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Precision ADCs: December 2019 Update
My name's Bryan Lizon. I'm one of the product marketing engineers for the Precision ADC team at Texas Instruments. Today, we're going to talk about a couple of different things. This slide is just showing a brief introduction to the types of products that we cover. So on the left there, what we do, we do all of the SAR and delta-sigma ADCs at Texas Instruments, anything up to 10 megasamples per second. We have a separate team that does anything beyond that-- a high-speed data converter team. Precision ADC also supports the isolated amplifiers and isolated delta-sigma modulators as well as the audio ADCs and the audio codecs. Within all of those three product groups, we have automotive Q100 qualified parts. So we focus heavily on industrial and automotive products. And we have a large product family-- a large product group as you can see. So we're not going to talk about all of those products today. We're going to talk about a subset of those. But the first thing we're going to do is on the right-hand side. We're going to cover some important collateral. Our ADCs can be complex. They have a lot of parts, a lot of features integrated. So it often helps to have additional collateral to support some of those different features and kind of how to use our products. So we'll go through some fundamental knowledge that's not really specific to an ADC but maybe to a type of application or something like that. And then we'll have device-specific collateral as well that's related to a specific product group or product family. We'll talk very quickly about how to find ADCs on TI.com. And then we'll go over some hero products-- as it says on the bottom there-- within the factory automation space, our grid infrastructure products, and some general purpose ADCs. And we'll go through what that means as we get to those slides. With that, let's start talking about collateral. So the first thing we're going to talk about is what we call a kind of fundamental knowledge. This is in relationship to the types of collateral that we'll talk about. It'll be, again, less device-specific and more technologies and overall ADC type of information. So this can be introductory. But there's a lot of really important information, really deep technical knowledge that can help almost any engineer through his or her designs. So the first piece is Precision Labs. So this is not something that's specific to analog or-- excuse me-- to ADCs. As you can see the table of contents here, we have Precision Labs content for ADCs, amplifiers, for isolated products, for motor drivers, for interface, multiplexers, and sensors. So we have seven product groups that have Precision Lab material. What Precision Labs is is basically a comprehensive online classroom starting from the very basics. This image here is showing the SAR ADC input types. So what's the different between a single-ended input? What's the difference between pseudo-differential? Just going through some of that information. So that's where it starts. But then, obviously, it moves on from there to things like, how do you drive a SAR? How do you drive the reference inputs on a SAR ADC? And same thing for the amplifiers. For example, what is stability? Understanding stability, understanding slew rate, understanding offset and how all of those things interact with your device and with your system. And the great thing about this is that it ties fundamental knowledge to practical applications. So it's not just reading out of a textbook. It's taking that information and applying it to situations that our customers find that we find what-- as we're designing and developing products. So things that you can actually use in your day-to-day life. And last thing is for Precision Labs is they actually do have a hands-on training. So that's an additional feature. It's not something you need to do. But it has-- we have this board. You can see on the bottom right the image of this board. So this is specific to the ADC-- the ADC modules. And this is, again, gives you a hands-on, practical application of the theoretical knowledge you learn in the Precision Labs-- in the Precision Labs modules. So very powerful tool to use. This is something we constantly update. There's 180 videos across all of these different product groups. And we constantly add more. So this is just a really great place to start in terms of just a repository of all of the accumulated knowledge at TI. We also have these circuit cookbooks. So this is maybe an extension of the Precision Labs knowledge. So now once you understand the fundamental how our parts work, all of the different design and elements that you need to understand, this is basically saying, OK, now we'll take that information, and we'll apply it to a circuit-- common circuits that you'd find in everyday applications-- single-ended to differential level shifting, things like that. The example here is just showing how to do a high-side 3-wire RTD measurement. What the external circuitry looks like. How it goes into the ADC. How many channels you might need. What features inside the device you might actually need to use and so on and so forth. And these are, again, just basic circuits. And you can take these and modify them to your specific application. So again, if you want to choose-- you like the single ended to differential conversion application example, but you want to choose a different ADC, or, excuse me, a different amplifier. You can do that. And you can apply it to whatever challenge you're facing in your designs. And so far, as it says, we have 64 of these individual circuits for amplifiers-- 