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Any SPI/I2C programmable voltage reference? — Parallax Forums

Any SPI/I2C programmable voltage reference?

CuriousOneCuriousOne Posts: 931
edited 2013-06-08 13:40 in General Discussion
Hello.

I need a programmable voltage reference, which will able to provide voltage from 0.8v to 3.3v, SPI interface is preferred, but others are also OK. I've tried to look at maxim and analog, no luck, google also gives nothing. There are some DAC based products, but none with that simple management.

Comments

  • kwinnkwinn Posts: 8,697
    edited 2013-06-08 11:20
    There are dozens if not hundreds of dac and adc/dac chips with serial, I2C, clock/data, and SPI interfaces that could be used for this. What resolution do you need?
  • CuriousOneCuriousOne Posts: 931
    edited 2013-06-08 11:28
    Maybe I was incorrect, I need a device which can be programmed via serial interface, and when disconnected from interface, remembers the programmed voltage and outputs it without any further programming/control hardware needed. Have no idea about resolution, but 1 millivolt will be fine I guess.
  • kwinnkwinn Posts: 8,697
    edited 2013-06-08 12:27
    For 1mV resolution between 0V and 3.3V you would need a 12 bit dac. Do a google search for “serial dac 12-bit”. Most of them have a register that can be loaded with the required voltage and with proper design it will maintain that voltage when the serial connection is removed. Of course if power is removed it will need to be reprogrammed, so battery backup would be required if that is a problem.
  • CuriousOneCuriousOne Posts: 931
    edited 2013-06-08 12:38
    Yes, that would be a problem. I'm thinking going another way - using programmable resistor arrays with latch memory, but not sure how their stability is comparable with dedicated reference voltage generators.
  • kwinnkwinn Posts: 8,697
    edited 2013-06-08 13:14
    Yes, if you want to "set it and forget it" through power on and off it is a bit more difficult. Not familiar with, so not sure how stable or accurate programmable resistor arrays with latched memory would be. There are other approaches to doing this such as a parallel eeprom with parallel dac, but that would be fairly costly. A tiny microprocessor with a serial dac might be an option. Program the micro with the voltage setting and firmware so the micro sends the voltage setting to the dac on power up.
  • kwinnkwinn Posts: 8,697
    edited 2013-06-08 13:16
    Might even find a micro with a built in dac.
  • CuriousOneCuriousOne Posts: 931
    edited 2013-06-08 13:25
    So far, best result is Maxim DS4305. Altrough it requires external reference voltage, once applied, it can "remember" it and reproduce without additional hardware, even after power loss.

    http://datasheets.maximintegrated.com/en/ds/DS4305-DS4305K.pdf
  • kwinnkwinn Posts: 8,697
    edited 2013-06-08 13:33
    Take a look at Analog's ADUC814 and TI's MSC1202. There are probably more choices as well. Try googling “microcontrollers with dac”.
  • kwinnkwinn Posts: 8,697
    edited 2013-06-08 13:40
    The DS4302 looks like a good choice even if you have to add a voltage reference, and at $1.02 (qty 1) from Mouser the price is right.
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