The May 2104 interim meeting of the IEEE802.3bt task force was recently held in Norfolk, Virginia.  Over the course of three days, the task force heard approximately 20 presentations including ad hoc reports, technical contributions, and baseline text proposals.  All of the presentations can be found on the public website. 

One thing I am happy to report is that the task force has begun the process of building the new standard by adopting baseline text for the first time.  For those of you who are unfamiliar with the process, text for the new standard (or modification of the existing clause 33 text) is presented as baseline text in presentations given to the task force.  If a motion is called to adopt the text, it must be approved by 75% of the people in the room (counting only those who vote yes or no).  The editor then takes the baseline text and includes it in the working draft of the standard.

We adopted two baseline text proposals during the May interim.  The first set of baseline text approved addressed the need for lower standby power and set forth the maintain power signature (MPS) behavior for new PSEs and PDs.  The second collection of baseline text approved both modified the existing text and added new text to allow powering over 4 pairs.  Both sets of text were adopted with unanimous motions (full disclosure:  I was a coauthor on both baseline text proposals).  You can find the presentation with all the straw polls and motions taken in Norfolk here.

Another key development coming out of Norfolk is the formation of two new ad hoc committees.  The first new ad hoc will study the question of if we can power existing Type 1 and Type 2 PDs over 4 pairs.  The second new ad hoc will collect use cases for 4 pair power delivery so that we can consider them when crafting the new standard.  In addition, the two existing ad hocs, one dealing with pair-to-pair current unbalance and one dealing with cabling requirements for high power, were both reinstated for another cycle.

What do you think?  Are you as excited as I am that we have broken through and adopted our first baseline text?  What questions do you have after looking over the presentations given in Norfolk?  Ask in the comments below and I will do my best to answer them.

PoE resources:

• Read all IEEE blogs here

• PoE PD efficiency calculator tool

• PoE system block diagram

• PoE powered device (PD) products

• PoE power sourcing equipment (PSE) products

We’ve likely all seen situations where we’ve needed to sweep the frequency over time.  If you are faced with this, consider an application like radar where a transmitted signal is bounced off a target and compared to the received signal, as shown below in Figure 1.  If we look at the difference in frequency (Df), we can determine the time that the signal took to return (Dt). Once this time is known, we can then find the distance to the target.   If the slope of the line is made steeper, then the system is less sensitive to noise, but this comes at the expense of reducing the range.

Figure 1: Frequency chirp waveform

For radar applications, it is important that the waveform produced in Figure 1 is very linear and has a constant slope in order to avoid frequency miscalculation.  In applications where more nonlinearity can be tolerated, use a digital to analog converter (DAC) to steer the control voltage of a voltage controlled oscillator (VCO) in order to generate the desired waveform. One challenge with this open loop approach is that the slope of the waveform is impacted by part-to-part variations, temperature, VCO frequency drift and VCO frequency supply pushing.

For applications demanding better linearity, an alternative method is a Phased Locked Loop (PLL), like the LMX2492, to create the waveform by adding fractional modulation in the feedback divider.   Figure 2 below shows an actual measurement that emphasizes one of the challenges for a 45us frequency chirp from 9850 to 9400 MHz.   The abrupt frequency change causes overshoot and cycle slipping, but this is reduced by programming the device to 9800 MHz and staying there for 5us and then continuing the ramp.  By using this two ramp approach, as shown in Figure 2, performance is improved.

Figure 2: Measured frequency chirp with the LMX2492

Aside from using additional frequency ramps to improve the linearity of the waveform, they can also be used to create more complicated waveforms.  For instance, a dual ramp approach, as shown below in figure 3, can be used to account for the Dopper shift for a moving target.

Figure 2: Dual ramp approach

The examples I’ve shown are fairly basic, but you can create much more complicated waveforms using more linear segments, or to introduce more ramps.

In our ongoing series, ‘One to Watch,’ we profile the movers and shakers at TI who are making a difference through their extraordinary work.

Some people just know they are going to be engineers. They were tinkerers growing up, always taking apart and rebuilding electronics and constantly fascinated by how stuff works. Nicole Navinsky is not one of those people.

Nicole was set on being a doctor because of her passion for chemistry and strong abilities in math and science. But like any good parent, her mother started doing some research about how students who excel in math and science could turn these talents into successful careers. Nicole’s mom encouraged her to look into engineering.

“I actually didn’t have any exposure to engineering as a child until my mom did her research,” said Nicole, who today is an applications engineer for DLP front projection. “But once I found a degree at Southern Methodist University (SMU) that offered pre-med and engineering together I decided to give it a try.”

And Nicole never looked back. Over the course of the last six years, Nicole’s focus has been squarely on engineering both in the classroom and in her extracurricular activities with the Society of Women Engineers (SWE). At SMU, she worked her way up the SWE leadership chain as vice president, then president, and eventually the region conference chair while also racking up awards including the SWE Future Leader in 2010, SWE Goldman Sachs scholarship in 2011 and the SWE Region C Collegiate Emerging Leader Award in 2013. After she graduated in May 2013 with her Masters in Electrical Engineering, she added one more award to her resume – the SWE Outstanding Collegiate Member Award. Not bad for someone who just a few years earlier didn’t really know what engineering was all about.

“I realized I’ve thought like an engineer my entire life, especially when it comes to problem solving. The field has so many opportunities,” she said.

While at SMU, Nicole interned at TI as a product/test intern for High Speed Products in Analog Engineering Operations, carrying out high temperature tests on existing products to determine whether the products had good reliability at high temperatures. While she loved her co-workers and TI’s culture, she wanted to use the skills she learned as a leader with SWE in her everyday job. As Nicole reached her graduation date, she talked to TI about moving into a customer facing applications position where she could help people with their technical issues. A position was available in the DLP Front Project group, and she jumped at the opportunity.

“DLP is a cutting edge technology that can be used for more things than just projection,” said Nicole. “I love that TI gave me the opportunity to change roles after my internship. It showed they cared and wanted me to find the right fit.”

Today, Nicole works with customers in Taiwan and Japan, directly answering their technical questions while also developing application software to help customers integrate software and hardware into their products. She also has started traveling to Asia, a first for her. While the international travel is an exciting perk of the job, the opportunity for Nicole to be the best engineer she can be is why she’s happy to work for TI.

