+ Post New Thread
Results 1 to 6 of 6
  1. #1
    Member level 3
    Points: 1,102, Level: 7

    Join Date
    Sep 2014
    Location
    Prague
    Posts
    60
    Helped
    2 / 2
    Points
    1,102
    Level
    7

    How to choose available ADC/DAC pair, so they can be directly connected?

    Hello,
    i am looking for "complementary pair" of ADC and DAC. How can i be sure that they will work together before buying and testing their cooperation?

    For example i am looking at AD5611 --> AD7477

    I want to put analog signal into ADC and then have (almost) identical analog signal at the output of DAC. But datasheets do not say a word about reccomended pair or compatibility between ADCs and DACs.

    All i can get is info about available interface (SPI, I2C,...)
    I suppose that not all SPI chips are compatible as they can send data in different formats (or data types). Same goes for I2C and other interfaces.

    So what is right way to be sure ADC and DAC will play together well? I suppose that bit resolution of both has to match. and DAC should handle at least same speed as ADC (or more). Will these chips cooperate between brands? Is there some general rule to look at ADC/DAC pair and tell if they will cooperate without intermediate mcu or not?


    I want to make "analog" isolator using digital isolator between ADC and DAC. And i've read that SPI is better choice than I2C. Is that true? I hope that single simple optocoupler will do the trick with SPI... Also i hope that it will be possible to upgrade to more expensive ADC/DAC pair (with higher resolution) without modyfiing isolation circuit if concept will prove working.

    •   AltAdvertisment

        
       

  2. #2
    Full Member level 3
    Points: 1,894, Level: 10

    Join Date
    Oct 2012
    Location
    India
    Posts
    162
    Helped
    36 / 36
    Points
    1,894
    Level
    10

    Re: How to choose available ADC/DAC pair, so they can be directly connected?

    Why not use an amplifier or buffer instead of ADC-DAC pair?



    •   AltAdvertisment

        
       

  3. #3
    Member level 3
    Points: 1,102, Level: 7

    Join Date
    Sep 2014
    Location
    Prague
    Posts
    60
    Helped
    2 / 2
    Points
    1,102
    Level
    7

    Re: How to choose available ADC/DAC pair, so they can be directly connected?

    as i said... i want to use digital isolator on the bus between adc and dac...



    •   AltAdvertisment

        
       

  4. #4
    Super Moderator
    Points: 251,556, Level: 100
    Awards:
    1st Helpful Member

    Join Date
    Jan 2008
    Location
    Bochum, Germany
    Posts
    43,806
    Helped
    13321 / 13321
    Points
    251,556
    Level
    100

    Re: How to choose available ADC/DAC pair, so they can be directly connected?

    ADC/DAC pairs with serial interface, e.g. SPI, can't be never directly connected. They are both slave devices and need to be controlled by a master like a microcontroller or dedicated logic.



  5. #5
    Member level 3
    Points: 1,102, Level: 7

    Join Date
    Sep 2014
    Location
    Prague
    Posts
    60
    Helped
    2 / 2
    Points
    1,102
    Level
    7

    Re: How to choose available ADC/DAC pair, so they can be directly connected?

    So what solution can you reccomend to me? maybe i dont need SPI ADC/DAC. It can be some high frequency PWM (or other) modulator and demodulator which can make signal go through optocoupler safely without feedback...



    •   AltAdvertisment

        
       

  6. #6
    Super Moderator
    Points: 28,512, Level: 41
    andre_teprom's Avatar
    Join Date
    Nov 2006
    Location
    Brazil
    Posts
    8,476
    Helped
    1078 / 1078
    Points
    28,512
    Level
    41
    Blog Entries
    6

    Re: How to choose available ADC/DAC pair, so they can be directly connected?

    There is an option to do that, but not so much elegant. You can use 2 uCīs at each side, one sending end other receiving. The low cost familly CY8C24 allow synthesize a limited number of analog and digital systems inside, and contais a lot of template modules such as A/D, D/A, UART, SPI, etc...

    It is important to know how much speed is required for this application.
    I mean, this conversion is part of a loopback control circuit ?
    --------------------------------------------------------------------------------------------------
    Part of the world that you live in, You are the part that you're giving ( Renaissance )



--[[ ]]--