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.

App note: Vishay load dump TVS series for 24 V powertrains

App note from Vishay on the changes to the load dump test condition and defines the maximum surge suppressing capability for Vishay load dump TVS series in these conditions. Link here (PDF)

As more trucks and buses are built with complex electrical systems, load dump protection is becoming an important safety feature for vehicles with 24 V powertrains.
The function of a load dump protection device is to keep the clamping voltage under the maximum input voltage of the power regulator, or other electronic components in the circuit, without halting or powering down the system. The protection device will not operate until the line voltage reaches 36 V for 1 to 10 minutes or longer, as specified by the vehicle’s manufacturer or as required in withstand test conditions. This means the device does not perform at 36 V in any kind of status in either high or low temperature environments.

App note: Signals with zero offsets

Dealing with zero offsets signals tackled in this app note from Murata. Link here (PDF)

Many transducer outputs exhibit a dc offset voltage when the output level would normally be expected to be zero Volts (corresponding to a display reading of “000”). As an example, consider a pressure transducer whose output levels of 1.0Vdc to 6.0Vdc are required to produce display readings of “000” to “400” respectively. To obtain the desired readings, the 1-6V signal has to be attenuated fi rst, and then its 1V offset voltage must be subtracted or nulled to zero.

App note: Analog common and Reference IN-OUT

App note on Murata’s Digital panel volt meters analog common and reference pins. Link here (PDF)

Perhaps the least understood I/O pin on all DMS Series DPM’s is ANALOG COMMON. The confusion surrounding this pin is not unjustified since it should be left open, i.e., have no external connections, in the vast majority of normal meter applications. It should not be routinely connected to the power supply ground/common, nor should it be connected to a system’s signal (analog) ground/common.
Part of the confusion surrounding this pin arises from the fact that on some older Murata Power Solutions DPM’s, ANALOG COMMON must be connected to the system power supply common/return. This is not true for new DMS Series meters. In particular, never ground this pin on any DMS-20 Series meters or any of the 9V-powered meters in the DMS-30 or DMS-40 Series. Doing so will result in erroneous display readings.

App note: Voltage proof test for metalized film capacitors

App note from Vishay about self recovery of metalized film caps. Link here (PDF)

Voltage proof tests, also called “high pot” tests, are used to check if a capacitor has a breakdown failure mode occurring at a certain test voltage. The detection of breakdown is done by a current detection, specified if exceeding a certain limit (cut off current).
For all capacitor technologies that do not have the ability to recover after a partial breakdown, the current flow is continuous at the moment of a breakdown.
However metalized film capacitors have the property to recover after an instantaneous breakdown (partial breakdown) due to the fact that the metalized electrodes (capacitor plates) act as a fuse. For fusing a small current is needed, but is not continuous.
This effect is defined as “self healing” and not as breakdown.

App note: Secure Key Storage

App note from Silicon Labs on their EFR32 device secure features Key encryption. Link here (PDF)

Secure Key Storage is a feature in Secure Vault-enabled Series 2 devices that allows for the protection of cryptographic keys by key wrapping. User keys are encrypted by the device’s root key for non-volatile storage for later usage. This prevents the need for a key to be stored in plaintext format on the device, preventing attackers from gaining access to the keys through traditional flash-extraction or application attacks, and allowing for a potentially unlimited number of keys to be securely stored in any available storage.

App note: Input for magnetometer placement simulations

App note from Kionix on things to look for and placement evaluation before placing magnetometer on PCBs. Link here (PDF)

Simulations of the magnetic field environment to provide magnetometer part placement recommendations need considerable technical information to assist the process. Magneto-static and magnetic noise information of the materials and magnetic field sources need to be collected from the design candidate’s 3D geometry, materials, and functional proposals. With this information, magneto-static simulations can be done to guide the optimal part placement in a system.

App note: Handheld electronic compass applications using a Kionix MEMS Tri-Axis accelerometer

App note from Kionix on the how to’s of handheld compass, diving into Earth’s magnetic basics, plots and equations. Link here (PDF)

Today’s world is about mobility. The expanded and growing availability of cell phones, PDA’s and GPS has resulted in a massive integration of features into handheld devices. Growing in popularity, the integrated electronic compass is sure to become one of the next standard features.

App note: How to filter the input of a high-side current sensing

App note from STMicroelectronics on high-side current sense RF noise filtering. Link here (PDF)

In an application such as a power supply or a DC-DC converter, the voltage output is generally noisy. Some spikes load the current. Alternatively, a temporary over voltage might occur creating either common mode or differential noise. Such high frequency signals may be demodulated by the current sensing device, resulting in an error in the current measurement.
Consequently, for power supply and DC-DC converter applications, it is necessary to filter the input path of the current sensing to improve the accuracy of the measurement. Such filters must be successfully implemented by choosing the right component values. If the wrong component values are selected, non-desired offset voltages and gain errors might be introduced, which compromise circuit performance.

App note: New family of 150V power schottky

App note from STMircoelectronics on the advantage of power schottky over bipolar diode in SMPS. Link here (PDF)

Nowadays, the Switch Mode Power Supply (SMPS) is becoming more widespread as a result of computer, telecom and consumer applications. The constant increase in services (more peripherals) and performance, which offers us these applications, tends to move conversion systems towards higher output power.
In addition to these developments dictated by the market, SMPS manufacturers are in competition, their battlefield being the criteria of power density, efficiency, reliability and cost, this last being factor very critical.
Today, SMPS designers of 12V-24V output have practically the choice between a 100V Schottky or a 200V bipolar diode. The availability of an intermediate voltage has become necessary to gain in design optimization.

App note: Generating negative output voltage from positive input voltage using MAX17291 boost converter IC with active discharge feature

App note from Maxim Integrated about their MAX17291 generating negative voltage from positive input. Link here

Many applications require the power supply to provide a negative voltage, such as LCD displays, gate drivers, embedded applications, op-amp circuits, etc,. This application note explains how to generate a negative output voltage from a positive input voltage using the MAX17291 boost converter IC.
The MAX17291 is a low quiescent current boost (step-up) DC-DC converter with a 1A peak inductor current limit and True Shutdown™. True Shutdown disconnects the output from the input with no forward or reverse current. The output voltage is set with an external resistor-divider. The MAX17291 IC can operate from 1.8V to 5.5V input supply and can output up to 20V.

App note: External programmable current limit for MAX38902 LDO

App note from Maxim Integrated about adding additional current limiting circuit for their MAX38902 LDO. Link here

Current limit in a LDO establishes an upper threshold for the current delivered. In a low dropout linear regulator architecture, the input and output average currents, which are connected by a series pass-through transistor, are almost the same.

Why current limit? Any surge in the current demanded by the load and/or triggered by a load fault condition results in an additional input current draw. If the device is not over current limited then this additional current can result in unacceptable system performance like increased load ripple, output voltage going out of regulation and, if not limited, can lead to system failure as well. Hence, there is a need to limit the current against these conditions in the interest of safeguarding the associated electronics within and outside the LDO so that it gracefully handles the fault condition (like output short circuit) and auto-recovers when the fault is removed.