“TI is always looking for new markets and new places to grow the business. And with DLP, we’re always working on breakthrough innovations. You realize that innovation can come from anyone, anywhere, at any time,” said Nicole. “TI encourages that we make suggestions and not be afraid to ask questions.”

It is because Nicole’s mom wasn’t afraid to ask questions that she got to where she is today. At TI, we’re grateful for mothers like that!

As our communications processors team gets ready to head to London again for the annual Small Cells World Summit, we’re excited about what we’re going to hear, who we’re going to meet with and whether we get to take home another award for our small cell technology!

This year, the Small Cell Forum received a record number of entries from around the world for their annual Small Cell Industry Awards, “further attesting to the relevance and growing traction of the small cell business case” in their words. We couldn’t agree more, which is why we are incredibly excited to be shortlisted for the best “small cell access point design and technology innovation (vendor)” award alongside two highly regarded companies, Cisco and Spidercloud. Still, we believe our TCI6630K2L small cell SoC gives them a run for their money – but we’ll see next Wednesday when the winners are announced!

As far as what we can expect to hear at the Summit this year, Wi-Fi integration should continue to be a popular topic and discussions around how operators will use it will be at the forefront of the dialogue. Similarly, while indoor small cell enterprise deployments are where a lot of the near term traction will be, the focus of the discussion should shift to how we ensure reliable quality and comprehensive service rather than just add more capacity.

Finally, we can also expect to hear a lot more about backhaul.  With yottabytes of data traversing our networks each month, industry experts are discussing how this data makes it from the local access point back to the Internet. Clearly it will require careful design, operational planning, capital investment and focused execution to build up the framework needed to support the enormous amounts of connection points out there. Since 70% of the base stations use a wireless link for backhaul to the Internet, it shouldn’t come as a surprise that operators are hyper-focused on finding cost effective solutions to build out the infrastructure. To wit, this year’s Small Cells Summit even features a backhaul track with sessions like,“Implementing today small cell networks with novel backhaul solutions” and, “Assessing advancements in technology to enable efficient backhaul” on the agenda. 

Are you planning on attending the Summit this year?  If so, we invite you to stop by our meeting room in London to chat with us or catch a live demonstration of our latest technology!

They say that if you are using your amplifier to drive a capacitive load (Figure 1, C_LOAD), a good rule of thumb is to isolate the amplifier from the capacitor with a 50 or 100 Ohm resistor (R_ISO). This additional resistor may stop your operational amplifier (op amp) from oscillating.

Figure 1. An amplifier with a capacitive load may require a resistor between the amplifier output and the load capacitor. 

The use of 50 or 100 Ohms (R_ISO) may not work every time. A key question to ask is, “What do I do if my C_LOAD exceeds the recommended data sheet op amp capacitive load value?”

If you can’t find any data sheet guidance or your load capacitance (C_LOAD) does exceed data sheet recommendations, the answer to this question depends on the:

• amplifier gain bandwidth product (GBWP or f_U)
• amplifier’s open-loop output resistance (R_O)
• capacitor load value (C_LOAD)

The frequency versus gain graph in Figure 1 shows what happens to the amplifier’s open loop gain curve when an R_ISO and C_LOAD are added at the output of your amplifier. If you use these three variables, you will find the appropriate R_ISO value.

Here are rules when determining the value of R_ISO:

                         (Eq. 1)

                (Eq. 2)

These rules ensure that the circuit is stable.

An appropriate application to apply this concept is where you are driving the input to a SAR-ADC. In this case, you want the signal to settle within the acquisition time (t_ACQ) of the converter. In Equation 3, K is an ADC time-constant multiplier that provides half-LSB accuracy. For a 16-bit converter, such as the ADS7886, K equals 11.78.

            (Eq. 3)

Let’s put these formulas to use. Working with the following parameters:

• With the OPA365

• f_U = 50 MHz
• R₀ = 30 ohms
• Gain = 1 V/V

• With the ADS7886

• t_ACQ = 300 nsec
• C_IN = 21 pF

• C_LOAD = 390 pF

According to the OPA365 data sheet, a load of 100 pF will product an overshoot of 30% (Figure 2).

Figure 2. OPA365 Overshoot versus capacitive load

To solve this overshoot problem, equations 1, 2, and 3 can help.

• With equation 1, R_ISO =>   3.33 Ohms
• With equation 2, R_ISO => 30.97 Ohms
• With equation 3, R_ISO ~  61.96 Ohms

Given these three equations, R_ISO must be equal to 61.9 Ohms (0.1% tolerance).

Some manufacturers include a stability versus capacitive load typical performance curve in their data sheet. They may even provide a line in the electrical performance table. All this information is very helpful, of course. However, you can avoid amplifier oscillations or excessive overshoot with the calculations used in this post.

References

• For more information, download these datasheet: OPA365, ADS7886
• Baker, Bonnie, “Start with the right op amp when driving SAR ADCs,” EDN, October 16, 2008
• Baker, Bonnie, “Charge your SAR-converter inputs,” EDN, May 11, 2006

It is almost always necessary to measure some sort of current.  In my last post, I covered two main reasons why you should measure current and a few ways to do so using loss current sense techniques. This post will focus on loss-less current sense techniques.

Use what you already have! We are going to talk about two ways to sense current using circuit elements that are already present.  Those two methods are inductor DCR sensing and FET sensing.

Inductor DCR sensing is not super accurate, but good enough.  Typically, the DCR of an inductor is on the order of +/- 10%. Factor in temperature changes to the copper and you can get some pretty inaccurate measurements.  One saving grace is that after the DCR network, you end up with a pretty clean signal that does not have switching noise.  Figure 1 shows the network necessary to extract the current information from the DCR of the inductor.

Figure 1

The components of this network are chosen by the equation below:

There are a couple of factors that need to be taken into account when setting up the DCR network:

1. Maximum signal size that the controller or sensing circuit can handle - it may need to be divided down.
2. Temperature compensation - components with a negative temperature coefficient can be used to help keep the DCR constant over temperature.

Usually, DCR sensing is used in a multiphase configuration for current-mode control.  It is very easy to implement current sharing between multiple phases using this technique.

