers for bipolar stepper suitable for CNC area. This is a minuscule IC, with low output curent, and high resolution. It may be well suited for some applications, but not for "usual" CNC. We are waiting for a IC to have 8-16microstep resolution, 3-5A ouptput curent/phase, and 40-80V. Or a good driver for MOSFET H-bridge (since A3986 is the only one from this area, and has it's flaws)

[dandumit]

Originally Posted by TIChris We are still planning to release the DRV8825 targeting at least 2.5A Iout and with a power stage designed with 300mOhm Rdson FETs. -Chris

Nice that you have tooked the time to discuss with us Chris ! That leads to good support.

As far as your planned product. You know what would be a bestseller here ?
A 4A-4.2A per coil driver.
Until 3A are plenty of options, but many Nema23 motors from market now are working on 2.8A or 4.2A.
Those Nema23 with 1.8-1.9Nm are on market on a budget price - it's missing a cheap option for a driver .

Daniel

[eSilviu]

Originally Posted by TIChris I’d be happy to answer any questions you have or if you want more information about the DRV8825 from TI’s website here’s the latest preliminary datasheet: http://focus.ti.com/lit/ds/symlink/drv8825.pdf -Chris

I would say that DRV8825 don't bring anything new and valuable (except microstep32). In fact, it will not be used at all by average CNC electronists because of small footprint. So don't expect to make too much money with that IC.
I use DRV8811 at this time, I'm satisfied with this IC. But making PCB and soldering that IC it's not for anyone.
I read between lines that TI has buyed some licences from Allegro. Maybe a better version of A3986 will make the difference. And a bigger footprint.. SOIC would be perfect!!!

[TIChris]

Hey Guys,

Thanks for all the comments. I have been on travelling the last few weeks but wanted to make sure I responded to all the questions.

First there was a question about what the DRV8824 offers over the DRV8811:

The big advantage on the DRV8824 over the 8811 is not only the extended resolution, but the ability to increas current capability just by switch the DRV8824 for a DRV8825 . Notice that we have built the DRV8825 so that it is pin to pin compatible with the DRV8824. Hence, the same board can be used for low current applications, as well as higher current applications, in this case CNC routers without a layout change. That being said, once the DRV8825 is released, it will be a stronger driver than the DRV8811 since we have integrated lower Rdson MOSFETs in the output stage.

There was also a question about going higher power up to 5A of output:

With regards to current, the DRV8825 will not get you to the 3-5A range you are looking for, but the DRV8828/29 will. We have an application note on how to interface two DRV8828 devices for up to 3A per phase or two DRV8829 devices for up to 5A per phase, by using an MSP430 microcontroller. We can provide you with Gerber Files, and microcontroller firmware. The application note details how to implement up to 256 degrees of microstepping, in case you want further resolution. We are working a second application note which details how to build an even cheaper implementation which will give you up to 32 degrees of microstepping at 50V and 5A per phase.

I’d be happy to answer any questions you have or if you want more information about the DRV8829 from TI’s website here’s the latest preliminary datasheet: http://focus.ti.com/lit/ds/symlink/drv8829.pdf

Also - feel free to join in the discussion at the TI motor driver discussion forum: http://e2e.ti.com/support/applicatio...s/default.aspx

--Chris

[eSilviu]

Originally Posted by TIChris Hey Guys, Thanks for all the comments. I have been on travelling the last few weeks but wanted to make sure I responded to all the questions. First there was a question about what the DRV8824 offers over the DRV8811: The big advantage on the DRV8824 over the 8811 is not only the extended resolution, but the ability to increas current capability just by switch the DRV8824 for a DRV8825 . Notice that we have built the DRV8825 so that it is pin to pin compatible with the DRV8824. Hence, the same board can be used for low current applications, as well as higher current applications, in this case CNC routers without a layout change. That being said, once the DRV8825 is released, it will be a stronger driver than the DRV8811 since we have integrated lower Rdson MOSFETs in the output stage. There was also a question about going higher power up to 5A of output: With regards to current, the DRV8825 will not get you to the 3-5A range you are looking for, but the DRV8828/29 will. We have an application note on how to interface two DRV8828 devices for up to 3A per phase or two DRV8829 devices for up to 5A per phase, by using an MSP430 microcontroller. We can provide you with Gerber Files, and microcontroller firmware. The application note details how to implement up to 256 degrees of microstepping, in case you want further resolution. We are working a second application note which details how to build an even cheaper implementation which will give you up to 32 degrees of microstepping at 50V and 5A per phase. I’d be happy to answer any questions you have or if you want more information about the DRV8829 from TI’s website here’s the latest preliminary datasheet: http://focus.ti.com/lit/ds/symlink/drv8829.pdf Also - feel free to join in the discussion at the TI motor driver discussion forum: http://e2e.ti.com/support/applicatio...s/default.aspx --Chris

So you are spinning around a hard to solder IC, with low curent output. There are allready many ICs that do this job. Adding another one (or two) will not be usefull to many people.

Why don't TI design a pre-driver for DRV8432? It will be like the pair L297+L298, but with better performance. This looks to me like a winning strategy.