New to DRV 8811

Hi Devidas,

Thank you very much for your kind words! We are very excited about the Over Current Protection on our products, which definitely offer enhanced reliability to all of our customers across the platform.

On the DRV88xx devices, there is no need to add any form of external components to protect the device against deadly shorts. The feature is internal.

With regards to soldering, do you mean you will be soldering these devices by hand? That should be no problem. I do it all the time and the process is rather simple and effective as long as you have the right tools. You can find a visual guide here: http://www.youtube.com/watch?v=WliyehhveUk&feature=channel_video_title

Basically you will need a hot air gun. They can be anywhere from $100 to $3K and like always you get what you pay for, but in this case, $100 is plenty. That is the one I have at home and it has been working for the past year with no issues whatsoever.

My preferred method is to use the soldering iron to put some solder on the power pad. Then, with the heat air gun, I melt the solder and place the device on top. The device is cold so it will solidify the solder before it actually attach to the board. Apply some more heat and the device will yield. Then you can use your soldering iron and a fair amount of flux, to get the pads soldered in place.

It is very important to observe a requirement, however. These devices can not be soldered into the board if they have been exposed to humidity as the chance of delamination increases. If delamination takes place, then the power pad becomes dettached from the die, which implies a massive growth on the thermal impedance and considerably power dissipation degradation. You can consider the device damaged once this happens, as it current capability will plumet. Hence, it is crucial we avoid delamination at all costs.

What needs to be done is to solder devices on the board shortly after they are removed from a baked and packed bag. Devices will come with a humidity sensitive card board and as long as the humidity levels are low, the device will have up to 3 weeks to be soldered in a board. After three weeks, the devices must be baked again. Baking conditions are 8 hours at 125C.

Hope the info helps! Best regards,

Jose Quinones

Thank you Jose,

You have given satisfying and to the point answers.

Looks like I could be switching to 8811...

And it may increase my confidence in mini stepper drivers. So that my production goes up :-)

But I am a bit worried about the delamination, you mentioned. Seems I need to be careful before soldering.

Especially here in India, we have lots of moisture now the months of monsoon season.

Should I bake the first set of sample ICs as well ?

May I suggest, that TI takes some remedial steps so that this delaminations does not occur at all ?

Thanks again, TI is really costumer friendly.

Devidas

Hi Devinda,

Glad I was able to help with the first set of questions.

When it comes to delamination, we strive to make the devices as robust as possible. However, this is an inherent property of Power Pad devices. Due to the construction of said topology, the most efficient thing to do is to solder the devices as soon as they come out of the bag. This is why we take the most care when it comes to packaging these units and ensure a good quality device can be delivered.

I am not certain there is much that can be done to fully eliminate this behavior. Devices will have different MSL ratings and some of them will require immediate soldering, whereas other can withstand humidity for a longer time.

That being said, the solder before 3 weeks is a recommendation (one I would follow as much as possible), but does not imply you will get delamination if the suggestion is waved. However, if you do get the delamination, then the results are not appealing at all, since your thermal impedance increases considerably and the device is adversely affected for good with no possibility for recovery.

I can not say what the humidity levels on your region will imply in terms of chances for delamination. All I can say is that I think it is good practice to eliminate this variable as much as possible.

If you want to be sure, I would bake the devices at 125C for 8 hours. It is the best way to make sure delamination is a non existent threat. If they are coming from a sealed bag, I don't see a need to bake. They come with an indicator that tells you how much humidity they have been exposed to. If I recall, pink implies a need to bake, whereas blue indicates devices are ready for soldering.

Hope the info helps. Best regards,

Jose Quinones

Hi Jose,

The biggest thing I like about TI is customer friendliness. Availability of free samples quickly and its technical support is very helpful to any new development.

Now my PCBs are in process. I will write  / report again after the device is fired up :-)

If it works well, I am inclined to switch to 8811 instead of A3977.

Thank you again for the great replies.

Regards,

Devidas Bhonde