Use FET sensing, but watch out for switching noise!  When FETs switch, a lot of noise can be generated.  This noise needs to be filtered.  Figure 2 shows a FET sensing scheme and how noise can interfere with the measurement.  A couple of things can be done to mitigate this noise, but they do not come without penalty.

Figure 2

1. Filter using an RC network.  This is okay, but it can round off the current signal and the edges are not clean.  The rounded off current sense signal can lead to jitter and other noise issues.
2. Leading edge blanking.  This is a technique where the first part of the current sense signal is ignored.  The main issue with this is it leads to a minimum on-time, if there is an issue the duty cycle can only be reduced so much.

Figure 3 shows the penalty from the two fixes shown above.

Figure 3

Loss-less current sense techniques are not as accurate as using a precision resistor, but avoid the efficiency and power loss issues.  Usually the loss-less methods are good enough for the application that the efficiency gains outweigh the accuracy issues.  The methods for current sensing covered in the last two blogs are by no means the only ways.  Leave a comment and let me know how you do it!

Related resources:

• Read: All PowerLab Notes
• Easily find and use one of nearly 1500 reference designs: PowerLab Reference design library
• Find: Power Management products

Establishing a smart grid is critical for the future of our energy supplies. Grid inefficiencies, aging infrastructure, and damaged systems across the globe are causing us to lose energy.

TI created a Smart Grid and Energy solutions team to help solve these problems; our experts develop and refine measurement and communication technologies to ensure every person in the world is serviced by a reliable grid.

The world is moving from centralized to distributed energy sources and TI technology is supporting that change with semiconductor solutions that give developers the widest range of scalability and performance options available, along with advanced tools, software and support to develop smart grid designs faster.

More and more energy system designers are counting on TI to make their equipment even smarter, with integrated sensing, processing, and communication functions that are innovative and future-proof.

Our technology plays a key role in power substation automation, which delivers advanced monitoring and protection capabilities. This saves time and energy by remotely monitoring and operating substation equipment, and allows for quick responses to shifting power demands. With low-power radio frequencies (LPRF) and power line communication (PLC) technology, utilities can greatly improve energy management from generation to distribution – all the way to the smart meter. This makes it easier to add large-scale renewable energy sources to the power mix.

To improve energy conservation, TI is delivering full system solutions to communicate, measure and manage the energy in smart grid systems, letting people and communities manage their own energy needs. TI’s communication technology also allows homes and businesses to connect with their utilities through smart meters and networking protocols so they can monitor and manage energy usage in real time.

Learn more about our vision for the future of the smart grid and smart cities:

Texas Instruments has today’s semiconductor solutions for tomorrow’s energy systems, from grid infrastructure, to better smart meters, to enabling new energy services for the end user, and connecting systems with future-proof communication platforms. Learn more about TI’s smart grid solutions: www.ti.com/smartgrid.

Discover TI’s vision for the smart grid and energy markets in this new industrial video and read our new white paper about technologies that will allow smart cities on the grid to embrace renewable forms of energy generation.

 Learn more about TI’s smart grid capabilities in these blog posts featured during #OntheGrid week:

• Engineering a smarter energy grid– On the Grid

The ultra-low-power C5517 DSP is now available and ready to make a big splash in the power-hungry audio and vision applications. 

The C5517 is ideal for analytic applications – such as wearable technology, because it is capable of extracting motion information, visual motion tracking and more. Wearable technology brings smart, dynamic processing to static mediums to improve interaction with the world.

This technological revolution comes with a number of challenges that must be addressed before productizing the innovation, such as size constraint, power consumption and performance.  To improve power consumption and meet the mathematical and real-time requirements designers can turn to DSP architecture. To achieve long battery cycles, the architecture must focus on efficiently balancing performance and power consumption.  While DSP architecture can vary in size, the low-power variants focus on highly efficient performance during operation reducing the power consumption of the algorithms used to extract useful information.

Power consumption is important in wearable technology because it allows customers to not worry about the battery operation for several days, weeks or months. Ultra-low power consumption also enables cool device operation in tight in enclosures.  No one likes an overheating wearable! Cool technology must come with cool esthetics, and DSPs are a perfect processor due to their small size with large processing capabilities.

 Can you think of any other reasons why a DSP is ideal for wearable technology?

You can find the original blog post on this topic here. 

      Additional resources:

• Fuel your power-hungry audio and video applications with a DSP of your own!
• Listen to a TI expert explain how the C5517 reduces the footprint for analytic applications.
• Learn to create low-power vision applications with the C5517 in this video. 

 It’s great to be a little brother. I’m speaking a bit out of turn on this, as I am an older brother that carries a bias, but I definitely think younger siblings have it made.

A few of my observations on the characteristics of younger brothers:

-          Older brothers bravely forge a path helping to define boundaries and convey lesson-learning (generously assisted and guided by their parents), as well as allow younger brothers to greatly benefit from their investments (clothes, toys).

-          Younger brothers also bring something new and different to the table – they strive to carve their own unique skill sets that often balance both a competitive and easy-going nature. They are also fiercely loyal to their families.

-          Finally, and this I know to be true, little brothers are spoiled.

As I think about TI’s newly announced “Jacinto 6 Eco” infotainment processor, I can’t help but be drawn to the similarities of this device as the “little brother” to the “Jacinto 6” device first announced at CES in 2013:

Path-forging:

-          “Jacinto 6 Eco” offers software and pin-compatibility with “Jacinto 6” family of devices as a result of being a direct subset of the “Jacinto 6.” Manufacturers designing infotainment systems can develop products for a broad range of vehicles from entry- to mid-level, all the way to luxury on the same platform, leveraging investments across products, ultimately reducing costs and time to market.

Lesson-learning:

-          “Jacinto 6 Eco” offers the ability to bring class-leading functionality and use-cases from the last-generation premium platforms to the current-generation entry- to mid-level platforms. Consumers are now demanding increasingly responsive user interfaces with large displays and low-latency speech interaction.  These features are now more available than ever through “Jacinto 6 Eco’s” cost-effective performance and BOM integration. The BOM integration opportunities include integration of vehicle interfaces (without auxiliary Cortex M4 cores together with CAN, MOST Media Local Bus (MLB), Ethernet AVB), software-defined radio integration (AM/FM/RDS, HD Radio™, DAB, and DRM) and advanced audio post-processing capabilities on the C66x DSP, both of which can reduce the need for additional components or cost in other parts of the system.