34 for ADCs and 15 for DACs, so approximately 115, 120 and counting. Again, this is something we're constantly adding new content to. So a great place to come back to and see if the thing that you're working on that day, it might actually be covered in what we're talking about. So it's just a great place to start. We also have the Analog Engineer's Pocket Reference. So the front cover is shown there on the bottom left. This is actually available in a hard copy, so a physical book. So for those of you who still like to hold things in your hands and actually flip through pages, that still exists. It's something you can buy on the TI store. Sometimes we give them out when we do customer visits and things like that. And it's a really good reference for just a lot of general information that's applicable to just circuit design. So, again, the example showed here is just resistor coding. You know how forgot how to read a resistor? This is a quick reference to show you, OK, this is what all the stripes mean and, again, how to read that. Or looking at the example on the right, settling time and accuracy, how it takes an RC filter to settle? How many time constants does it take to get to how many bits? Not something you might always keep in your mind. So it's, again, just a great reference to just be able to flip to and, OK, this information is available in this book. And you can flip to it easily. Right now, it's about 160 pages. So there's a lot of information there in there-- amplifier types, how to go from binary to hexadecimal, and everything like that. So just a lot a lot of information, very useful. And we also have it available, instead of the hardcopy, we do have a PDF version. You can just go to the TI.com and download. And there's also a smartphone app. So that's available at your-- whichever app store you use. An extension of that is this, the Analog Engineer's Calculator. That takes a lot of the information that's in the pocket reference and basically gives you-- acts as an extension of that to calculate a lot of those different aspects of what you see in the pocket reference. So for example, the image you're seeing here is-- if you look at this, this image is taken from the datasheet, the specific code you see here. So this tells you if you look at this, you add-- you fill in this information, the number of standard deviations, your peak-to-peak. This will tell you your noise-free resolution. This will tell you your effective number of bits. You can do this with-- if you took a measurement, for example. And so if you were actually doing your own measurements, you could just put this information in. You measure what are the standard deviation of your code distribution? Was is the peak-to-peak code? And that will tell you this information. And obviously, you can see on the left, there's a lot of different individual calculators, I guess, within this overall-- this overall piece of software. This is a downloadable tool. It's not something that you can use on TI.com, like WEBENCH, if you're familiar with that. This is something you have to download as an off-line tool, LabView based. Obviously, it has a lot of different tools to use within this. So, again, another really powerful piece of collateral to help you understand-- understand what our ADCs are doing and how to help you design them. So that covers the fundamental non-device specific collateral. And now, we're obviously going to move into the device specific where we're talking about maybe a single ADC or a family of ADCs that this piece of collateral is specific to. So the E2E forum, if you're not aware of it, it's basically an online community where you can go and post your questions, any question you have about a specific product. And one of our applications engineers will answer that question for you. So again, some of these examples you can see here asking about the external reference voltage on the ADS1248, register write and reading issue. Obviously, you can go in there and check out what those actually were. So you can post information here for sure. And we'll reply and have a back-and-forth with you to help you resolve your issue. But you can also search this-- search this as almost like a database of information to see if you're experiencing an issue with one of your devices. Chances are someone else might have already experienced that. And we might have already solved that issue. So another great resource to come and visit this, not necessarily to ask questions but to find just a huge volume of information on a part-specific basis. On the right-hand side of this image, these are Frequent Questions. So we have FAQs. This is something that, again, we internal post a question that we see a lot and then provide an answer for that. So we constantly update that as well. It continues to grow. We do that for a lot of our different product families. So you can see, for example, if you're looking for additional training videos for ECG, if you wanted to understand what that application is and how it applies to our devices, you can go to that specific FAQ. And we'll give you a bunch of links to collateral related to ECG applications. And again, constantly being updated. So something really powerful and important for you guys to check out. We also do these device calculators. Our data sheets, we have a lot of information in our data sheets. Sometimes it's more useful to provide a way to understand some of that information in a different format. So these are Excel-based calculator tools. So if you're looking-- for example, this is showing an ADS125H02, a part I'll actually talk about later. But if you look at the data sheet, the common mode range, there's an equation