App note: LCD screens don’t flicker – or do they?


An old application note from Intersil on comparison of CRT and LCD regarding display flicker. Link here (PDF)

When comparing CRT to LCD screens, one of the most popular differences is the issue of flicker. It is a common assumption that CRT screens flicker while LCD screens do not. In truth, both screens have some amount of flicker. The mechanisms are different and methods for correction have varying amounts of success. This appnote presents the cause of flicker in LCD screens and offers a solution for avoiding flicker by using our ISL45041/2 LCD Module Calibrator in LCD panels.

App note: Interfacing AT84AD001B dual 8-bit 1 Gsps ADC and AVR ATmega128L


e2v’s application note interfacing their 1 Gsps 8-bit ADC to AVR. Link here (PDF)

With its smart feature (3-wire serial interface), e2v’s AT84AD001B dual 8-bit 1 Gsps ADC provides you with digital control over various functions offered with the dual ADC: calibration, gain and offset adjustments, DMUX ratio selection, analog and clock input mode, and partial or full standby mode.

This digital control via the 3-wire serial interface can be managed using Atmel’s ATmega128L AVR. The aim of this application note is to provide you with the relevant information for interfacing these two devices.

App note: Designing VCNL3020 into an application


An app note from Vishay: Designing VCNL3020 into an application (PDF!)

The VCNL3020 is a proximity sensor with I2C interface. It combines an infrared emitter, PIN photodiode, and signal processing IC in a single package with a 16 bit ADC. With a range of up to 20 cm (7.9″), this stand-alone, single component greatly simplifies the use and design-in of a proximity sensor in consumer and industrial applications because no mechanical barriers are required to optically isolate the emitter from the detector. The VCNL3020 features a miniature leadless package (LLP) for surface mounting in a 4.9 mm x 2.3 mm package with a low profile of 0.83 mm designed specifically for the low height
requirements of smart phone, mobile phone, digital camera, and tablet PC applications. Through its standard I2C bus serial digital interface, it allows easy access to a “Proximity Signal” measurement without complex calculations or programming. The programmable interrupt function offers wake-up functionality for the microcontroller when a proximity event occurs which reduces processing overhead by eliminating the need for continuous polling.

App note: WM8731 Suggested power-On/Off sequence


Interesting app note from Cirrus Logic on how to minimize popping sound on the output when turning on/off the DAC on their WM8731 digital to analog converter. Link here (PDF)

As with any consumer audio product, it is important that any on/off power noise be kept to a minimum. Generally, this is done with some sort of external mute circuit at the output socket of the application. Although effective, this does increase the BOM (bill of materials) cost, which in many cases is a critical factor.

With this in mind, the WM8731 DAC signal path may be powered-on in such a way that power on/off noise is kept to a minimum with no need for an external muting circuit, reducing the BOM cost.

App note: CS3001/2/11/12 & CS3003/4/13/14 Chopper-stabilized Operational Amplifiers



Cirrus Logic’s app note, discussing their own designed chopper amps. Link here (PDF)

The chopper-stabilized amplifiers designed at Cirrus Logic are unique. These amplifiers offer performance benefits that combine the best features of bipolar amplifiers with the best features of chopper amplifiers. The intent of this application note is to understand Cirrus Logic’s unique technology and to see how it can be applied in various measurement applications.

App note: Output buffer options for Si53X/55X/57X/59X XO/VCXO devices


SiLabs’ application note: Output buffer options for Si53X/55X/57X/59X XO/VCXO devices (PDF!)

The Si53x/55x/57x/59x XO/VCXO devices can be ordered with one of four different output buffer types: CMOS, LVPECL, LVDS, or CML. Each output type has its own particular benefits and disadvantages. This document describes each buffer type, proper biasing and termination schemes, and related technical trade-offs.

App note: WM9712 Jack plug auto-detection, hookswitch detection and microphone headset detection


App note on Cirrus Logic’s WM9712 jack plug auto-detection by monitoring the connected headphone resistance. Link here (PDF)

This application note describes two operations associated with using headset. The first is the facility to automatically switch between a mono ear speaker and stereo headphones for use in a Smartphone, PDA etc. The second operation is a method which can be used to detect if stereo headphones have been attached or if a mono headset with microphone has been attached.

App note: An Introduction to MEMS Microphone Specifications


An application note from Cirrus Logic on their MEMS microphones, which are small and perfect for wearables devices. Link here (PDF)

MEMS microphones are small form factor microphones, which translate acoustic sound pressure input into an electrical output response. They utilise the silicon wafer processes from the microelectronic industry to create high performance microphones of increasingly smaller geometries.

These processes give MEMS microphones a number of advantages over conventional electret condensing microphones (ECM), which has resulted in a general market transition to MEMS technologies for many of the latest consumer applications, including those requiring multi-microphone support or high quality capture.

The aim of this applications note is to enlighten readers with little or no experience of MEMS microphones to a point that they are confident in basic terminology and able to understand datasheet information to make product selections.

App note: Ultrasonic sensing basics for liquid level sensing, flow sensing, and fluid identification applications


Here’s an app note from Texas Instruments: Ultrasonic sensing basics for liquid level sensing, flow sensing, and fluid identification applications (PDF!)

One of the most effective areas of sensor technology is ultrasonic, the science that measures the time interval between an ultrasonic signal that is sent and received, or what is commonly referred to as “timeof-flight” (TOF). TI is leveraging its ultrasonic expertise to deliver new signal conditioning solutions to fluid level sensing, fluid identification, flow metering, and distance sensing customers with its latest products (TDC1000 and TDC7200) based on time-to-digital converters (TDCs).
This application note provides an introduction to how Texas Instruments Ultrasonic Sensing solutions (TDC1000 and TDC7200) can be applied to popular applications such as liquid level sensing, flow sensing, and fluid identification.

App note: Iris Recognition SFH 4780S


This application note from OSRAM describes the use of the SFH 4780S in iris recognition (iris scanning) as illumination module. Link here (PDF)

Personal authentication is becoming a key requirement for various electronic devices. Besides of the pin number, today most systems are based on so called biometric “properties”. Biometrics can include fingerprints, facial features, retina, iris, voice, fingerprint, palmprints, vein structures, handwritten signatures and hand geometry. All these biometrics have various pros and cons. However, only iris recognition claims to be a ‘hard-to-spoof’ system in combination with an ultra-low false acceptance rate (i.e. one in a million). Additionally, it also features greater speed, simplicity and accuracy compared to other biometric systems. The traits of iris recognition systems rely on the unique patterns of the human iris which are used to identify or verify the identity of an individual.