Unique:

-          I most closely align this characteristic with the scalability that “Jacinto 6 Eco” offers to the “Jacinto 6” family. Both “Jacinto 6” and “Jacinto 6 Eco” are built on the same architecture, offering software- and pin-to-pin-compatibility with the broadest array and highly scalable architecture of ARM® Cortex™-A15-based devices for automotive applications. Specifically, with “Jacinto 6 Eco” (single ARM Cortex A15, single Imagination Technologies' POWERVR™ SGX544, single 32-bit DDR2/3 interface) and “Jacinto 6” (dual-core ARM Cortex-A15, dual SGX544, dual 32-bit DDR2/3 interface) offer a CPU range of 2,800 to more than 10,000 Dhrystone Million Instruction Per Second (DMIPS).

Spoiled:

-          This might be a stretch… but “Jacinto 6 Eco” will enable a level of digital life integration for drivers through seamless integration with mobile devices while still providing a premium infotainment experience without the premium price tag. With the ability to “mirror” the capability and applications on your smartphone courtesy of TI’s IVA-HD video co-processor supporting 1080p high-definition video streaming, you can integrate your mobile office and latest capabilities of your phone with your car’s built-in capabilities. Talk about pampering.

Notice how I’ve avoided the middle child comparisons? I don’t think either of us could have handled those analogies! For more information on “Jacinto 6 Eco” and the “Jacinto 6” family of devices please be sure to look for more posts on Behind the Wheel.

In our ongoing ‘On the Fringe’ series, some of TI’s brightest minds discuss today’s biggest technological trends and solving the challenges of tomorrow.

When I tell people that I am the director of autonomous vehicles research and development (R&D) at TI Kilby Labs, the response I usually get is, ‘Like cars that drive themselves? Cool!’ And, yes, we are doing some amazing things here at TI to enable autonomous vehicles.

While we do focus a lot on driverless cars, trucks and SUVs, autonomous vehicles expand well beyond our roadways. We’re taking the same technology being developed for cars and putting it into all types of vehicles and robots. Our future will be much more autonomous than you can ever imagine.

For example, we already know the unmanned aerial vehicles (UAVs) market is huge, with UAVs being used in all sorts of applications, but making these vehicles not just unmanned, but autonomous, is the next step. Autonomous UAVs can be used in military applications, to distribute goods from online retailers, for video recording at sporting events, TV shows and movies or even as surveillance and security for businesses and homes. Imagine two quadcopters (a form of a UAV) where one sits on a battery charging station while the other flies around your property, monitoring for and focusing on moving objects. The quadcopter can identify a moving object (like a criminal) and quickly warn of an intruder. Once its battery runs low, the first quadcopter flies back to the battery charging station and the other quadcopter takes off without any human interaction.

On the medical front, researchers are experimenting with robots treating children with Autism or other developmental disorders. The robots must be able to autonomously sense the behavior of a child and respond or react accordingly. Use of robots exist today in hospitals, and I expect this trend to continue to grow, although I believe we are still a long way away from robots performing surgeries without human interaction as there are many dexterity issues that still must be resolved.

From construction sites to battlegrounds to farms, vehicles on four wheels are the backbone of these industries. But creating autonomous vehicles for building a skyscraper or to plow a field of cotton has many more complications to overcome than vehicles on the road. Roadways are very structured, from the material used to pave roads to lane markings on the road. Off the road, the environment is very unstructured, with no lanes to guide vehicles and issues such as whether the ground beneath the vehicle is hard or soft. Essentially, there are many more types of obstacles, so it will take us longer to create systems that can identify all of these challenges. But I believe these types of vehicles will become a reality in the future.

When it comes to autonomous robots in our homes, most do nothing more than clean our floors today – but I believe they can work smarter and better, with increased capabilities, than what we have available now. And why couldn’t an autonomous vehicle/robot fold or iron our clothes? Why can’t a robot load the dishwasher? There are near limitless applications inside the household for chores to be completed autonomously.

Autonomous robots exist to some degree in warehouses, but there is a great opportunity to create vehicles that have the capabilities to find and pull objects from a shelf in a massive warehouse and then package the objects for shipment.

The final area where I see autonomous vehicles is in an office setting. Telepresence vehicles exist today where with a joystick or controller a person can remotely move about an office with a fixed camera and monitor. But we hope these telepresence vehicles can one day autonomously find office rooms simply by saying into a microphone, for example, ‘Go find Daniel.’ The vehicle will know where Daniel’s office is, go to Daniel’s office door, knock, and open the door when Daniel gives the proper response (like, ‘Come in.’).

While the applications are nearly endless for autonomous vehicles, how do we go about making them a reality? Autonomous vehicles are a two-step process. First, these vehicles must be able to understand the world around them. Using cameras, radar, lidar and ultrasound, vehicles can get a very good 3D picture of objects near and far. The second step involves translating that data into something a computer can understand. This processing takes place in a microprocessor that can then tell the vehicle about its environment and how to respond, whether grabbing a particular item off a shelf, record the trespasser on your property or spend a little extra time getting the wrinkle out of a shirt while on the ironing board. Once a vehicle understands the environment around it, then it can focus on the task at hand.

This technology is available today, but at a great cost. My job is to make sure this technology continues to develop and improve so that one day it can become cost effective, and vehicles and robots all around us, in all shapes and sizes, will help run our world autonomously.

If you want to learn more about autonomous vehicles like cars and all the ones described above, read this white paper and watch the video below with my Kilby Labs colleague Kristen Parrish discussing all the ways we’re enabling the autonomous vehicles of the future. 

(Please visit the site to view this video)

With extensive smart meter deployments across the globe, the energy segment is going through an active transformation. Enablement of a smarter grid infrastructure facilitates a bi-directional flow of energy and data; however, it comes with added cost and complexity. The technical and economic challenge of every installed meter directly communicating with utility servers makes the solution unpractical. To optimize the compound network of these advanced systems, automation of the core components is essential.

Meters deployments can be broadly classified into two types of networks – Neighborhood Area Network (NAN) and Wide Area Network (WAN).  Both of these networks are enabled by using a diverse communication protocol. An automated metering infrastructure can be enabled through a data concentrator. These aggregators aid in data communication between meters and energy service providers.

