The Kynix Blog

  Do you know Dallas Semiconductor which is owned by Maxim Intergrated now? It's well known for making some excellent real-time clocks(RTCs). Let me take an example: DS1307 is simple,works with essentially any cheap 32,768Hz watch crystal,is easily accessible over I2C,and is extremely power efficient( 500nA current when running the oscillator on battery power). As great as it is, the DS1307 has a major drawback: it relies on an external crystal and lacks any sort of temperature compensation. Thus, any change in temperature will cause the clock to drift. A 20ppm error in the frequency of the crystal adds up to about a minute of error per month. Not so great. Well,it does not matter. It's fortunate that Maxim offers DS3231 which is called as an “Extremely Accurate I2C-Integrated RTC/TCXO/Crystal”.This chip has 32kHz crystaql integratrf into the package itself and uses a built -in temperature sensor to periodically measure  the temperature of the crystal and, by switching different internal capacitors in and out of the crystal circuit, can precisely adjust its frequency so it remains constant. It’s specified to keep time within 2ppm from 0°C to +40°C, and 3.5ppm from -40°C to +85°C, which means the clock would only drift 63 and 110 seconds per year, respectively. So cool. The one (very minor) downside is that it draws about twice the current, a bit less than 1 μA, than the DS1307. Still, a common 220mAh CR2032 battery could power the chip for at least a decade with no problem. Such a circuit would be mostly limited by the CR2032’s self-discharge rate anyway. In my case, I wanted to use such RTCs on several of my Raspberry Pis that are not regularly (read: almost never) connected to the internet, and so cannot always get their time from NTP servers. Some great people have designed a simple board that fits on the Raspberry Pi's pin headers for power,ground and I2c and own the DS3231,pull-up resistors for the I2C bus, and a decoupling capacitor. It even has pads for a backup battery (not included, but adding a battery holder and coin cell is straightforward). Chinese vendors on eBay sell the board for about $1.50, with free shipping. Perfect. The above picture is the board I am using on my Pis,along with the backup battery and holder I added. Well,I think this condition should be considered in that DS3231 is more expensive than a complete board.Well, I am so curious and I wondered if these were counterfeit chips that were pin and function compatible, QC rejects, or somehow otherwise illegitimate chips. For science, I ordered a few extra boards and tested them over the last year, where “tested” means “set the time on the chips with a Pi that was NTP synchronized to a GPS timing receiver, disconnected them from the Pi, and left them on the shelf running on battery power for a year”. The chips would be in direct sunlight in the mornings, and the temperature in the room would range between about 15°C and 30°C throughout the year. Not extreme, but not precisely regulated either. I did not adjust the “aging register” in the chip to trim the oscillator before this test, and the register was set to its default value of “0”. After a year, the chip with the largest drift was only 16 seconds off, which is about 0.5 ppm. That’s well within spec, so I’m happy. If these chips were counterfeit, they were at least good counterfeits that worked as advertised. However, I wanted to look closer so I sacrificed one of the chips for science. Thanks to my friend Jesse for reminding me that I can just snip off the legs of the chip rather than trying to de-solder it. That made things a lot easier. Here’s the top of the package. It claims to be an SN model, which means it is specced for the full -40°C to +85°C temperature range. The date code says it was made in week 33 of 2011, as part of lot 917AC. The # mark means it’s RoHS compliant. The laser markings seemed a bit dodgy and not like the normal high-quality laser markings I see on other Maxim chips. I contacted Maxim, explained the situation, and sent photos of the package and die (see below). After checking their records, they say the style of the markings, the date code, and lot number are all consistent with that particular lot made in 2011, which strongly suggests the chips are legitimate. They also reminded me that they do not warrant or guarantee any products purchased from unauthorized resellers! ! !( Buy DS3231 chip,go to kynix )Good to know, and not unexpected. I zoomed in with my USB microscope to examine the markings in more detail. It’s a bit hard to see in this close-up, but you should be able to see the digits “31”. Obviously, Maxim must have different types of laser marking equipment on their different production lines.  I normally would digest the epoxy packaging of the chip in acid at work, butI was at home that day and didn’t have access to the chemicals and safety equipment I have in the lab at work, plus I didn’t want to dissolve the integrated crystal and its metal can. Instead, I embrittled the packaging by heating it in the flame of a common Bic lighter for several seconds and then quenching it in a glass of cool water. I repeated this process several times. Next, I sanded down the back of the ship (assuming that the interesting parts of the die would face upwards, which they were — if they hadn’t been on the top, I’d sacrifice another chip and sand the top down) with fine sandpaper until I hit metal. It turns out I was a bit too vigorous in my sanding, and accidentally sanded through the crystal’s metal housing and broke one of the forks of the tuning fork oscillating element.Oops. In the photos below, the notch on the chip is to the left, so pin 1 is to the top left. The main die is behind the large copper pad to the left. The fuzzy “hair” at the bottom are strands of the epoxy package that I didn’t clean up.  