Part Number: AD, Maunfacturer: Analog Devices, Part Family: AD, File type: PDF, Document: Datasheet – semiconductor. AD Complete DDS With Bit On-chip DAC FEATURES 5 V Power Supply 50 MHz Speed On-Chip COS Look-Up Table On-Chip Bit DAC Serial. frequency modulation can be performed with the AD Full data on the AD is available in the AD datasheet available from Analog Devices and.
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You may want to check out dagasheet rfgenerator project for more modern version of the chip, and using it with AVR microcontroller. Although the chip is designed for RF applications, it makes a good audio frequency sinewave generator, too.
The circuit is quite straightforward. Phase and frequency selector pins are not used in this application, so they are tied to ground. Resistor and capacitor values are dagasheet out of a datasheet schematics. Do filter the AVDD power supply, and keep the analog and digital grounds separated, connect them in single point as close to power supply as possible.
You probably need some magnifying equipment to work with it depending on your eyesight and steadiness of your hand. I just datawheet the result with flatbed scanner at dpi and examined the result.
AD datasheet, Pinout ,application circuits Complete DDS With Bit On-Chip DAC
In datasheey, the best option for prototyping in my opinion is a ‘format conversion’. This is how I usually do it. I soldered the DIP socket on veroboard, then cut a suitable size piece of a board and placed it over the socket. I then stuck a wire into ax9835 through the board, soldered and trimmed the wire.
The end result is a crude DIP package. I then scraped the pads off from where the TTSOP case needed datashwet go, and soldered wires to ‘dip24’ terminals from each of the pins. Finally I soldered power supply decoupling caps directly to the converter board. After you have soldered and visually examined the format converter, measure resistance from each pin against its neighbors to find any possible shorts. All the magic smoke comes instantly out of a chip, and you have to start all over.
Complete DDS With 10-Bit On-Chip DAC
Not to mention a loss of your hard-to-get chip. As you can see, the code is not a rocket science either. At line there is a subroutine to send a bit command word to AD At line is a subroutine that calculates a bit frequency word for a frequency given in variable F.
Lines 20 to 50 contain the initialization code, after that the output frequency is set to Hz, and chip is taken out of a reset which enables the output.
Below are the scope captures of output signal at 30kHz and khz. As you can see, kHz output only has about 11 discrete steps. Although the 30kHz signal shows no such steps, they are still there, but as there are 10 times more ad835 steps, they are also 10 times smaller.
As the prototype was built on the same board with my other experiments, and power supply was not filtered except the decoupling capacitor, output is a bit noisy. Clearly, some sort of low-pass filtering is required to cut down the higher harmonics, and noise.