Using a DAC800 as a digital resistor

[jasonbegin]

digital resistor

Hay everyone, I need a digitally controlled resistor. I don't want to use a digital pot because I need parallel interface. I looked around for a sample schematics using a DAC as a digital pot, but I could not find a solution. I think the DAC800 could do the job, but I am clueless on how to set it up as a variable resistor.

 

[laktronics]

dac800 5v

Hi,
What type of signal you have, is it unipolar or bipolar? and what is the range of the voltage swing? the connectin depends on that.

Regards,
Laktronics

 

[jasonbegin]

digital rezistor

I guess it would be unipolar because that would be the way a regular carbon resistor would work. The voltage would be +5. 8-bits would be the range 0-255; I would need a resistance range of 750Ω - 3.5kΩ, and the decimal value 127 would provide 2.1kΩ.

 

[laktronics]

dac800

Hi,
With DAC800 you will get a voltage divider. I was thinking you are looking for an AC signal attenuator with digital selection, that is why I asked you for the voltage swing. If you need to digitally select an attenuated voltage of 5v dc input, it is also possible. But for some reason if you are looking for a variable resistance output, I am afraid it is not possible with DAC800.
Regards,
Laktronics

 

[jasonbegin]

digital selection resistor

Do you have any ideas that might work?

 

[laktronics]

dac800 potmeter

Hi,
Maxim's digital potentiometer seems to be best suited for your application, since they are real resistance dividers.

Regards,
Laktronics