Let's do a comprehensive observation. This was interesting, but even after Maxim said the packing and exterior markings looked legitimate, I was curious if the die itself was an actual Dallas/Maxim die or if it was a fake. Using tweezers and a fine, sharp knife I was able to crumble away more of the epoxy package and remove the die. Unfortunately, the bond wires were still embedded in the package and so broke off when I removed the die. I also slightly scratched part of the die and cracked off part of the top-right corner. Clearly, acid digestion is the way to go. Here’s the first look at the die itself. I had washed it with isopropanol and both the chip and the microscope slide are a bit wet. The die measures ~3.6 x 2.3 mm, and the images below were taken with my USB microscope.    First, I wanted to check to see if the die was actually made by Maxim or if it was a fake. The die clearly says “DALLAS SEMICONDUCTOR”, as well as “©2004 (M) MAXIM”. Looks legit. That’s refreshing.  In addition to my cheap USB microscope at home, I was later able to take the die into the lab at work and use the (very expensive) Zeiss microscope to take more pictures. I was also able to clean it more thoroughly using the ultrasonic cleaner so the images came out considerably better. Alas, compatibility issues between the camera mounted on the microscope and my computer prevented me from using the camera to get high-quality photos at this time. I’ve ordered an adapter so I can get better photos, but it will be several weeks. At that time I will either update this post or link to a new one. I plan on creating large composite images of the die at various levels of zoom, and with different optical filters. In the interim, here are a few photos I took using my smartphone aimed through the eyepiece of the lab microscope. They are nowhere near as clear or stunning in appearance as they are when viewed directly through the eyepiece or via the on-scope camera.  One days ago.I’ve been able to get the camera on the microscope to cooperate and have gotten several high-quality photos. As the microscope has an extremely short depth of focus, particularly at high magnification, some images have been “focus stacked” by combining several images at different focus depths. Similarly, the large composite images are made from several individual images that may be focused slightly differently from each other. These processes may cause visual artifacts to be present.  In general, images with green and red colored layers use standard reflected microscopy with no filters, while images with blue and gold layers use reflected differential interference contrast (DIC). That's all. Hope you like this observation about DS3231 real-time clock as me. 

SummaryWe know that empty batteries are easy to recognize.However,it is much more complicated to know the charge status between full and empty.A complete new approach with ultrasound pluses offers a precise and simple method. Batteries are used in many "mobile" technologies,and that is why it is the snag in "mobile" technologies. Like smartphones,drones,or electric cars-in many cases he time between battery charges is much too short for many people. This is why it is important to determine the exact state of charge. But this is more complicated than you would imagine. Currently, battery management systems (BMS) carry out the necessary measurements. They calculate the state of charge for each cell based on the parameters current and voltage.  However, since the calculations are partly based on standard values, they reflect the current state only approximately. In particular, this is very inaccurate in case of frequent partial charges. The battery management systems also consume some of the energy that was actually to be used for the next song or mile. About the aboving picture:Sensors with 1 cm and 2 cm diameter to measure the state of charge of the battery Battery Management with UltrasoudIn the future this will be more reliable, more energy saving and cheaper with sensor systems that are being developed in the SoCUS project at the Fraunhofer ISC. They measure the density of the negative anode with the help of ultrasound pulses. This changes as the state of charge of the cell changes.The method has several advantages: there is a direct linear connection between the state of charge and the measurement signal. This makes the evaluation simpler and more precise than with the technologies currently in use.The new battery sensors can be easily integrated into existing systems.One evaluation unit can monitor several battery cells simultaneously and measures the state of charge only during charging and discharging. The fact that this system does not check the charge continuously saves energy and, consequently, costs.Since the ultrasound signal correlates directly with the mechanical properties of the cell, all aging processes are taken into account better. This allows more accurate statements to be made about the current remaining capacity and, hence, the performance.  About the above picture: Principle of the state-of-charge estimation by ultrasonic pulsed excitations: A RCN-pulse transmitted through the cell gives rise to two wave packets (wave I and II), where the slower (wave II) ones' amplitude shows a linear relationship on the state-of-charge. For optimized signal strength of-the-shelf piezo transducers are attached centered on opposite sides of commercial pouch-type cells. Battery Management with All TypesThe new measuring method is suitable for almost all types of battery. However, to date only lithium ion batteries have been tested. In particular, electric vehicles should benefit from reliable recording of the battery charge status. After all, the distance covered between charges is the key factor for further development. But reliable monitoring of the state of charge is also important for drones that monitor industrial plants and wind parks or that manage agricultural land. The ultrasound method could be especially profitable for stationary storage systems with a large number of connected battery cells. A sensor that works only when required and records the state of charge of several cells simultaneously can save energy and also costs. In this application, flame retardant battery types are often used where the state of charge cannot be determined accurately with current methods. The new method could extend existing measurement methods of battery management systems in the future, especially also in electric mobility with a reliable, energy-saving, inexpensive variant. 

