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.

App note: Lithium-Ion cell fuel gauging with MAXIM battery monitors ICs

App note from Maxim Integrated on accurately measuring battery capacity by using battery monitors and fuel gauge plus software. Link here

Determining the remaining charge of a Lithium-Ion cell accurately under real world conditions requires much more than just coulomb counting. The DS2438’s integrated current accumulator (ICA) provides an accurate measurement of cell capacity under known conditions, however in applications where temperature and discharge rates vary and the cell’s capacity degrades with aging, the DS2438’s ICA needs to be adjusted to achieve the desired accuracy. This document shows how the fuel-gauging concept of the DS2438 can be expanded to insure greater accuracy under extreme operating conditions. This is accomplished by characterizing cell capacity over temperature and rate and controlling the coulomb count in software. This process is not limited to just the DS2438 or a specific type of Lithium-Ion cell. Any Maxim Battery Management device with a coulomb counter, temperature converter, and 15 bytes of user EEPROM is capable of performing high accuracy fuel gauging on any type of Lithium-Ion cell.

App note: Implementing a practical off-line Lithium-Ion charger using the UCC3809 primary side controller and the UCC3956 battery charger controller

App note from Texas Instruments about Li-Ion battery charger design. Link here (PDF)

A primary goal in the design of any portable electronic device is to make the product as small and lightweight as possible. When the device is powered by a rechargeable battery, a means of charging the battery from the AC line must be provided. Although battery charging is often thought of as a secondary function, the proper implementation of a charging system can ultimately determine the success of a product.
This paper will describe a 120VAC off-line charger that is based on a two series cell Lithium-Ion pack with a 1200mA hour capacity rating. The design described here can be modified to address different line and pack voltages. The paper will address the recommended charge algorithm for the pack, primary and secondary circuitry design, feedback loop compensation, and magnetic design for the converter.