Data concentrators are a critical node in this automated network, they securely aggregate data from a manageable number of meters and relay the information to the centralized utility servers. Meters record user electricity consumption at regular intervals and provide this data to the utility provider.

The frequency of this data feedback ranges from an hourly feedback meter to real-time meters with a built-in two-way communication structure. These systems could have the capability of recording and transmitting instantaneous information. The recorded data provides more information on the load of the various end points that are actively consuming energy.

Not only can this information be used by the utility providers for billing services, but this could also be leveraged to improve customer relationship through enhanced consumer services such as real-time energy analysis and communication of usage information. Additional benefits of fault detection and initial diagnosis can also be achieved, further optimizing the operational cost. What other benefits can you think of?

To learn more about how TI’s scalable Sitara processors are used to enable the core of energy and data management, read our data concentrator whitepaper.

Discover TI’s vision for the smart grid and energy markets in this new industrial video and read our new white paper about technologies that will allow smart cities on the grid to embrace renewable forms of energy generation.

Learn more about TI’s smart grid capabilities in these blog posts featured during #OntheGrid week:

• The power of information #onthegrid– Tools Insider
• Engineering a smarter energy grid – On the Grid

Many modern portable devices must be shipped with a battery installed so that a customer can power it up initially without any battery installation or charging. Any excessive current “leakage” from the components connected to the battery may result in a dead device in the hands of a customer.  All components are capable of leakage currents, and while IC’s are the primary culprits, capacitors, board contamination and humidity can have unpredictable levels of leakage.

Solving this problem is not trivial – the maximum shelf-life is achieved when the load is completely disconnected from the battery, however, any power-up detection circuit will need a battery connection to function.  PCB area is also critical in many battery-powered applications, making it is difficult to justify space for a single latching switch circuit. 

An easy, straightforward approach would be to disconnect the battery with a simple P-type MOSFET (PMOS) and N-type MOSFET (NMOS) latch.

However, this seemingly simple circuit can lead to unreliable performance.  Any glitch on the button will turn the latch on.  Additionally, the latch may turn itself on when the battery is inserted if the output voltage bounces positive or the capacitive divider created by the C_GS of the PMOS and the C_DS of the NMOS turns on the PMOS device.  Of course this could be fixed by adding some extra resistors and capacitors, quickly increasing the size and complexity of the design for a very basic function.

A better design is given below which avoids the glitches of the basic latch by enabling the load with a button push of 7.5 seconds, utilizing Texas Instrument’s TPS3420 push button controller to turn on the switch. 

The TPS3420 is an ultra-low Iq push button controller.  The TPS3420 has two push button inputs, only one of which is used in this solution.  When the button is pushed (any existing button on the system can be used), it connects one half of the dual Shottky diode to ground, which then pulls the PB1 input of the TPS3420 low.  After the PB1 input is held low for 7.5 seconds, the open-drain output pin RST of the TPS3420 will pull down on the gate of the PMOS switch, connecting the load to the battery.  The other half of the dual Shottky diode will provide a latching mechanism so that when the RST pin goes low, the PB1 pin also stays low, keeping the RST pin low until the battery is completely discharged or removed.  This solution uses the tiny CSD23381 (1 mm x 0.6 mm) PMOSFET as a disconnect switch from the battery to the load. 

At less than 1 µA of total current consumption when the system is off, this solution can extend the shelf life of any battery for very long periods of time, eliminating the risk of a disappointed customer finding out his/her new device already needs to be charged.

Give this solution a try and let me know your thoughts or questions in the comments below. Good luck!

When I was a kid, someone from the power company regularly came to our house to read our electric meter so that we could be billed for our home's power consumption. Not only was this time consuming, but it also meant sending people into remote areas, and I'm sure everyone has heard stories of technicians being chased by the family dog. But with the advent of the smart grid, manually reading meters is becoming a thing of the past.

Over the past few years, a revolution has been happening for the power grid. It is becoming “smart.” What does this mean? The primary purpose of the power grid is to transport power from a power plant to your house through electrical wires. Your house has an electrical meter that shows how much power you have used, and you get billed for it. Since your house is already connected by a network of wires to the power plant, why not use that connection to transfer information in addition to power? This is where the smart grid comes into place.

By using a noise-resilient modulation scheme (such as OFDM), managing the physical layer protocol with a microcontroller (MCU) such as a TI C2000™ MCU and broadcasting onto the power line with a dedicated transmitter such as an AFE032 analog front end (AFE), electrical meter companies are now able to build e-meters that will communicate from your home back to the power plant in real time, allowing not only power utility companies to automatically measure your power consumption, but also to adjust in real time their power production depending on the demands of the users.

However, some of the real challenges with e-meters are to meet specific standards of emissions to avoid interference with other means of communication (such as wireless or High-Frequency). Those standards are different depending on the region of the world you live in, making the process of manufacturing e-meters very complex. Moreover, designing a power amplifier capable of delivering in excess of 1.5A at 21Vpp can prove itself a difficult engineering task. No other single monolithic IC in the market can claim to have such capabilities while maintaining a THD + Noise below 0.003%. Admittedly, a good discrete design could meet this requirement, but it would require careful design, over 20 discrete components and would take more than 10 times the number of components required by a single IC. This is where a fully integrated analog front end could save the day.

Designed to be deployed anywhere in the world, the AFE032 integrates a power amplifier capable of transmitting a signal onto the power line via a dedicated electrical network. The power amplifier is the unique component that can either break or make the solution. Transmitting an analog OFDM signal into a low impedance power line requires a special, well-designed power amplifier that can broadcast the signal over a long distance.

This is where key specifications of the AFE032 come into play such as:

• Large output swing, up to 21Vpp
• Large output current up to 1.5A typical
• Large bandwidth in a gain of 6.5V/V or more (3.82MHz for the AFE032)
• High slew rate in a gain of 6.5V/V (75V/us for the AFE032)

Moreover, the AFE032 also incorporates several adaptable on-the-fly filters to clean up the output signal to prevent interference with other modes of communication and comply with the standards of the country the e-meter is being deployed.