Linear Technology announces the LT3760, an 8-channel LED driver, utilizing a step-up DC/DC controller capable of driving up to a 45V string of 100mA LEDs per channel. Its internal 60V, 1MHz DC/DC boost mode controller is designed to operate as a constant current LED driver for up to 80 white LEDs. From a 12V input, the LT3760 can drive 8 channels, each with up to ten 100mA white LEDs in series while delivering efficiencies exceeding 92%. Its multichannel capability makes it ideal for medium and large-sized TFT-LCD backlighting applications. Its input voltage range of 6V to 40V makes it ideal for automotive, avionic, HDTV and industrial display applications. The LT3760 offers ±2.0% (±0.7% typical) LED current matching to ensure uniform brightness of the display. Dimming ratios as high as 3,000:1 can be attained by using True Color PWM™ dimming. A programmable 100kHz to 1MHz fixed frequency operation and current mode architecture offers stable operation over a wide range of supply and output voltages while minimizing the size of the external components. Additionally, the switching frequency is synchronizable to an external clock. Its thermally enhanced TSSOP-28 package offers a highly compact solution footprint for most LED backlighting applications. The LT3760 uses an external N-Channel MOSFET switch to provide a boost mode constant current source. However, even when VIN exceeds VOUT, the LT3760 will continue to accurately regulate the LED current. The internal boost controller uses an adaptive feedback loop to drive up to eight channels of ten 100mA LEDs to regulate the output voltage slightly higher than the required LED voltage to ensure maximum efficiency. If any of the LED strings experience an open circuit, the LT3760 will continue to regulate the existing strings and signal the FAULT alert pin. If higher current LEDs are required, multiple strings can be combined, enabling the LT3760 to drive up to four channels of ten 200mA LEDs or two channels of ten 400mA LEDs. Additional features include programmable LED current derating based on junction temperature and LED temperature and programmable output voltage limiting when all LED strings are disconnected. Summary of Features LT3760: Up to 45V of LEDs × 100mA, 8-Channel LED DriverWide Input Range: 6V to 40V±2.0% LED Current Matching at 20mA (Typ ±0.7%)Up to 3000:1 True Color PWM™ Dimming RangeSingle Resistor Sets LED Current (20mA to 100mA)LED Current Regulated Even for PVIN > VOUTOutput Adapts to LED VF for Optimum EfficiencyFault Flag + Protection for Open LED StringsProtection for LED Pin to VOUT ShortParallel Channels for Higher LED CurrentProgrammable LED Current Derating vs. TemperatureAccurate Undervoltage Lockout Threshold with Programmable HysteresisProgrammable Frequency (100kHz to 1MHz)Synchronizable to an External ClockThermally Enhanced 28-Pin TSSOP Package. The LT3760EFE is available in a thermally enhanced 28-lead TSSOP package in Kynix now. An industrial grade version, the LT3760IFE is tested and guaranteed to operate from a -40°C to 125°C operating junction temperature. Ref.KY32-LT3760EFE 

Eight years ago, Ted Adelson’s research group at MIT’s CSAIL unveiled a new sensor technology, called GelSight, that uses physical contact with an object to provide a remarkably detailed 3D map of its surface. Now, by mounting GelSight sensors on the grippers of robotic arms, two MIT teams have given robots greater sensitivity and dexterity. The researchers presented their work in two papers at the International Conference on Robotics and Automation.In one paper, Adelson’s group uses the data from the GelSight sensor to enable a robot to judge the hardness of surfaces it touches — a crucial ability if household robots are to handle everyday objects.In the other, Russ Tedrake’s Robot Locomotion Group at CSAIL uses GelSight sensors to enable a robot to manipulate smaller objects than was previously possible.The GelSight sensor is, in some ways, a low-tech solution to a difficult problem. It consists of a block of transparent rubber — the “gel” of its name — one face of which is coated with metallic paint. When the paint-coated face is pressed against an object, it conforms to the object’s shape.The metallic paint makes the object’s surface reflective, so its geometry becomes much easier for computer vision algorithms to infer. Mounted on the sensor opposite the paint-coated face of the rubber block are three colored lights and a single camera.