in there for common mode range. And it's dependent on, obviously, your input signal and the gain you're using, the supplies you're using. So that information can be a challenge to visualize what that response is going to look like. So this tool actually takes that information and allows you to visualize, OK if this is my input signal, this is what the common mode range needs to be based off of my settings. And you can play around with that. So again, it's interactive. Same thing with the digital filter response here shown on the bottom right. We provide a few plots in the datasheet or filter responses. But if you wanted something more specific, you can-- that tool's configurable. You can select any setting, any filter type, any data rate. You can put in whenever clock you want-- obviously within the datasheet parameters-- and it'll spit out what the digital filter frequency response will look like. And obviously, this is also highlighting the normal mode range, so that 50, 60 hertz reduction if you're interested in that, it highlights that as well. And it also shows the cutoff of the sync filter. So again, just interactive tools, just an extension of the datasheet-- the information that's found in the data sheet. And it really just helps reduce those design challenges and reduces your time to market as well. Last thing we have here is the software code examples. So this is something that we get commonly asked about. Hey, can you help me just get this part up and running? So this is usually just basic code. The code I'm showing here on the right is just a register read for this specific part, the ADS125H02. We do this for a lot of our newer parts. We do try to do some for our older parts. But the vast majority of our new devices releasing a piece in the ADC space, it will have this just generic code that you can build off of. You can use it and build off of to do whatever else you need to do. But again, just to help you get up and running quicker. And the next step is to do Linux-- code for Linux and for FPGAs as well since this generally uses-- this is generally for our MSP430-type microcontrollers. And one last thing I wanted to say about the collateral is-- and this is relationship to the circuit cookbooks-- there's a lot of information on this slide. But if you look on the left, I mean, this is just showing an example of a circuit cookbook. And what I want to highlight here is that specific piece of collateral, the cookbook, has a lot of ties into the rest of the information that we have on TI.com, a lot of things that are related to that specific-- that specific piece of collateral. So if there's any relevant Precision Labs modules or calculators or any other related content or code, all of that will be linked in this document. And then if there's any applications and equipment that we think is applicable to this cookbook circuit, we'll link there. Obviously, we recommend in these cookbooks, we'll have links to those as well. There's also a prefiltered search. So for example, this image shown here about the PT100 measurement, RTD measurement, we'll talk about a specific part. This one's using the ADS1261. But there's lots of other parts that can be applicable to this. So prefiltered search just gives you a list of parts that are applicable to that specific cookbook circuit so you can decide, OK, maybe I don't need something as fast. I might want a little bit lower cost. I need maybe smaller size or lower power or something like that. Then that gives you the freedom to choose which of these-- which part fits best for that specific application. So just reiterating the fact that this is a great place to start in terms of understanding all of the content that we have that's related to a specific application because in many cases, like I said, you want to come in and do a PT100 measurement. This just gives you everything you really need from start to finish to understand what that application is and how it applies to our products. So that's everything I've got for collateral. Again, there's a lot of information there. Most of the links are embedded in that presentation. But if you want more information, you can always type in-- type those links into your browser. Or you can reach out to your field team for more information. So the next thing I just want to show you real quick, how to find precision ADCs. Very simple. We have a parametric search on our product folder-- or, excuse me-- on our website. It looks like this. This green-- top green image here is the Quick Search. So those are the top used parameters that we have. So resolution, channel count, sample rate, that'll get you to usually pare down a lot to a much smaller number of ADCs. But if you just want to-- if you just have a few parameters and you want to do it real quick, there you go. On the left, on the blue are the whole list of parameters that we have. So once you narrow down a few, you get to maybe 20 products, those additional parameters there will help you narrow it down to the exact maybe-- or maybe two to three products. And then you can compare pricing and things like that from there. And the bottom red is just showing this is what the parametric search looks like. We have 558 products as of today. So a lot of information to sort. That's really the value of the green quick search and the blue full parametric search information. So just again, this is where you go to find our products. And we spent a lot of time trying to make sure that this is clean and up-to-date and the information is all accurate. So generally, it's absolutely the best place to come to find an ADC. So now let's switch over to some of the products that we have. And I think as