App note: Driving brushless long-life vibration motors

App note from Precision Microdrives on new brushless motor design and how to drive them efficiently. Link here

For a long time, all motors driven by DC supplies relied on using metal or carbon brushes to provide electrical power to the motor’s internal components. Meanwhile, in larger motor designs it has also been possible for over 100 years to create a rotating motor without using brushes, by using an AC power supply.
In using the same design as traditional 3-phase AC motors, the problem with using ‘brushless motors’ powered from a DC source, was not the motor itself, but the driver. It wasn’t until digital signal processing and highly integrated circuits arrived, that driving brushless motors powered from a DC source became feasible.
These brushless motors tend to be more efficient, but the major benefit is the extended lifetime. This means they are popular in products that require prolonged or constant rotation. In the past, DC brushless motors have been used devices such as VCRs, printers and hard disk drives.
High time, therefore, to apply the reliability of brushless motors to vibration applications. In particular, fields like mechanical aid can require constant vibration to aid the flow of, for example, medicine pills through a chute. A well made brushed vibration motor may last up to a thousand hours or more, which is more than enough for a handheld product that rarely vibrates in short bursts. But when constantly running rates this would require a motor change every 5~6 weeks

App note: Using SPICE To model DC motors

App note from Precision Microdrives helping you model DC motors in SPICE. Link here

SPICE (Simulation Program with Integrated Circuit Emphasis) is an open-source program for simulating electrical circuits. It enables engineers to model the behaviour of their circuits in software, which reduces prototyping costs and time.
As DC motors have mechanical properties – i.e. they cannot be simulated accurately only considering electrical properties – it can be difficult to use them in SPICE. This Application Bulletin guides you through the principle of operation and extends the DC motor model for vibration motors and gear motors.

App note: High-side current sensing for applications using high common-mode voltage

App note from STMicroelectronics. Link here (PDF)

This application note explains how to extend the common input voltage range of a standard operational amplifier (op amp) to realize a high-side current sensing.

App note: Introduction to comparators, their parameters and basic applications

App note from STMicroelectronics about comparators and their limitations, also info on substitution depending on the application. Link here (PDF)

After operational amplifiers (op amps), comparators are the most generally used analog, simple integrated circuits.
Operational amplifiers are well described in many publications and a lot of information can be found regarding the design and proper use of these devices. On the other hand, information concerning comparators is much harder to find as they are often considered as simple devices.

App note: Power inductors 101

App note from Vishay about how modern power inductors are made and their performance. Link here (PDF)

Power inductors are typically used for energy storage in DC/DC converters or high current noise filter applications, including motor speed control, adjustable lighting, DC power conditioning, and more. Power inductors can be divided further into two groups – shielded and unshielded. Unshielded power inductors have an open magnetic circuit where the magnetic flux induced in the core by the current in the winding exits the core and extends through the air to the other side of the core where it completes the flux path.

App note: Inductors as RF chokes

App note from Coilcraft on how inductors where used for solving RF isolation issues. Link here (PDF)

Many consumer products communicate with each other over broadband networks. From television to fiber transmission networks, the bandwidth of data communication is increasing, and the integrity of RF signals has become a major design concern. This paper provides examples of how different inductors can be used for RF isolation in a range of circuits from relatively narrow band applications like portable devices up to broadband networks for data distribution. The different types of inductors used in these applications are identified and discussed.

App note: Measuring self resonant frequency

App note from Coilcraft on determining the self resonant of an inductor and how to compare them to other identical inductors. Link here (PDF)

When comparing published electrical values, engineers require a common basis for comparison. Ideally, a 100 nH inductor with a self resonant frequency (SRF) of 1 GHz from one manufacturer is equivalent to inductors with the same published values from every other manufacturer. Realistically, however, the test instrument and fixture affect the SRF measurement. Since all manufacturers do not use the same instruments and fixtures, not all published SRF specifications are equivalent, which makes inductor comparisons difficult.

