What about R-2R network and shift register for DAC

I've read online about the R-2R resistor network as digital to analog converter. http://en.wikipedia.org/wiki/R-2R#R-2R_resistor_ladder_network

I'm contemplating about this way to construct an 8-bit converter with a shift register to do "real" digital to analog conversion instead of using the PWM. Any suggestions? Thanks. ::)

be sure to use high tolerance resistors

You don’t need high tolerance for an R-2R ladder, you just need the values to be as close to the ratio as possible. This comes with high tolerance resistors but it is not a necessity.

Thanks guys. I want to output smoother signals than what PWM can do. Say suddenly going from zero to full range is not good for things like a light bulb, but should be ok with an LED and I'm dealing with light bulb-like stuff.

I tried to find an R-2R network ic on digikey and couldn't find one. Do they come in an ic package or do I have to make the network with discrete elements?

Thank you Richard ;D. I want to make things compact and don’t like to solder much. The output of the ladder will drive an analog power supply by the way. Oh, I got an idea to increase the accuracy of DAC by oversampling. I’ll give it a try. Like outputing 4.1V 50% time and 4.0V 50% of time to get 4.05V. Hope I’m right. ::slight_smile: