App note: Battery fuel gauge IC (LC709203F) for 1-Cell Lithium-ion (Li+)


Lithium-ion fuel gauge IC from ON Semiconductors. Link here (PDF)

The LC709203F is an IC that measures the remaining power level of 1-cell lithium-ion (Li+) batteries used for portable
equipment etc.
This product reduces fuel gauge errors with a unique correction technology during measurement of battery temperature and
This technology has inherently high precision without the need for an external sense.

App note: Crystal oscillator basics and crystal selection for rfPICTM and PICmicro devices


The basics of crystals and crystal oscillators application note from Microchip, link here (PDF!)

This Application Note will not make you into an oscillator designer. It will only explain the operation of an oscillator in simplified terms in an effort to convey the concepts that make an oscillator work.
The goal of this Application Note is to assist the product design engineer in selecting the correct crystal and external capacitors required for the rfPICTM or PICmicro® device. In order to do this the designer needs a clear understanding of the interrelationship of the various circuits that make up an oscillator circuit. The product design engineer should also consult with the crystal manufacturer about the needs of their product design.

App note: Snubber capacitors for complete insurance of power semiconductors


An application note from WIMA about snubber capacitors, Link here.

The trend of modern semiconductor technology towards increasingly powerful applications results in the fact that switched currents and voltage levels are continuously increased and that simultaneously the switching speed is also increasing markedly.
The developments in the area of power semiconductors include the component group IGBT (Insulated Gate Bipolar Transistor) or IGBT modules.
The switching capacity with shortest switching times which can be realized using IGBTs necessitates an extremely low-inductance circuit design. Even the low self-inductance of the power bus may induce dangerous voltage overshoots between collector and emitter which may result in the destruction of the valuable power semiconductors.
To protect the components, so-called snubber suppressor circuits are used. The most important component in this respect is a low-inductance pulse capacitor in order to attenuate or cut off peak voltages.

App note: Selection of capacitors for pulse applications


Guidelines from WIMA about selecting capactiors for pulsed conditions. Link here

The maximum permissible AC voltage that can be applied to capacitors in sinusoidal waveform applications, can be determined from the graphs in the respective capacitor ranges.
However, where pulse conditions exists, the following procedure is to be observed to ensure that the correct capacitor rating is selected for a particular duty:
– Rated voltage
– Maximum current
– Dissipation
– Determining the permissible AC voltage and AC current at given frequencies

App note: Measuring a loudspeaker impedance profile using the AD5933


An application note from Analog Devices about AD5933, this provides a low cost substitute to expensive test equipment like signal generators, oscilloscope and voltmeters in getting the speaker’s impedance profile. Link here (PDF)

This application note describes a circuit architecture using the AD5933 that allows the system designer to measure the impedance profile of the loudspeaker and integrate this circuitry into the audio signal chain. This offers many benefits. Upon system power-up, for example, the circuitry provides the ability to measure the impedance profile and thus the acoustic properties of the loudspeaker, enabling direct comparison to a factory calibrated profile stored nearby. Any changes in the impedance profile are detected and further diagnostics are carried out, preventing premature damage.

App note: Choosing the appropriate component from data sheet ratings & characteristics.


Chossing the right power semiconductor for an application, a technical note from IXYS. Link here

This application note is intended to show how to choose the appropriate rating of a power semiconductor component for a known application using the specifications given in the datasheet. The explanations have been kept sufficiently general to be applicable to all common power circuits. However, for the sake of concreteness, they focus on IXYS IGBT modules and discretes respectively with or without diode. Proceeding as described in the following enables the designer to gain all necessary information from the data sheets for the most economic selection of power semiconductors.

App note: Designing for board level electromagnetic compatibility


Designing for board level electromagnetic compatibility application note (PDF!) from NXP:

Electromagnetic interference (EMI) is a major problem in modern electronic circuits. To overcome the interference, the designer has to either remove the source of the interference, or protect the circuit being affected. The ultimate goal is to have the circuit board operating as intended — to achieve electromagnetic compatibility (EMC).
Achieving board level EMC may not be enough. Although the circuit may be working at the board level, but it may be radiating noise to other parts of the system, causing problems at the system level.
Furthermore, EMC at the system or equipment level may have to satisfy certain emission standards, so that the equipment does not affect other equipment or appliances.
Many developed countries have strict EMC standards on electrical equipment and appliances; to meet these, the designer will have to think about EMI suppression — starting from the board level.

App note: Voltage to current conversion


Using Apex Microtechnology’s power op amps for voltage controlled current sources (VCCS’s) application note, Link here (PDF)

Voltage controlled current sources (or VCCS’s) can be useful for applications such as active loads for use in component testing or torque control for motors. Torque control is simplified since torque is a direct function of current in a motor. Current drive in servo loops reduces the phase lag due to motor inductance and simplifies stabilizing of the loop.

App note: Programmable power supplies


Apex Microtechnology’s application note about programmable power supplies. Link here (PDF)

The programmable power supply (PPS) is not only a key element in automated test equipment, but it is also used in fields as diverse as industrial controls, scientific research and vehicular controls. When coupled to a computer, it bridges the gap from the software to the control task at hand. This application note examines the basic operation of the PPS, the multitude of possible configurations and the key accuracy considerations.

App note: Interfacing an I2S device to an MSP430 device


Interfacing an I2S device to an MSP430 device application note (PDF!) from Texas Instruments:

The MSP430 series of microprocessors are fast powerful devices ideally suited for use with the various wireless transceivers offered by Texas Instruments. In streaming audio applications, however, it is desirable that the microprocessor support an audio bus to allow for interconnection to an audio CODEC.
This application note describes how to create an I2S-like bus (left-justified mode) from an SPI bus using a 4-bit counter, a ‘D’ type flip-flop, and a dual inverter gate.