INA303: Current sensing amplifier choice

Hello, 

Thank you for your post. 

The INA303 is a unique device in that it offers window comparator functionality with an amplifier output. 

If you know your current range during operation, then this would become useful for ensuring your current operates within this range using the two ALERT outputs. 

If you only need an overcurrent detect then I would say the INA301 is an option with 700µA max current. 

I can help you with your design questions centered around the INA303 specifically as my team is responsible for the current sense amplifiers. 

I am also providing a breakdown of pros and cons of using different types of amplifiers for current sensing: Current sensing with different types of amplifiers | Video | TI.com

I hope this helps, 

Joe

Hi Joe, thank you very much. I'd found that video series, and indeed it is quite helpful!

My question is not specifically about the INA303 - the TI forum software requires/forces me to specify a single product when asking a question, but my actual question is more general in nature - I'm asking for advice about choosing a part appropriate for low-power use. 

While the DRV8311 is an appealing option I am considering, but it's not clear to me that the DRV8311 is as suitable for a battery-powered small portable toy use case (which is my use case). I am weighing this against ST's STSPIN233, which is specifically designed for low-power use. It has an I_standby of 10nA, that's quite appealing, and low power consumption when running.

But then I need to pair it with 3x current sense amplifiers. And I'm having trouble understanding how to adequately design an amplification stage that works well for a small battery-powered portable setup. 

If I consider, for example, the INA181, I see that its power usage is quite a bit higher than that of the STSPIN, and indeed 3 of these far outweigh the consumption of the DRV8311. I'm still learning how to weigh all these factors, and maybe my thinking is wrong here. But if I'm right, it seems a little silly to pair that low-power driver with 3x INA181s (and the INA303 has even higher power requirements). 

But my confidence is low that I'm "good at this" at this point, which is why I came to ask what I might be missing. Are there current sense amplifiers ideally suited for small, portable battery-powered devices that you would recommend I check out? Am I fussing over the wrong thing here? 

Hello, 

Thank you for the follow up.

For our lower power devices, they will typically not have an integrated comparator and I am providing you with a link to these lower power options: Analog current-sense amplifiers product selection | TI.com

I understand that you are coming from a perspective where you want to preserve the most power as possible. 

I would suggest that you establish your system requirements including battery capacity. 

The easiest way that we can help you on this forum is if you compartmentalize your questions to focus on a specific product. 

For example, I would post a question only linking the https://www.ti.com/lit/ug/tiducy7/tiducy7.pdf in your post to ask any questions on the system. 

Once you have your required modifications to the system understood and you have your system requirements for your battery powered system, it will simplify your questions for the DRVs and INAs. 

This will help me with your INA3xx related questions and I can help you find the correct device once you have your requirements. 

I hope you understand and best regards, 

Joe

Ok, thanks.

I understand I'm asking several things at once. I think I was hoping to find some help navigating part searching, as I'm relatively new to this and, candidly, the video series about current sensing is a little overwhelmingly complex to someone who's never done it before. I'm grateful that it exists...I think I need to, I don't know, watch it a few times and see if I can wrap my head around the many constraints/facets I'm meant to be thinking about. For someone who isn't an expert on current sense amplifiers, it's quite dense. 

Thank you for your help. 

Hi again;

I am struggling to understand how to calculate (or estimate) the settling time of an op-amp or sense amplifier. I am curious if TI has any resources that steps through this process? I think I understand it to be affected by slew rate and bandwidth, and it's dependent on the step size seen at the input of the amplifier. But I'd love to see an explicit example to understand how to carry out these calculations (ultimately I am interested in understanding what my sampling time budget is, and how this relates to my PWM frequency).

Hello, 

Thank you for the follow-up. 

I believe there is a lot of great information in this TI precision labs series for op-amps: Precision labs series: Op amps | TI.com

Have you already taken a look at these videos and quizzes?

I hope this helps, 

Joe

Thanks so much!

(I realize this is secondary to this thread, but: could I please request that the "closed caption" button on the player for these videos be fixed? That button currently does not actually disable the captions - instead, it pops the video into/out of the browser window, which seems like a bug. The closed captioning is often overlaid directly over text or equations that are useful to be able to see, but can't because of the caption text being laid over top, and there's currently no way I can see to disable this.).