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DAC that uses i2c 10-bit addressing mode?

Jake Hedlund
Prodigy 40 points
Other Parts Discussed in Thread: DAC101C081

Hi, 

I'm looking for a 10-bit DAC that can support 8+ devices on a single bus. The analog outputs must be isolated from each other, so a multi-channel device won't work. 

The end goal is to have 8+ analog outputs on the same digital bus, with all physically and electrically (except the i2c lines) isolated from each other. I would prefer to use i2c, but SPI is also an option. With i2c, most DACs only have 1 or 2 address select pins, supporting up to 4 devices. Is there a DAC that can support more addresses than this using i2c's 10-bit addressing scheme? Or is there a better way to do this?

Thanks for the advice. 

  • 0
    TI__Genius 10615 points
    Hi Jake,

    You can try looking at the DAC101C081. It only has two selectable address pins, but they are both tri-state giving you up to 10 selectable addresses.

    I don't know of any devices that will give you more addresses than this.

    Why does your application require all the channels to be isolated?
  • 0 in reply to Eugenio Mejia
    Prodigy 40 points
    Thanks for the suggestion. I came across that one in my searching, and the only requirement it didn't fulfill was being able to restore it's output to a mid-range value (e.g. 2.5V) on power-up. I didn't specify in the original question, but the output of the DAC is going to be fed into an op-amp to shift/multiply the output to +/-5V. On power-up, the final output after the op-amp stage must start at 0V as reliably as possible.

    I was also looking into bipolar DACs that could output +/-5V natively, but none met the i2c addressing requirement.
  • 0 in reply to Eugenio Mejia
    Prodigy 40 points
    I should say another close candidate is the MCP47FEB11 (ww1.microchip.com/.../20005375A.pdf) which allows the user to program a unique address per device, and has the ability to store any startup value. The only reason this is undesirable is that it's not possible to configure its address externally (e.g. with DIP switches).
  • 0 in reply to Eugenio Mejia
    Prodigy 40 points
    Didn't see your question for me before, sorry.

    We are controlling a set of thrusters where each set of inputs must be isolated from each other. Each motor requires a +12V isolated supply, and an isolated +/-5V control signal to control the speed/direction. We currently have a design that does not work very well and is limited to 5 channels using filtered PWM. Thus, I was hoping to find a solution using DACs to make the system more robust and expandable.

    See some info here: www.tecnadyne.com/.../AN605_DC_Brushless_Motor_Interface.pdf