“[The system] has colored lights at different angles, and then it has this reflective material, and by looking at the colors, the computer … can figure out the 3D shape of what that thing is,” explains Adelson, the John and Dorothy Wilson Professor of Vision Science in the Department of Brain and Cognitive Sciences.In both sets of experiments, a GelSight sensor was mounted on one side of a robotic gripper, a device somewhat like the head of a pincer, but with flat gripping surfaces rather than pointed tips.For an autonomous robot, gauging objects’ softness or hardness is essential to deciding not only where and how hard to grasp them but how they will behave when moved, stacked, or laid on different surfaces. Tactile sensing could also aid robots in distinguishing objects that look similar.In previous work, robots have attempted to assess objects’ hardness by laying them on a flat surface and gently poking them to see how much they give. But this is not the chief way in which humans gauge hardness.Rather, our judgments seem to be based on the degree to which the contact area between the object and our fingers changes as we press on it. Softer objects tend to flatten more, increasing the contact area.The MIT researchers adopted the same approach. Wenzhen Yuan, a graduate student in mechanical engineering and first author on the paper from Adelson’s group, used confectionary molds to create 400 groups of silicone objects, with 16 objects per group. In each group, the objects had the same shapes but different degrees of hardness, which Yuan measured using a standard industrial scale.Then she pressed a GelSight sensor against each object manually and recorded how the contact pattern changed over time, essentially producing a short movie for each object. To both standardise the data format and keep the size of the data manageable, she extracted five frames from each movie, evenly spaced in time, which described the deformation of the object that was pressed.Finally, she fed the data to a neural network, which automatically looked for correlations between changes in contact patterns and hardness measurements. The resulting system takes frames of video as inputs and produces hardness scores with very high accuracy.Yuan also conducted a series of informal experiments in which human subjects palpated fruits and vegetables and ranked them according to hardness. In every instance, the GelSight-equipped robot arrived at the same rankings. Ref:KY45-AT42QT1110-AUKY45-STMPE1208SQTRKY45-MPR032EPR2

In the future, a new sensor cable could be used to protect airports, industrial complexes and people’s yards without a great deal of expense. It registers even the tiniest changes in the Earth’s magnetic field.Plenty of things go unnoticed by our senses. One of them is the Earth’s magnetic field. Unlike migratory birds and sea turtles, we need technical aids to make use of it. Like the good old compass. It has been helping seamen navigate the seven seas since the 12th century. Sort of a primitive precursor of today’s magnetic field sensors. Then in 1832, mathematician and physicist Carl Friedrich Gauss laid the cornerstone for modern magnetic sensor technology when he developed a method for measuring both the direction and intensity of the Earth’s magnetic field.Since then, magnetic-field sensors have become quite important because they make entirely new solutions for difficult measuring tasks possible. And not just for research and industry—also for our private lives. For example, they help determine location and position in our smartphones. And with Apps such as Telemeter 11th, they even turn a digital Swiss knife into a metal detector.Magnetic burglar alarmSaarland University’s “All-round Warning Alarm” is based on a similar principle. When attached to fencing, a thin magnetic field sensor cable can tell whether the wind, a bird or wire cutters are “interacting” with the wire mesh. Buried in the ground of future traffic-guidance systems, it can tell which direction automobiles are driving. Not even smartphones or zippers can go undetected. That is because everything within a few meters that influences the Earth’s magnetic field is registered by highly sensible magnetic field sensors and transmitted to a smartphone via Bluetooth.The sensor cable is flexible and can be adapted to a wide variety of requirements, and it consumes very little electricity. It is also practically wear free, and measurements do not dependent on weather conditions. In addition, no data is stored and the sensor system has proved a hard nut for hackers to crack.The technology is based on the fact that the Earth’s weak magnetic field (approx. 