The LTC2645 is a family of quad 12-, 10-, and 8-bit PWM-to-voltage output DACs with an integrated high accuracy, low drift, 10ppm/°C reference in a 16-lead MSOP package. It has rail-to-rail output buffers and is guaranteed monotonic. The LTC2645 measures the period and pulse width of the PWM input signals and updates the voltage output DACs after each corresponding PWM input rising edge. The DAC outputs update and settle to 12-bit accuracy within 8μs typically and are capable of sourcing and sinking up to 5mA (3V) or 10mA (5V), eliminating voltage ripple and replacing slow analog filters and buffer amplifiers.
LTC2645 – Quad 12-/10-/8-Bit PWM to VOUT DACs - [Link]
The MAX5825PMB1 peripheral module provides the necessary hardware to interface the MAX5825 8-channel DAC to any system that utilizes Pmod™-compatible expansion ports configurable for I²C communication. The IC features eight independent 12-bit accurate internally buffered voltage-output DAC channels. The IC also features an internal reference that is selectable between 2.048V, 2.500V, and 4.096V (4.096V reference operation is not supported with a standard 3.3V Pmod-port power supply).
MAX5825PMB1 Peripheral Module Board - [Link]
bogdan @ electrobob.com wanted to know how much heat a heatsink can dissipate so he build a simple setup using a temperature sesnsor and a mcu. He writes:
It’s quite a common problem when building electronics that some components need cooling which is usually done through some sort of heatsink and optional fans. Choosing the right cooling solution can be a difficult task because the real life behavior of the system is hard to predict or model. In my case I have faced the simple question quite a few times: how much heat can a cooling system dissipate? The thermal resistance of a particular heatsink may vary quite a lot depending on the surroundings or it can simply be unknown to start with. The aluminum side wall of an enclosure made me build this thing.
This is why I have made this little device: a thermometer, a transistor and a microcontroller with a simple command line interface. I could have answered my questions in quite a lot of simpler ways, but since I made a simple thermometer not much else is needed to control the transistor when a DAC is available in the microcontroller.
Heatsink Tester - [Link]
Active analog filters can be found in almost every electronic circuit. Audio systems use filters for frequency-band limiting and equalization. Designers of communication systems use filters for tuning specific frequencies and eliminating others. To attenuate high-frequency signals, every data acquisition system has either an anti-aliasing (low-pass) filter before the analog-to-digital converter (ADC) or an anti-imaging (low-pass) filter after the digital-to-analog converter (DAC). This analog filtering can also remove higher-frequency noise superimposed on the signal before it reaches the ADC or after it leaves the DAC. If an input signal to an ADC is beyond half of the converter’s sampling frequency, the magnitude of that signal is converted reliably; but the frequency is modified as it aliases back into the digital output.
Designing active analog filters in minutes - [Link]
Juan has written an article detailing how to use an MSP430 with a DAC7564:
The DAC7564 is a low-power, voltage-output, four-channel, 12-bit digital-to-analog converter (DAC). The device includes a 2.5V, 2ppm/°C internal reference. The device is monotonic, provides very good linearity, and minimizes undesired code-to-code transient voltages (glitch).
Interfacing the DAC7564 to an MSP430 - [Link]
There were a few questions in the forum about generating sine waves on the MCP4725 I2C DAC. To show one way you might accomplish this, an example sketch was added to the Adafruit MCP4725 library. You can set the resolution between 9-bit and 5-bit, depending on your requirements and how much flash space you can spare. 5 and 6-bit output would benefit from a basic filter to smooth the output out, but 7-bits and higher is reasonably smooth, as can be seen in the image above comparing the out from an Agilent function generator (in blue) and the MCP4725 sketch at 8-bit resolution (in yellow).
Sine Wave Example for MCP4725 DAC - [Link]
Since we’ve been busy adding quite a few I2C sensors and breakouts lately, I thought this technical overview of the 2-wire “Inter-Integrated Circuit” bus might be handy. I2C isn’t fast (typically limited to 400kHz in most real-world situations), but it’s convenient since it only requires two pins and more than 120 devices can be connected on the same bus, address space permitting. For low-pin count devices, it can be a real life-saver since you can hook an OLED display, a DAC, a 7-segment display and 16 servo motors up to your Arduino with a measley two pins and some careful coding! The full bus specification is available from NXP in UM10204 – the bus was created by Philips, whose semiconductor branch later became NXP — but the more concise information from Embedded Systems Academy might be easier to digest as a starting point. The FAQ has some very good information in it.
I2C Bus Technical Overview - [Link]
The aim of this project was to build an MP3/WAV player using just a FPGA, some RAM & a stereo DAC. The project consists of a custom 32-bit soft core processor running at just under 60MHz which decodes the MP3 algorithm in software with no hardware acceleration apart from a single cycle Xilinx multiplier unit.
FPGA based MP3/WAV Player - [Link]
In this article I will discuss my own experiences about designing a USB sound card, which is the USBDAC. DAC is an acronym for Digital-to-Analog Converter because in a sound card, digital data representing the sound is converted into analog voltage that moves the speaker cone.
My device is loosely based on the PCM2706 reference design. I will not go through the tecnical details but instead concentrate on my own experiences in the design of the device. This is to keep people not familiar with electronics, as well as newcomers to electronics design, interested. You will see that one working product is the result of many failed prototypes.
Designing a USB sound card - [Link]
If you’re interested in how delta-sigma modulators and ADCs work, you should check out this excellent introduction by Uwe Beis: [via]
When looking for an introduction to delta sigma conversion I found that most explanations were from a very theoretical point of view. It took me a while to understand how Delta Sigma converters really work. So I decided to write this introduction for people who prefer circuit diagrams to reading abstract equations.
To understand what I’m talking about you should at least be familiar with:
– Standard analogue techniques (op-amps, comparators etc.)
– Standard digital techniques (latches, binary codes etc.)
– Standard ADCs and DACs (resolution, speed)
– What a low pass filter is (at least an analogue one)
– The sampling theorem (sample frequency > 2 x input bandwidth, alias effects)
Delta sigma converters are different from other converters. Note that I do not make a difference between analogue-to-digital (ADC) and digital-to-analogue converters (DAC). Both are very similar and what is realized in one of them using analogue signal processing circuitry is implemented in the other one using digital signal processing and vice versa. I will explain the delta sigma technique with the analogue-to-analogue delta sigma converter as the first object.
An Introduction to Delta-Sigma Converters – [Link]