The capabilities of the power amplifier coupled with the adaptable filters is what make the AFE032 a flexible solution, that can be deployed anywhere in the world with very minimal changes and time.Coupled with a C2000 MCU, the AFE032 can be configured to transmit information on the grid in Japan, France, or the U.S., with minimum changes to the e-meter and electrical configuration. This allows the e-meter manufacturer to have one design fits all approach for the smart grid.

At this point, the future of power line communications is no longer constrained to the smart grid, but a new whole new world of building automation, lighting control and smart appliances, which are flourishing all around us to make the use of the electrical network in every house and every building a new mean of communication and control. With its highly configurable approach, this is where integrated analog front end products can respond to the needs of the future of power line communication.

Discover TI’s vision for the smart grid and energy markets in this new industrial video and read our new white paper about technologies that will allow smart cities on the grid to embrace renewable forms of energy generation.

Learn more about TI’s smart grid capabilities in these blog posts featured during #OntheGrid week:

• The power of information #onthegrid, Tools Insider blog
• Engineering a smarter energy grid, On the Grid blog
• How MCUs ease solar micro inverter design, On the Grid blog

In the last electrical overstress blog we introduced the absolute maximum specification table and described how a series resistor can be used to protect the inputs from electrical overstress.  Exceeding the power supply voltage is another common overstress issue.  One possibility is that a large transient voltage is coupled into the power supply.  This can happen from inductive kickback of a load such as a motor start up.  Large transient voltage on the supply is a common problem in many real world systems, and you should always design to protect your application from this problem.

The most common way to protect against power supply transients is to have a transient voltage suppressor (TVS) on each supply.  The TVS will limit the supply voltage to a safe level so that the maximum supply voltage is not exceeded.  We introduced the TVS in the previous blog.  In this blog we will continue the discussion by explaining the TVS specifications. 

Figure 1 illustrates the typical V-I characteristics for a TVS device.  As was mentioned previously, the device behaves much like a zener diode except that it is optimized to react quickly to large transient currents.  Also, the specifications of a TVS highlight key characteristics that are important to protection against transient overvoltage.   Table 1 gives an example TVS specification.  Notice that all the specifications correspond to key points on the V-I curve.  As we describe the specifications refer to the V-I curve to help clarify the meaning of the specification.

Figure 1: V-I Characteristics for a TVS

Table 1: Example specifications for a Transient Voltage Suppressor

The reverse standoff voltage (V_R) is the normal operating voltage for the TVS device.  At this voltage level, the device is effectively “off” and will have a specified leakage current.  The leakage current (I_R) is normally in the micro-amp level.  This current adds to the total power supply current and can be a concern for low power applications. Increasing the supply beyond the reverse standoff voltage will cause leakage to increase, and the TVS will eventually breakdown when the breakdown voltage (V_BR) is reached.  Figure 1 shows where V_R is on the TVS V-I curve.  From Table 1 you can see that V_R = 18V, and I_R = 5µA in the example TVS specification.

The breakdown voltage (V_BR) is the point at which TVS protection begins to breakdown or “turn on” and starts to draw significant current.  After it breaks down, the voltage across the TVS will “clamp” to a relatively constant voltage.  From Table 1 you can see that V_BR ranges from 20V to 22.1V, with a  1mA breakdown current (I_BR) for our example TVS specification.

Referring to figure 1, notice that although the voltage is relatively constant after breakdown, there will be some voltage increase with increasing current.  The clamp voltage (V_C) is defined to help understand how voltage increases across the TVS after breakdown.  The clamp voltage is the voltage drop across the TVS when it is on and drawing significant current.  For some devices a few different clamp voltages are given at different current levels.  In this example, the TVS maximum clamp voltage is given as V_C = 29.2V at a current of I_PP = 13.7A.  In the next blog we will learn how to estimate the clamp voltage for different current levels.

In this blog, we discussed the key specifications for TVS devices.  In the next blog we will show how to select a TVS device that will protect your application. The first post in this series is here.

References:

1.      Walters, Kent. “How To Select Transient Voltage Suppressors”, MicroNote 125, July 1999. www.microsemi.com

2.      STMicroelectronics, “ESDA-1K Data Sheet”, Doc ID 17883 Rev 1, September 2010, V-I curve, Page 2. http://www.st.com/web/en/press/c2747

Welcome to another blog post in celebration of #OnTheGrid week! This blog post takes a look at the design of solar micro inverters—an emerging segment of the solar power industry and an increasingly reliable and efficient way to get power “on the grid.”

Rather than linking all solar panels in a solar installation through a central inverter, solar micro inverter systems place smaller, or “micro,” inverters in line with each individual solar panel. While solar micro inverters yield many benefits, including elimination of partial shading conditions, increased system efficiency, improved reliability and greater modularity, they can be extremely challenging for designers. They require the controller to use complex algorithms to control the power stage, synchronize with the grid using software phase locked loop (SPLL) and track to the maximum power point of the panel, along with executing complex state machines, which increases the computational load on the processor.

One of our solar power experts, systems application engineer Manish Bhardwaj, recently published an article in ECN magazineabout embedded challenges in solar micro inverters. He explains embedded challenges in control of solar micro inverters and provides insight into power stage design and control to help you mitigate these challenges. Read the full article here: http://digital.ecnmag.com/ecnmag/may_15_2014#pg26.

For more resources on solar micro inverters, check out our earlier blog posts:

• To micro or not to micro? Three main benefits of solar micro inverters for the smart grid
• Cutting-edge solar micro inverter development, uncovered!

Visit our solar solutions site for information about our products, tools and support for your next solar system.

Discover TI’s vision for the smart grid and energy markets in this new industrial video and read our new white paper about technologies that will allow smart cities on the grid to embrace renewable forms of energy generation.

Learn more about TI’s smart grid capabilities in these blog posts featured during #OntheGrid week:

• The power of information #onthegrid– Tools Insider
• New article explains how MCUs ease solar micro inverter design– On the Grid
• Engineering a smarter energy grid– On the Grid

We always appreciate the opportunity to share a customer’s success story. It’s one thing for us to tell you what our technology can do, but what really matters is the functionality and time savings that motor control system developers can achieve with our technology.