App note: Utilizing the power shutdown capabilities of the Kionix tri-axis accelerometers

Conserve power on using accelerometers with the help of this app note from Kionix by shutting it down on specific operating duty cycle. Link here (PDF)

Kionix tri-axis accelerometers feature a power shutdown capability. Even with their typically low current draw, there are still applications that may require even less power consumption. For these applications, it is possible to implement a duty-cycle powerreduction methodology that uses a microprocessor to toggle the Enable/Disable pin or register at a specified duty-cycle. This approach can reduce greatly the accelerometer’s current draw during the majority of its time in operation. This application note provides the theory and equations needed to take full advantage of this power saving capability.

App note: Multiplexing Tri-Axis accelerometer outputs

App note from Kionix on reading multiple accelerometer by a single ADC using off the shelf chip or accelerometer built-in multiplexer. Link here (PDF)

A Kionix tri-axis accelerometer with analog outputs provides three output voltages (Xout,Yout, Zout) which are proportional to the respective accelerations in those directions. However, with three analog outputs to digitize, it is possible that the system microprocessor does not have the necessary A-D converters. One solution is to use the internal multiplexing capability of several Kionix accelerometer products to multiplex the three outputs to one analog signal. Another solution is to use an off the shelf multiplexer to multiplex the three outputs of the tri-axis accelerometer to one analog signal.

App note: Smart battery charger by LPC845 with SMBus interface

Battery charger using NXP’s LPC845 through SMBus communication. Link here (PDF)

Batteries are used everywhere, such as smart phones, notebook computers, wearable devices, handheld electronic products, smart small appliances, etc. Users always want to know the battery temperature, voltage, current, capacity, how long it can be fully charged, and how long the battery will be exhausted. During the charging process, it is very important to ensure the safety of battery charging and provide a smooth and controllable charging curve. The above requirements are expected to be realized by a smart charger. A smart charging solution implemented with LPC845 is recommended.

App note: Low-Power Real-Time algorithm for metering applications

Tested algorithm library from NXP Semiconductors on power metering. Link here (PDF)

High accuracy metering is an essential feature of an electronic power meter application because inaccurate metering can result in substantial amounts of lost revenue. Moreover, inaccurate metering can also undesirably result in overcharging to customers. The common sources of metering inaccuracies, or error sources in a meter, include the sensor devices, the sensor conditioning circuitry, the Analog Front-End (AFE), and the metering algorithm executed either in a digital processing engine or a microcontroller.

App note: Loudspeaker characterization and compensation

Using DSP and ST’s Tune software to compensate for a flatter response on speakers discussed in this app note from ST Microelectronics. Link here (PDF)

The application note describes how to measure and analyze the performance of a loudspeaker and how to compensate the frequency response using the ST Speaker Tune software, a tool available in the APWorkbench.

App note: Pre-amplifying the analog output of a MEMS microphone

Designing pre-amp for MEMS microphone found in this app note from ST Microelectronics. Link here (PDF)

This application notes describes the key parameters related to pre-amplification of the output signal of an analog MEMS microphone (MP23AB02B). A solution is proposed based on the TS971 op amp. For a differential output configuration, we can consider using the TS472. The information in this document should allow you to design your own circuit suitable for your application.

App note: The importance of compensation capacitors on the eFuse power line

Inductive spike on voltage rails causes eFuse to shutdown, here’s an app note from ON Semiconductors on how they solve this problem from happening. Link here (PDF)

ON Semiconductor produces a wide variety of silicon based protection products including current limiting devices such as Electronic Fuses (eFuses). During an over−current stress, eFuses can limit the current applied to a load as well as remove power from the load entirely. This fundamental feature of the eFuse makes it an easy choice to protect against inrush currents which can be seen on power lines of hard−disk drive (HDD) and enterprise−server systems during hot−plug operation or load−fault conditions. During the eFuse current limiting operation, the threat exists of an inductive spike on the power line (VCC) at the point of device turn−off due to thermal shutdown. This Application Note will discuss the failure mechanism this threat exposes the eFuse to, and will explain how to combat it by adding compensation capacitors onto the power line when using the auto−retry (MN2) version of the eFuse.

