App note: Ambient light sensor SFH5701

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App note from OSRAM on their ALS device SFH5701, its operation and application method. Link here (PDF)

The SFH5701 is a small, two-wire, linear output current ambient light sensor (ALS) with current amplifier and dark current compensation. The ALS is capable of resolving a wide range of ambient light levels (10 mlx – 10 klx) tailored to the spectral response of the human eye and operational from -40 °C to 100 °C.

App note: How to achieve greater accuracy in battery capacity readings for portable designs

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App note from Maxim Integrated on using fuel gauge IC to obtain accurate battery state of charge readings. Link here (PDF)

Because a product’s runtime is limited by battery capacity, it’s critical to have a precise method for measuring the remaining battery capacity to avoid an unexpected shutdown. This application note describes an experiment for obtaining accurate battery capacity readings in a dog-tracking project.

App note: Single-Channel power supply monitor with remote temperature sense

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App note from Linear Technology using their LTC2970 to monitor external temperature aside from doing power management. Link here (PDF)

Many applications with a single power regulator can benefit from the monitoring and control features of a power supply manager, but most power supply manager ICs have more than one channel. In an application that only has one power supply, there will be an unused set of DAC and ADC pins. Instead of letting the unused channel go to waste, we can use these pins, and a bit of microcontroller code, to sense remote temperature.

App note: AMR angle sensors

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Position measurement sensor using magnetoresistive technology discussed in this app note from Analog Devices. Link here (PDF)

Anisotropic magnetoresistive (AMR), thin film materials are becoming increasingly important in today’s position sensing technologies. Magnetoresistive (MR) position measurement has many advantages over traditional technologies. Reliability, accuracy, and overall robustness are the primary factors contributing to the development of MR sensing technologies. Low cost, small relative size, contactless operation, wide temperature range, dust and light insensitivity, and operation over a wide magnetic field range all lead to a robust sensor design.

App note: Overcurrent event detection circuit

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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

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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: Blood pressure monitor fundamentals and design

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Application note from NXP on blood pressure monitor fundamentals using their medical oriented MCUs. Link here (PDF)

Arterial pressure is defined as the hydrostatic pressure exerted by the blood over the arteries as a result of the heart left ventricle contraction. Systolic arterial pressure is the higher blood pressure reached by the arteries during systole (ventricular contraction), and diastolic arterial pressure is the lowest blood pressure reached during diastole (ventricular relaxation). In a healthy young adult at rest, systolic arterial pressure is around 110 mmHg and diastolic arterial pressure is around 70 mmHg.

App note: How to eliminate over stress of MOSFET during start-up of flyback converter

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App note from Richtek about their embedded soft-start function to eliminate MOSFET stress. Link here

Switching Power Supply, compared to Linear Power Supply, is widely used due to its advantages, such as small size, light weight, high efficiency, etc. Flyback Converter, one of the switching power supply topologies, is most suitable for power supply systems that are below 150W because of its unique features of isolation between primary and secondary sides, simple circuit architecture, few components, low cost, etc.

Since switching power MOSFETs play a very important role in switching power supply converters, how to effectively eliminate over-stress of MOSFET during the start-up of flyback converters will be the main focus to be discussed in this application note. The three major aspects to be investigated are flyback controller design, feedback stability, and Snubber design.