App note: SOLERIQ® L38

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OSRAM’s filament looking LED application note. Link here (PDF)

SOLERIQ® L38 (GW T3LxF1) is a filament LED with a beam angle of 360deg for indoor retrofit lighting applications. It combines the advantages of modern LED technology with the aesthetics of traditional light bulbs.

The construction of the SOLERIQ® L38 consists of a ceramic based frame with two alloy connectors at both ends. A number of highly efficient LED chips (depending on the lumen package) is mounted on the ceramic based frame and they are electrically connected through wire bonding, covered by a colored diffused silicone resin.

App note: Magnetometer placement in mobile devices

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Correct magnetometer placement app note from Kionix. Link here (PDF)

Electronic devices contain many parts which can affect a magnetic sensor. When deciding the mounting position, it is necessary to consider the types of materials and the amount of current carried in proximity of the magnetic sensor.

Accuracy of an electronic compass depends upon getting clean geomagnetic data from the magnetic sensor output without errors caused by other magnetic elements. These errors need to be canceled by calibration or correction. This document explains magnetometer integration challenges from the mobile equipment point of view, and gives guidelines for the mounting position of the magnetic sensor.

App note: Embedded orientation detection using the MMA8450Q

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NXP’s accelerometer chip MMA8450Q, provides orientation detection on handheld devices. Link here (PDF)

This application note targets the portrait/landscape orientation detection feature which has become standard in many hand-held electronic devices. Additionally, this application note aims to explain uses as well as highlight some of the challenges of designing an embedded algorithm into the sensor. Included in content, the embedded settings of the MMA8450Q are explained and detailed for implementation.

App note: Practical considerations of Trench MOSFET stability when operating in linear mode

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Practical considerations of Trench MOSFET stability when operating in linear mode, application note (PDF!) from Fairchild Semiconductor

This application note focuses on the factors affecting the thermal instability condition of a trench MOSFET device in Linear Mode. In particular, it studies the phenomenon when the drain current (Id) focusing process occurs that leads to a localized hot spot to the device. Several devices were tested to failure to determine the degree of damage within the die and to differentiate the failure signatures under diferent test conditions. The practical analysis of the device Forward-Biased Safe Operating Area (FBSOA) performance in Linear Mode is presented. It is evaluated in terms of finding the Zero Temparature Coefficient (ZTC) value of the device based on its Id vs. Vgs performance characteristic curves.

App note: Understanding linear resonant actuator characteristics

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Application note about Linear Resonant Actuators from Precision Microdrives. Link here

Linear Resonant Actuators (LRAs) are becoming more popular for haptic applications. They are an alternative to eccentric rotating mass vibration motors and have several distinct advantages. For example they have better haptic performance characteristics and are more efficient. For these reasons they are used in many handheld and touchscreen devices, amongst other applications.

App note: Between the Amplifier and the ADC – Managing filter loss in communications systems

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An application note (PDF!) from TI on optimizing the filter design to minimize the losses:

Filtering plays an essential part in nearly all communications systems. Removing unwanted signals is part of system design to eliminate unwanted noise or distortion. The signal presented to the analog to digital converter should have no spurs or distortion products, especially outside the desired Nyquist band. Noise and distortion spurs that may be safely outside the band of interest may not remain outside of that band after the ADC sampling process folds them around the sampling frequency.
The primary targets for the final analog filter are broadband noise and harmonic distortion spurs. Broadband noise, in particular, can be problematic since the bandwidth of many ADCs is typically several times the bandwidth of the signals to be processed. Likewise, harmonic spurs from the upper end of the band of interest are typically still within the input bandwidth of the ADC, even though they are far removed from the signal band. If not filtered out these spurs and noise can fold back onto weaker desired signals
and mask them.

App note: Implementing an I2C reset

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Interesting app note from Analog Devices when an I2C communication is broken under some circumstances. Link here (PDF)

The I2C bus is a high integrity, robust serial bus used for control purposes in many systems. The primary components that make up a system are at least one master and one slave. Under normal conditions, everything works fine; however, it is the abnormal conditions that generate problems. Two questions present themselves when a problem arises: Is the problem device or system related, or some combination of both? What, if anything, can be done about it?

Hard device failures are relatively easy to isolate. Perhaps a function does not work, proper power cycling does not resolve the issue, pins are stuck high or low, and so on. System related problems sometimes disguise themselves as device failures, or worse, are intermittent. It is the latter area that this application note examines because it represents the majority of bus fault conditions.

Frequently the master, which is usually a microcontroller or a gate array, will be interrupted in the middle of its communication with an I2C slave and, upon return, find a stuck bus. Initially this looks like a device problem, but it is not. The slave is still waiting to send the remainder of the data requested by the master. The problem is that the master has forgotten where it was when it was interrupted or reset.

App note: Environmental compensation on the AD7142: The effects of temperature and humidity on capacitance sensors

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An old but useful application from Analog Devices about things that can affect touch/capacitance sensors. Link here (PDF)

Capacitance sensing has the potential to replace current user input mechanisms in consumer devices. Products as diverse as cell phones, digital cameras, MP3 players, and other portable media players are all suitable for implementing capacitance sensing.

Capacitance sensing has many benefits. It gives the user an interface with greater sensitivity and control. Capacitance sensors are easy to manufacture and reliable, and have advantages over current mechanical interfaces. However, all types of capacitance sensors are affected by capacitance changes in the surrounding environment. Changes in humidity or temperature can interfere with the operation of the sensors, in some cases stopping the sensor from working altogether.