 Weal Tree, a start-up company based in Taiwan, manufactures chair lifts for the elderly. As a small company, it is very important for Weal Tree to spend less time writing motor control routines and tuning their motors so that they can get products to market quickly. By using our InstaSPIN-MOTION™ motor control software, Weal Tree estimates that they were able to reduce control software development from one year to one month! Check out the below video to learn more about Weal Tree’s success story:

 InstaSPIN-MOTION is a comprehensive torque-, speed- and motion-control software solution that delivers robust system performance at the highest efficiency for motor applications that operate in various motion state transitions. Built upon TI’s InstaSPIN-FOC™ motor control solution, InstaSPIN-MOTION is uniquely designed to optimize complex motion sequences, reduce tuning to a single parameter and track desired trajectories with unmatched accuracy across wide operating ranges. With the core algorithms embedded in the read-only-memory (ROM) on TI’s 32-bit C2000™ Piccolo™ microcontrollers (MCUs), InstaSPIN-MOTION integrates SpinTAC™ components from LineStream Technologies, featuring optimized motion profiling, single-parameter tuning and a disturbance-rejecting controller, which speeds development and increases performance across changing speeds and loads. InstaSPIN-MOTION can be used with sensored feedback or with the included FAST™ sensorless software observer.

 Want to see what Weal Tree was able to create after only one month of software development? The company has shared some videos with us so that we could see their complete chair lifts in action:

https://www.youtube.com/watch?v=kxI-zSuPgls

https://www.youtube.com/watch?v=Dyfh_b0krTE

Recently, I was privileged to showcase a project I have been intimately involved with for some time, the Analog Shield, at the TI booth at the Bay Area Maker Faire. For those not familiar, Maker Faire is something like a cross between a state fair and a swap meet. People and companies from all walks of life commingle and show off the things they are passionate about, from Leatherworking to 3D printing. TI was there to  show off the tools that enable all these amazing projects to come to life.

 The Analog Shield is part of a broader project that stems from my advisor, Greg Kovacs, and his  vision to shrink an entire electronics lab down to fit on a couple of Arduino Shields. With the proper tools, electronics lab classes can be taught anywhere in the world, even  outside the traditional lab setting. The Analog Shield is the first result of this project, using TI components to greatly improve the analog capabilities of a microcontroller platform. On the board are:

• Analog to Digital Converter (ADC)
• 4 Channel, 16 bit 100ks/s SAR ADS8343.
• Digital to Analog Converter (DAC)
• 4 Channel 16 bit 100ks/s DAC8564.
• Variable +/-7.5V Supply TPS61093.
• Fixed +/-5V Supply.
• Area for bread boarding.

 Additionally, we created a library that offers interface to the ADC and DAC with a single line of C. The board is now being produced by Digilent, and can be found at http://www.digilentinc.com/analogShield

 I’d like to take a moment to thank the wonderful team at TI who have been instrumental in moving this project forward, as well as our launch partner, Digilent, of course, the team here at Stanford who have supported this project from day one.

 In order to show off just how useful a good analog toolkit is, we envisioned a handful of demos and set about making them a reality. We thoroughly documented these demos, so hobbyists and students can reconstruct our work. These demos include a function generator, a four-voice midi player, a Lissajous diagram generator, and a spectrum analyzer.

Of all the demos built around the Analog Shield, the spectrum analyzer probably got the most attention. The spectrum analyzer uses an electret microphone and samples audio using the analog shield, then performing an FFT and displaying the output on a touch LCD. It is capable of sampling signals up to 30kHz and displays the results in real time, using no off board processing. The best part of the demo is that it came with a personal story.

 When we first built the analyzer in our lab, we discovered a loud tone at 25kHz, well outside the range of human hearing. At first, we were convinced that the tone was a problem with the analyzer or the microphone, but after finding the tone disappeared when the microphone was muffled or when the analyzer was moved into the hallway, we were able to find the source – the lab HVAC system is emitting a tone that we cannot hear, as loud as the output of our test stereo.

 Maker Faire was full of interested onlookers, with Saturday including visits from a Chris Gammell of The Amp Hour, and Alasdair Allan of Make Magazine. Dr. Kovacs also brought a group of Stanford students by who were visiting on a university outing. It seems likely that the Analog Shield will feature in more student projects in the near future.

 Sunday included video interviews with Hackaday and Make Magazine, and was capped off by a post show ‘bring a hack’ dinner and meet. Cathy Wicks, of the TI University Program took our spectrum analyzer and taped it to a swaddled in TI-red duct tape, making for a fascinating conversation piece that actually showed the conversation.

All in all, the weekend was wild and wonderful experience that allowed us to share some wonderful work that I have been but a small part of, and hopefully begin the process of bringing that product to the world.

The intent of the smart grid is to allow communication through the power supply to increase the efficiency of the energy grid. This is achieved by ensuring that any equipment connected to the power grid will not only be power efficient for the intended functionality, but will also use the energy in the most efficient manner, minimizing peak power consumption and average overall power usage. 

In order to achieve this level of efficiency, a power efficient M2M communication system is required.  At the heart of the system is a microcontroller such as the ultra-low power MSP430 MCU.  To minimize the impact on the M2M communication system efficiency, without transmitting, it is critical to optimize the power supply of the MSP430 MCU.  One way to do that is through a dynamic voltage scaling technique.

Using a dynamic voltage scaling (DVS) technique can minimize power consumption by lowering quiescent current in the system. 

Although LDOs are not renowned for their power efficiency, they can, if used appropriately, increase the power efficiency of a system. This power efficiency increase is achieved by reducing the clock speed of the MCU by reducing the supply voltage.  As the supply voltage is reduced, there is the additional advantage of reduced quiescent current further reducing power consumption.

Figure 1: MSP430F21X1 Minimum Operating Voltage vs. Clock Frequency

Since the MCU may only require peak performance during a predetermined time such as transmission, but not while monitoring other functionality of the system, implementing DVS can reduce system power consumption.

LDOs such as TPS780 make it easy to implement an integrated DVS solution.

Figure 2: TPS780 DVS Implementation

Other DVS solutions are possible by using ANY-OUT^TM LDOs such as the TPS7A83.  ANY-OUT^TM LDOs can achieve 255 different voltages with a 50mV or 100mV resolution. (Please refer to “Increasing resolution for ANY-OUT programmable output voltage devices” for additional information or individual device datasheet for more information)  ANY-OUT^TM devices have a 1A drive capability, so it would be overkill for an MSP430 MCU, but may be of interest for other higher-power circuitry requiring DVS.