I mentioned in the opening slide, we'll talk about three things-- the factory animation products that are generally the low noise 24-bit delta-sigmas, grid infrastructures. So these, again, are 24-bit delta-sigmas. We also have 12 to 18-bit SAR. These are specifically simultaneous sampling. And then we have some general purpose ADCs, SAR and delta-sigma. They're generally low power, small size, and low cost. So we'll talk about those three different types of product groups and a couple of products within each. So for factory automation, first product I want to show you is the ADS124S06/S08. These products are identical. The only difference is one has six channels, the S06. And one has 12, the S08. As you can see, this part has a lot of additional features built around it. It has the ADC. The delta-sigma modulator, and the filter, and the interface make up a really small footprint within this image. So everything else around it is to kind of help you reduce the size of your signal chain, lower your cost, and make your design easier. So this device has an integrated PGA, very low noise, down to 19 nanovolt. It can go up to about 4 kilosamples per second. And it's offered in a 5 by 5 millimeter QFN. It has a really, really good reference, low drift, 10 ppm per degree C max over the entire temp range shown here. Within a narrow temp range, that drift spec actually comes down. So it's on par with some of our ref 50/50, 50/25 discrete references in terms of the drift performance. And we also have a lot of these monitoring and diagnostic features built in. So one of these shown here is the PGA rail detection. So if your input signal gets too close, once it gets through the mux, goes into the PGA. The PGA is a true high-impedance instrumentation amplifier. So it has some common mode range. You can't get too close to the rails. So if you start getting into that nonlinear region of the amplifier, you want to know that. Your ADC will still convert that. But you won't know that you're in that region. So there's flags for high and low on both the positive and negative input to the PGA. So just another thing to understand the health of your system. We have a reference detect feature. So if your reference-- if were you're using an external reference or a radiometric reference doing an RTD or something like that and your reference became disconnected, you won't necessarily know that. Again, your ADC will still continue to convert because it does not know that your reference voltage has dropped to-- it has been disconnected. So that feature actually is a detection feature to determine if it drops below a certain threshold that you are able to actually detect that. So again, just features built in to help you understand the health of your system-- the ADC itself, but the system around it too-- and make your systems a little bit more reliable. So again, that's for the ADS124S. You also have the ADS1260. So again, you can see that the block diagram looks very similar. The main difference between this device and the previous one is this one only has five or 10 channels. It can sample faster, up to about 40, so about 10 times faster, 40 kilosamples per second. The noise is about one third. So the previous device was about 19 nanovolt. This one's down to 6. So you get you lower noise performance. And the difference here is-- the last difference here is power. So this device will consume about 10 times more power compared to the previous one. So these are just kind of-- if you needed the lowest noise, you might use the ADS126. If you need the lowest power, you might need the ADS124S. The feature set is very similar between the two parts. So just a trade-off between those power and noise and speed. So just two different product offerings for a lot of the same types of applications. We also just released this part. This is the ADS125H. Looks similar to the parts I just showed. The main difference here is this can actually take a plus or minus 15 volt input directly in terms of absolute input voltage. So this device has a true high voltage, high input impedance PGA. It does require high-voltage supply to work, like a PGA 280 if you're familiar with that part. It has a lot of the same features as the previous parts I showed-- the current sources, integrated reference, and GPIO pins if you want to control the mux. All a lot of the detection features are there as well. Again, the main difference here is if you wanted to do an analog input measurement, so plus or minus 10 volt, you can do that directly with this device instead of needing a resistor divider or some sort of attenuation stage that you would need with the previous devices. This device also has the PGA built in and do attenuation and gain. So if you want to measure both 10 volt and thermocouple 420, 40 millivolt input, you can do all of that with the same device. So now I'm going to switch over to the grid parts. So these are for applications where you need to do sampling measurements, whether that's three-phase voltage, three-phase current, protection relays and electricity meters, things like that. So this is a SAR product. So this is the ADS858 family. And we have 14, 16, 18-bit versions and different sample rates. So can see that table here in the middle. This device can do-- can accept plus or minus 10 volts on a single fivefold supply. So this has a differential amplifier input structure. So it has one megaohm input impedance. And these are single ended inputs. But again, you can see there's simultaneous sampling. So you do actually have-- there's deterministic phase delay between channels and things like that. So you can actually sample multiple inputs at the same time. So that's