App note: Simplify home audio systems With the PCM9211 – A versatile audio interface transceiver

an_ti_sbaa300a

A digital interface PCM9211 from Texas Instruments app note. Link here (PDF)

Large-screen HDTVs are selling in huge volumes over last few years, primarily driven by amazing improvements in picture quality & form factor (thinner screens). The form factor constraints from having skinny screens result in tiny built-in speakers that are undersized, under-powered and are typically aimed at wrong direction. Hence sound bars have exploded in popularity as complementary audio system by providing a sound experience that more closely matches the TV’s life-like pictures. In addition, with release of HDMI 2.1 specification we finally have a nocompromise audio solution for HDMI as part of the eARC [enhanced Audio Return Channel]. This tech note reviews eARC and simplified Sound Bar design using PCM9211 and how to interface eARC signals with PCM9211.

App note: Overcurrent event detection circuit

an_ti_sboa297

Sample overcurrent detection circuit from Texas Instruments. Link here (PDF)

This is a unidirectional current sensing solution generally referred to as overcurrent protection (OCP) that can provide an overcurrent alert signal to shut off a system for a threshold current and re-engage the system once the output drops below a desired voltage lower than the overcurrent output threshold voltage.

App note: Active filtering in automotive audio applications

an_ti_sboa319

App note from Texas Instruments on isolating DC and high frequency noise in audio using their automotive op amps. Link here (PDF)

Phone calls, emergency alerts, and music are just a few of the reasons that a high quality audio system is vital in automotive infotainment and clusters. Operational amplifiers (op amps) are one of the most common building blocks of automotive audio circuits. Many designers choose to incorporate op amps into their automotive audio circuits in order to increase audio performance. Higher order filters, which can be created through a combination of second order filters, attenuate noise more aggressively than lower order filters. Additionally, active filters remove the chance of unwanted interference with the audio signal.

App note: Capacitive sensing: Direct vs remote liquid-level sensing performance analysis

an_ti_snoa935a

Capacitive liquid level sensing method comparison discussed in this app note from Texas Instruments. Link here (PDF)

Capacitive-based liquid level sensing is making its way into the consumer, industrial, and automotive markets due to its system sensitivity, flexibility, and low cost. With using TI’s capacitive sensing technology, the system flexibility allows designers to have the choice of placing the sensors directly on the container (direct sensing) or in close proximity to the container (remote sensing). Each configuration has its own advantages and disadvantages. This application note highlights the system differences and performance of direct and remote sensing to provide guidance in how capacitive-based liquid-level sensing is affected.

App note: How to select an ambient light sensor for your end equipment

an_ti_sbea006

Another application note from Texas Instruments about ambient light sensors and how to effectively use them. Link here (PDF)

Generally, when someone thinks of trying to design a system with an ambient light sensor there are four main concerns or problems that need to be addressed. The most important features of an ambient light sensor are spectral response, power, size, and range of lux measurement.

App note: How to isolate signal and power in isolated CAN systems

an_ti_slla386

CAN system isolation app note from Texas Instruments, Link here (PDF)

With the increase in the usage of signal isolation in many industrial and automotive applications, the need for isolated power has also increased. The benefits of isolation are lost if the power supplies on either side of the isolation barrier are simply shorted. At the same time, if the isolated power sub-systems are not designed carefully, it affects the overall system performance like temperature rise due to poor power transfer efficiency, data corruption due to emissions, and so on. To simplify the design process of isolated CAN sub-systems, this document provides various options (discrete and integrated) to isolate CAN signals and power.

App note: Detecting selfie sticks using TI audio jack switches TS3A227E and TS3A225E

an_ti_scda014

Old app note from Texas Instruments on smart phone selfie sticks button detection. Link here (PDF)

Selfie sticks are becoming as common of a smart phone accessory as a pair of headphones. Because of the selfie stick’s increasing popularity, smart phone manufacturers need to be able to accommodate the accessory. This report describes the procedure required for a smart phone to detect when a selfie stick accessory is inserted into a smart phone’s audio jack receptacle using TI audio jack switches TS3A227E and TS3A225E. It shows how these devices respond to common selfie-stick implementations and how to adjust the audio jack switch’s register settings to accommodate both traditional audio accessories as well as the new selfie stick accessory.

App note: EMI-hardened operational amplifiers reduce inaccuracies

an_ti_sbot041

EMI reduction built-in on op amps, app note from Texas Instruments. Link here (PDF)

Operational amplifiers (op amps) with electromagnetic interference (EMI) filters can reduce significant errors. These types of errors are not always obvious to the system designers. They often impact the signal chain, in particular the analog-to-digital converter in the form of a loss of digital counts.

App note: How to properly configure unused operational amplifiers

an_ti_sboa204

Good read app note from Texas Instruments about configuring unused op amps on multi amp chips. Link here (PDF)

Multi-channel operational amplifiers (op amps) are often implemented in circuits that do not require the use of all channels. Undesired behavior in an unused amplifier channel can negatively impact system performance, as well as the performance of the channels in use. To avoid degradation of both the op amp and system performance, the unused op amp channels must be configured properly.

App note: Current sense amplifiers in class-D audio subsystems

an_ti_slva031

App note from Texas Instruments about output current sensing in class-D amplfiers. Link here (PDF)

Current sensing in audio subsystems are widely used in conjunction with CLASS-D amplifiers for diagnostics or to provide speaker current feedback to the DSP for speaker enhancement to emulate smartamp. The most expensive component in the audio subsystem is the speaker. The impedance of the speakers ranges from 2Ω for subwoofer to a 8Ω for stereo speakers. Exceeding the current flowing through the speakers has a potential to create excessive heat in the voice coil which can lead to permanent damage of the speakers.