Another alternative is to use two independent LDOs connected as shown in figure 3.

Figure 3: DVS using two fixed output LDOs

Enabling the high-Vout LDO forces the low-Vout LDO to stops its regulation.  Disabling the high-voltage LDO allows the low-voltage LDO to regulate again.  Transition from one LDO to the next is shown in figure 4.

Figure 4: Transition from 3.3V LDO to 1.8V LDO

Monitoring those power supplies and ensuring that no overvoltage condition is present in the system will require the use of voltage supervisors.  The TPS3831 with its extremely low quiescent current and small footprint is ideal for this task. 

Figure 5: TPS383x as MCU supervisor

For multiple voltage monitors integrated in a single package, the TPS386000 is the best candidate for integration and independent delay times.

Figure 6: TPS386000 Example Circuit

LDOs and supply voltage monitors are an essential part of managing power supply and ensuring that smart grid systems are operating at high efficiency.  If you have any questions about the DVS technique, please let me know in the comment section below!

Discover TI’s vision for the smart grid and energy markets in this new video.

Learn more about TI’s smart grid capabilities in these blog posts featured during #OntheGrid week:

• The power of information #onthegrid on Tools Insider
• New article explains how MCUs ease solar micro inverter design on On the Grid
• Engineering a smarter energy gridon On the Grid

Water is one of the most precious resources we have. The world’s population, homes, industry and draught conditions in many regions, are putting more pressure on water restrictions. Cities and communities are stepping up enforcement of restricted watering times and amounts to ensure the local water supply is protected. However, manual monitoring of water use through neighborhood drive bys or monitoring water bill amounts is not an easy task for service providers when there are hundreds of thousands of households to monitor.

But there is a better way.

Smart water meters monitor the amount of water being used, but can also provide real-time information to providers and municipalities through wireless connectivity. The long range capabilities of Sub-1 GHz wireless connectivity makes it perfect for monitoring neighborhoods from one location to get real-time usage information. This same principle can also be used to monitor electricity usage to find anomalies in a house’s consumption and locate stolen electricity lines.

This may seem a little extreme, but the real-world applications are saving water and electricity, and are even helping to stop crime.

In draught-stricken areas, it is common for water restrictions to limit lawn watering to once a week or even less and typically on a strict day and time schedule. Wirelessly connected smart meters can detect excessive consumption that would indicate improper watering and use or even a broken pipe. With accurate and timely information, utility companies can dispatch teams to investigate and determine the cause and take action – citations for improper watering or water use, notifying home or building owners of broken pipes that need to be addressed, or getting city pipes fixed.

Stealing electricity is not a new crime, but it is now one that can be detected by adding wireless connectivity to electricity meters. Much like monitoring water meters, utility companies can monitor for unusual electricity consumption to determine if a home’s or building’s electricity has been compromised.

So how does water and electricity monitoring stop crimes other than locating stolen services?

Police are using the real time monitoring highlighted above to help identify illegal drug farms because of the large amounts of water and electricity needed to grow crops. Taking a high-tech approach, police and governmental agencies use wirelessly connected transformers and meters to more precisely pin-point where these farms are located by studying large spikes in usage.

Wireless connectivity is revolutionizing several areas of smart metering by providing easier maintenance, billing and support beyond monitoring for utility abuse. Read this whitepaper for more information on how wireless connectivity is enabling a smarter grid.

Learn more:

• TI’s SimpleLink Sub-1 GHz CC1200 smart RF transceiver and Sub-1 GHz high performance family
• TI’s smart grid solutions

Discover TI’s vision for the smart grid and energy markets in this new industrial video and read our new white paper about technologies that will allow smart cities on the grid to embrace renewable forms of energy generation.

Learn more about TI’s smart grid capabilities in these blog posts featured during #OntheGrid week:

• The power of information #onthegrid – Tools Insider
• New article explains how MCUs ease solar micro inverter design – On the Grid
• Engineering a smarter energy grid – On the Grid
• Configurable AFEs change the future of power line communications  – Analog Wire
• Stopping utility fraud and abuse with wirelessly connected smart meter monitoring – ConnecTIng Wirelessly

If your next product had an efficiency of 30%, would you advertise it as a feature?  Or might you contemplate burying this fact deep down in the user’s manual or other documentation?  For many simple systems that use tried and true, linear regulators (LDOs) as their power supply, the efficiency may not be much more than 30%.  Or it may never be that high at all.

While LDOs are extremely simple, low noise, and very low cost, the main barrier of the LDO is its waste.  It doesn’t actually ‘convert’ power from a higher to a lower voltage.  Rather, it dissipates power to give you a regulated output voltage.  This is simple and low cost, but for many high voltage systems such as those powered by 3-cell lithium batteries and higher voltage AC adaptors it is too inefficient.  At heavier loads, the LDO may create significant heat which must be removed from the system.  This heat creates a further reliability issue for both the LDO and its adjacent components, if the temperatures become too high due to the higher power dissipation.  But for low power, low cost systems that have no thermal concerns, the LDO is still very much a viable and frequently chosen option.

Modern day Switch-mode Power Supplies (SMPSs) are almost as simple as LDOs, but much more efficient.  Efficiencies are typically in the 80-90% range for most operating conditions.  This results in much less power dissipation, which equates to lower operating temperatures, increased reliability, and longer battery run time.

Finally, even at very low output currents, where LDOs are usually more efficient than a corresponding SMPS, SMPSs have come a long way to closing this gap.  Ultra-low power operating modes, such as deep sleep and standby modes, keep the SMPS efficiency at higher levels down to even lower load currents.  As I detail here, until the load current decreases to 10 µA, the TPS62177SMPS is still more efficient than a 1-µA I_q LDO.  If your system is a smoke alarm with very low current consumption for most of the time, then an LDO may be a better solution considering the low cost of such end equipment, low noise needed for the sensitive sensors, and higher efficiency at the lower power operating point.  But if you are powering a notebook, which has higher standby power consumption and much higher peak power consumption, does not need low noise, and is not a lowest cost system, then the SMPS offers advantages.

Which do you prefer, SMPS or LDO?  Let me know what you think, after reviewing all the details that I discuss here.