App note: MUX-friendly precision operational amplifiers


Another App note from Texas Instruments on op-amp input safety from breakdown voltages during source switch-over. Link here (PDF)

Multiplexing is a frequently used technique to perform data acquisition in multichannel systems with minimal signal-chain requirements. In this context, the role of the multiplexer (MUX) in an acquisition system is to switch between channels, and send each signal as quickly as possible to a single data converter, thus maximizing system throughput and minimizing delay. To provide accurate processing, a precision amplifier is placed downstream from the multiplexer to precisely drive the analog-to-digital converter (ADC).

App note: Precision current measurements on high-voltage powersupply rails


Two methods for measuring current and what sense amplifier used are tackled in this app note from Texas Instruments. Link here (PDF)

Current is a signal that can provide valuable insight into how a system is operating. Under defined conditions, the amount of current required to perform a task is consistent, making the current information a useful indicator to determine if the system is operating within expectations. There are multiple measurement methods and locations where current is measured to evaluate this informative signal.

App note: IC temperature sensor accuracy compensation with a PIC microcontroller

IC temperature sensor accuracy compensation with a PIC microcontroller

This application note is based on the analog output MCP9700/MCP9701 and serial output MCP9800 temperature sensors. Link (PDF)  here

Microchip Technology Inc. provides a number of analog and serial output Integrated Circuit (IC) temperature sensors. Typically, these sensors are accurate at room temperature within one degree Celsius (±1°C). However, at hot or cold temperature extremes, the accuracy decreases nonlinearly. Normally, that nonlinearity has a parabolic shape.

App note: Parallel crystal circuit input voltage control

Parallel Crystal Circuit Input Voltage Control

This application note is intended for use with all SMSC LAN products incorporating a parallel crystal circuit. The information contained in this application note provides one option to control the voltage across the input of the crystal circuitry. Link here

The designer should incorporate the series resistor shown below in his design to guarantee that the specified device maximum input voltage levels are not exceeded. It is the responsibility of the designer to ensure that all input voltages in his entire design do not exceed the recommended voltage levels in the applicable data sheet. It is strongly recommended to utilize all design suggestions from SMSC and then verify the operation of the circuit in a lab environment. Verification includes measuring all input waveforms with an oscilloscope to ensure proper voltage levels.

13.8V 5A power supply


Dilshan Jayakody published a new build:

13.8V power supplies are commonly used in armature radio experiments. Most of the portable armature radio transceivers are designed to work with a 13.8V power source. We mainly build this power supply unit to power some of our armature radio circuits and modules.
This design is based on the popular LM338 5A voltage regulator. We choose this regulator because of to it’s higher current rating, short-circuit protection feature and higher availability.

See the full post on his blog.

Weather station project


Alvaro Prieto has been working on a wireless weather station project:

After playing around with the breakout boards, I decided it was time to integrate it all in a single board. I named it Chaac.
This is where I ran into issues with MBED. Making the board support package (BSP) for a custom board was not trivial. Another issue was that I couldn’t get the low-power modes working quite right. At the same time, I decided to ditch GPS, since the weather station is unlikely to move without my knowledge . With the new requirements, I ended up switching to an STM32L432KC based board.

See the full post on his blog.

App note: Thermal consideration of flash LEDs


Pulsed LED application like flash LEDs requires adequate thermal management to counter the heavy heat caused by larger current, here’s an app note from OSRAM discussing on thermal management of LEDs. Link here (PDF)

This application note focuses on how to develop an adequate thermal management for LEDs in camera flash applications. It provides information on critical factors and the thermal properties of LEDs during a range of operation modes as well as information on how to develop an adequate thermal management in flashlight applications.

App note: Dimming InGaN LEDs


App note from OSRAM on InGaN LEDs dimming method without penalty on its wavelength. Link here (PDF)

While the InGaN technology produces the brightest light output across Blue, Deep blue, Verde, True green and White, it is important to understand that the wavelength of the light emitted depends on the forward current. In order to avoid shifts in the color, the dimming strategy must be considered carefully.

ATtiny13 – 8bit mono class D amplifier


Łukasz Podkalicki shared a how-to on building a Class D amplifier on ATtiny13:

I always wonder whether it is possible to make an amplifier of class D on ATtiny13 or not. Some time ago I found George Gardner’s project based on ATtiny85 – TinyD. It was a sign to start challenging it with ATtiny13. It took me a few hours but finally I made it! The code is very short and useses a lot of hardware settings which has been explained line-by-line in the comments. The project runs on ATtiny13 with maximum internal clock source (9.6MHz). It gave me posibility to use maximum of hardware PWM frequency (Fast PWM mode).

See the full post on his blog.

Check out the video after the break.

Building the ultimate USB power distribution system


Dr. Scott M. Baker published a new build:

My goals include:
1. The ability to switch each device on/off with a rocker or toggle switch
2. Current limiting capability via a fuse or similar device
3. Overvoltage protection
4. Visual indicator (LED) of operational status
5. Multiple independent outlet

See the full post on his blog.

Check out the video after the break.