obviously really important for electricity phase measurements in electrical systems. We also have the ADS131A02. So this is a 24-bit delta-sigma. Same thing, simultaneous sampling. This is a 5 volt only ADC. You would need an attenuation stage if you wanted to do something higher than that. But this is if you want just a generic high speed delta-sigma ADC that's simultaneous sampling at a good cost point, this is one of the devices you should choose. Again, 24-bit performance, 128 kilosamples per channel or per ADC. So you don't get that-- you don't get that kind of conversion slow down with a muxed-ADC. So you can just constantly sample each input at up to 128 kilosamples per second. So again, another really good device, 5 by 5 millimeter package. So small, up to four ADCs in one device. We also have a next-generation version of that. This is looking at having some of the features specific from metrology, so energy metering. This is the ADS131M series. So you can see, it looks very similar to the previous part. The main difference here is that it actually has gain included, the amplifier in the front. So gains from 1 to 128, all the binary gains. So this is good, again, for doing those voltage and current measurements. But at the same time, this can be used for a lot of different applications if you just need a high speed or higher speed simultaneous sampling delta-sigma. So this part, the 131M04 just released this year. And the follow-on devices, the M02, to the M03, we'll start releasing-- within the next nine months, we'll release different package variants and different channel counts of all of these parts. So the 131M is the released part for now. And that's it for the grid parts. So now I just want to talk real quick about the general purpose ADCs. For us, general purpose is anything less than 16-bit. And a general purpose ADC is something you might need to measure a power rail or a current rail or a temperature or something like that with reasonable accuracy, reasonable precision. And you need-- obviously, in those cases, you need small size. You need low power. You need low cost. So this is just a generic introduction to those parts. So again, cost is usually king here for these types of parts. They're not your main signal chain ABC they're doing, again, some sort of monitoring function. So we do have parts that are very inexpensive. Just like on TI.com, you go to there. This is the pricing you'd see. We also have really small devices. So you can see here that we'll be releasing a part soon that's 4 channel, 16-bit delta-sigma whose total area is 1.3 square millimeters. And obviously, that leads to high channel density in terms of how many channels we have per square millimeter. You can see all the different offerings we have in terms of how many channels and the size for each. And then these do have some features as well. So they'll have things like GP1O pins or integrated PGA or reference. So it's not just a bare-bones ADC. You do get some extra add-ons even with the low cost and the small size. So an example of one of these parts is this family we're releasing by the end of this year. So this is the ADS7128/38. And there's a TLA version which is like a lowest cost device. So this is just an 8 channel SAR, 12-bit SAR. You can have-- there's an averaging mode. So if you want to go up to 16-bit, you can do that. It does have a channel sequencer, so it helps reduce your communication overhead because you can just program whichever channels you want, and I'll constantly loop through those channels and convert them. The 713 and a comparator, and a high and low threshold and a CRC on the outgoing-- on the communication lines. So the comparator is just good because you can sample your input. And you can just let your-- you can just constantly let the device run. And then when-- if you hit one of those thresholds high or low, you can send an alert to your microcontroller. You can wake it up. Or you can just-- you can just tell your microcontroller, hey. Something happened that you need to check out. But you don't need to constantly be looking at that data. So we call that autonomous monitoring as shown here. And then the last one is the 7128 which includes a true RMS and a zero crossing detection module. All these devices are pin compatible. So again, they'll all be releasing by the end of this year. And then obviously, these are some of just the applications we have. The voltage supervisor with, again, that fast alert, I mentioned the alert in zero crossing detection for appliance. So it just rejects that transient spike when you cross the zero point, obviously, on your input. Temperature control things like that. The RMS is built in, again, to the ADS7128. So you can do that if you need the root mean square measurements. And also the inputs are also useful GPIO pins. So they sort serve dual purpose. So they can be analog input or GPIO. So you can think of it almost as an ADC channel or an I/O expander. So you can use the first four inputs as analog input. And you can use the other four inputs as GPIOs to control maybe external switches or muxes or something like that. So especially useful in isolated systems. So this is just an introduction to one family of parts within that general purpose portfolio. And we have about 150 parts. So if you need something, you want to do some sort of just generic monitoring, we have an ADC for you.
Description
December 2, 2019
An update on the latest precision ADC related tools, content and devices available from Texas Instruments.
PDFs for download
precision_adc_update.pdf
Additional information
Learn more about TI precision ADCs
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