App note: eFuse reverse voltage protection

App note from ON Semiconductors about eFuses’ ability to block reverse voltage. Link here (PDF)

One area in which they (eFuses) differ in performance is reverse polarity protection. While a TVS device and polyfuse will protect against reverse voltages, the nature of an integrated semiconductor device does not inherently allow for this type of protection.
This simple circuit allows the device to protect against reverse voltage situations by simply blocking the reverse voltage. This is equivalent of the action of a poly fuse only with less leakage. In comparison to a mechanical fuse, this is a far superior solution since the mechanical fuse will not reset and this circuit will automatically reset when the correct voltage is applied.

App note: Implementation of error code correction in EEPROMs

App note from ON Semiconductors about their EEPROM error correction. Link here (PDF)

Some of ON’s automotive EEPROMs, like the Grade 0 NV25xxx family (SPI, 1 – 64 Kb) and the Grade 1 CAV24Cxx / CAV25xxx (Grade 1, 128 Kb and higher) implement an Error Code Correction scheme. What this means is that for each chunk of data in the EEPROM array (8 bits for 1 – 64 Kb densities, 32 bits for 128 Kb and higher), the memory stores a redundancy code in separate EEPROM cells.

App note: Revolutionizing analog to digital conversion

App note from ON Semiconductors introducing their nano power ADC NCD9801x. Link here (PDF)

The NCD9801x ADC is a differential 12−bit resolution successive approximation register analog−to−digital converter unlike any other SAR ADC available on the market. It uses an innovative design to keep a low input capacitance of 2 pF, easily besting the typical SAR ADC input capacitance. The analog power consumption of the NCD9801x converter can reach nano−Watt levels during conversion and can be scaled dynamically based on the clock rate. These two unique traits allow designers to utilize the NCD9801x in design applications that have previously been unachievable.

App note: Applications of current DACs

App note from Maxim Integrated about current DACs and their uses. Link here

The worldwide use of the electronic devices creates high demands for DACs to connect digital systems to the analog world such as the fiber optical communication networks, to bias photo diodes or to digitally control analog devices such as power supplies to precisely deliver stable, high-resolution currents from the very low microamps to hundreds of milliamps. The output stage of a DAC can be designed to provide a voltage or current output. This application note discusses the current output type and its intended applications.

App note: Design and application guide of bootstrap circuit for high-voltage gate-drive IC

A deeper dive into controlling gates of MOSFETs with boostrap circuits talked in this app note from ON Semiconductors. Link here (PDF)

The purpose of this paper is to demonstrate a systematic approach to design high−performance bootstrap gate drive circuits for high−frequency, high−power, and high−efficiency switching applications using a power MOSFET and IGBT. It should be of interest to power electronics engineers at all levels of experience. In the most of switching applications, efficiency focuses on switching losses that are mainly dependent on switching speed. Therefore, the switching characteristics are very important in most of the high−power switching applications presented in this paper. One of the most widely used methods to supply power to the high−side gate drive circuitry of the high−voltage gate−drive IC is the bootstrap power supply.

App note: Understanding eFuse input voltage transients from hot plug events

App note from ON Semiconductors about things to look for when hot plugging eFuses. Link here (PDF)

System designers must account for voltage surges that occur when supplies or loads are connected. eFuses are integrated circuits with many features to protect loads from these surges. However, it is important to ensure that the eFuse itself will not receive excessive voltage on its input. This application note uses mathematical calculations, simulations, and actual lab data to illustrate the voltage surge as an eFuse is suddenly connected on the input side. System designers can use this information to make certain that the eFuse will be within its limits.