App note: Multiplex boosted class-D without additional external circuitry

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An analog switch MAX14689 from MAXIM Integrated let signals that are higher than rail voltage pass. Link here (PDF)

Boosted class-D amplifiers drive speakers with voltages greater than the supply voltage. These amplifiers are becoming more common because they allow higher performance audio from a single lithium ion battery. Most boosted class-D amplifiers, however, do not give the user access to the internal boosted voltage. This makes it difficult to multiplex a speaker to multiple audio sources using common analog switches. This application note discusses how the Beyond-the-Rails capability of the MAX14689 allows it to switch these signals without additional circuitry.

App note: HT45F3420 LED flashlight application

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Holtek’s HT45F3420 MCU provide LED flashlight application all in with minimal external components. Link here (PDF)

In traditional LED flashlight application circuits, the battery is used to directly drive the LED which will cause uneven brightness levels and the possibility of damaged LEDs due to changing battery conditions. Using the HT45F3420 for LED flash application, both buck and constant current techniques are used.

App note: BH45F0031 Earphone jack communication

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Holtek’s App note about their audio to digital signal converter chip BH45F0031 that together with an phone app, communication via audio phone jack is possible. Link here (PDF)

The BH45F0031 is a Flash type 8-bit high performance RISC architecture microcontroller, which is designed for smart phone headset interface applications that can directly transmit data and communicate with the microcontroller using their audio earphone interface.

The BH45F0031 can convert the analog audio signals from mobile phones into digital data and transmit them to a master external MCU. The device can also convert the digital data from the master MCU into analog audio signals and transmit them to mobile phones.

App note: Improve flicker performance of direct AC driven LED fixtures with self valley fill

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Application note from ON Semiconductors on LED lighting flicker caused by its own AC supply by adding an improved self valley fill circuit. Link here (PDF)

To provide power to LED loads from AC input, SwitchMode Power Supplies (SMPS) are generally used since LED need to be driven by regulated current. Consequently, LED lighting solution have to inherit the design complexity of a typical SMPS which includes designing the magnetic component, handling of Electromagnetic Interferences (EMI) as well as implementing Power Factor Correction (PFC). Direct-AC Drivers (DACD) for LEDs provides a new way to drive the LED load from an AC input with much simpler system architecture while satisfying EMI and power factor (PF) requirements with minimal effort. However, its drawback is flickering of light output at the zero crossing of AC line voltage due to loss of current to the LED load.

Though flicker is not always obvious, it can still cause headaches for a small percentage of people exposed to flickering lights for long periods. This is a major issue for offices, schools, stores and other brightly lit commercial and industrial spaces where people spend a lot of time.

App note: Using touch interface in harsh environments

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Tough design and software reference from NXP of touch interface. Link here (PDF)

The touch-sensing method is used to replace most of traditional tact switch inputs as a new type of human-machine interface used in home-appliance applications. However, using such kind of detection method in harsh environment is still a challenge for most of product designers. A good balance of fast response and no false trigger in key detection is always an essential factor for the user-interface design. The touch-sensing input (TSI) module in Freescale MCUs provides capacitive touch detection with high sensitivity and durability, which can help customers to adapt this kind of human touch-sensing technology quicker.

This application note describes how to use the S08PT family MCU features in applications with emphasis on both touch-sensing interface and safety aspect. Different techniques in circuit design, intelligent software control and reliable mechanical structure are illustrated in this application note to show how to achieve a product design with protection features for handling faults and fast TSI response without any false trigger in extreme conditions. Most of the critical scenarios and unexpected use cases from the end-user point of view must be fully studied and well-covered in advance to prevent any serious flaw persisting in the final design stage which causes significant delay in the whole project schedule.

App note: Water level monitoring

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A reference design from NXP about water level detection using pressure sensor. Link here (PDF)

Many washing machines currently in production use a mechanical sensor for water level detection. Mechanical sensors work with discrete trip points enabling water level detection only at those points. The purpose for this reference design is to allow the user to evaluate a pressure sensor for not only water level sensing to replace a mechanical switch, but also for water flow measurement, leak detection, and other solutions for smart appliances. This system continuously monitors water level and water flow using the temperature compensated MPXM2010GS pressure sensor in the low cost MPAK package, a dual op-amp, and the MC68HC908QT4, eight-pin microcontroller.

 

App note: Choose the right voltage regulator to extend battery life in wearables

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App note from Maxim Integrated on wearable devices demanding reduced quiescent and shut down currents when in idle and in sleep mode in a voltage regulator. Link here

Wearable devices have emerged as the next big market opportunity in the electronics industry. Smart watches are among the most popular wearable items today. The healthcare market, including the medical, fitness and wellness sectors, promises even broader opportunities. The majority of wearable gadgets have a number of things in common.

Wearable devices must:
– Be always ready for use
– Be small and lightweight in order to be easy to wear
– Last a sufficiently long time on a re-charge or on a disposable battery
– Support short periods of activity, spending the majority of time in idle or sleep mode
– Last a very long time in idle or sleep mode

App note: Voltage reference long-term stability reduces industrial process control calibration costs

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Application note from Maxim Integrated about improved long term stability of their voltage references. Link here (PDF)

Large industrial plants such as those in the oil, gas, electricity, pharmaceutical, and food and beverage industries rely on electronic instrumentation to provide accurate, stable measurements to control their processes. The stability of an instrument very much depends on its application and the environment in which it operates. Fluctuating temperatures, harsh manufacturing conditions, humidity and elapsed time are all factors that affect stability.

App note: Designing reliable drones using proper circuit protection

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Littelfuse’s application note on drone circuitry protection, offering guard against overcharging its batteries, I/O and ESD protection. Link here (PDF)

No doubt “pilot losing control” is behind many drone incidents and crashes. But what’s behind that “loss of control?” After all, even small recreational drones depend on a host of subsystems – GPS, receiver antennae, WiFi I/O ports and electronic speed controllers – to stay in the air. Lose one and that UAV becomes a UFO pretty quickly.

The number of consumer, professional, and commercial drones, sometimes called unmanned aircraft systems (UASs) or unmanned aerial vehicles (UAVs), sold annually has risen rapidly over the last few years. Future sales growth looks even more rapid, with the Federal Aviation Administration predicting that sales will grow from roughly 2.5 million this year to 7 million by 2020, with 4.3 million being sold to hobbyists and 2.7 million units being sold for professional and commercial applications. Non-military drones are available at a wide range of price points, anywhere from toys that cost less than $100 to sophisticated commercial drones for use in fields like aerial photography, public safety services, agriculture, and wildlife management that can cost thousands

Regardless of how a particular drone is used or how much it costs, all drones are susceptible to similar fault and failure conditions. These conditions can cause problems that range from the merely annoying (a drone that won’t start or take flight) to the catastrophic (a crash that causes major property damage or personal injury). A battery that catches fire during charging or a mid-flight failure due to any of a number of electrical issues are common examples that highlight why robust electrical protection is essential. Fortunately, a growing array of tools and techniques are available to implement passive battery safety systems, electrostatic discharge (ESD) protection, and stalled motor protection.