50 microtesla) is always everywhere. And that every ferromagnetic object measurably disturbs this field for magnetic field sensors with sensitivities in the nanotesla range. Corresponding electronics and algorithms then determine metallic properties, size and direction of motion. Every type of “disturbance” has its own magnetic fingerprint.Magnetic field sensors for every purposeResearchers have been working a “magnetic” recognition systems for a good 15 years. As part of the development process, experiments were conducted with so-called AMR (anisotropic magnetoresistance) and GMR (giant magnetoresistance) sensors. The latter can be found in billions of read heads in hard disk drives, and the physicists who discovered them, Peter Gruenberg from Forschungszentrum Jülich and Albert Fert from Université Paris-Sud, were awarded the Nobel Prize in Physics in 2007. Both work sensors are based on the so-called magnetoresistance effect, which says that ferromagnetic materials change their resistance in a magnetic field.Burglars in a “tunnel”The first trials with the third member of the magnetoresistance team, i.e. GMI (giant magnetoimpedence) sensors, are now underway in Saarland. In this case, impedance (alternating current resistance) depends on the intensity of an applied, relatively weak external magnetic field.But that’s not all: The prototype recently introduced by Saarland University researchers uses a fourth variant, i.e. TMR (tunnel magnetoresistance) sensors, which have only been commercially available for a short time. As the word “tunnel” suggests, these magnetic field sensors make use of quantum mechanics effects. Due to their high change in resistance of 20%, TMRs are extremely interesting for a number of applications. They are provided by Sensitec(Germany), one of the partners in this project, which is sponsored by Germany’s Federal Ministry of Research.With the exception of the AMR effect, all magnetoresistance effects were discovered after 1988. In other words, this is still a relatively new, rapidly growing research sector with the prospect of extraordinary sensor solutions for various electronics sectors in the years to come. It will be interesting to see what happens! Ref:KY45-HMR3400KY45-HMC6343KY45-HMC2003

SummaryA digital temperature sensor IC which offers accurate measurements in the temperature range -20 to 10°C has been introduced by ams. The performance of the AS6200C makes it easier for designers of refrigerators and data loggers in cold-chain storage equipment to meet demanding targets for system-level accuracy. The AS6200C’s measurements are accurate to ±0.2°C between -20°C and 10°C, the temperature range over which storage equipment for perishable goods operates.  AS6200C Sensor ICAS6200C sensor's accuracy is guaranteed over the device's supply voltage range of 1.8~3.6V. In temperature control and temperature logging applications, the total error budget is made up of multiple components. By minimising the error at the point of measurement, the designer gains extra headroom for other error and noise sources, such as the heat generated by board-mounted com-ponents. The use of the highly accurate AS6200C gives the designer more flexibility to modify other elements of the system design while keeping total error below a specified maximum level. The AS6200C integrates a sensor front end, 12-bit analogue-to-digital converter and digital logic in a small WL-CSP package. It provides a digital output over an I2C interface to any host microcontrol-ler. The device performs on-board digital signal processing, which means that it needs no user calibration, and its linearised output requires no compensation by an external microcontroller. The AS6200C is intended for use in equipment for storing and transporting food, pharmaceuticals, flowers and other perishable goods, as well as in domestic and commercial refrigerators. It is well suited to data loggers that comply with the EN12830:1999 class 1 standard.The new device extends the ams family of small, accurate digital temperature sensor ICs, joining the AS6200 sensor, which achieves peak accuracy between 0 and 65°C. “The AS6200C offers the market a unique combination of small size - its footprint is only 1.5mm2 - very high accuracy over the cold-chain monitoring and storage temperature range, and a convenient digital output requiring no calibration or linearisation. It provides a new example of the value of the low noise, high sensitivity, high linearity semiconductor technology underlying the outstanding performance of ams' sensor solution products,” said Nikolai Haslebner, Marketing Manager at ams.