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DAC7725- Simultaneous Writes

Sean Higgins
Prodigy 50 points
Other Parts Discussed in Thread: DAC7725

DAC7725 uses the term Transparent.  What does Transparent mean relative to how it's used?  Also, can you write to all four channels simultaneously?

  • 0
    TI__Genius 10615 points

    Hi Sean,

    The DAC7725 registers are immediately updated with the input data when the conditions are met. If  you look at line 1 of Table 1.

    When the conditions are met, the output of Channel A will update immediately with the data at the input pins.

    There is a way to update all channels simultaneously.

    Write and not update (LDAC HIGH) all the channels, and then make LDAC LOW. This will update all the channels at the same time.

    Hopefully this was helpful. Please let me know if you have any more questions.

  • 0 in reply to Eugenio Mejia
    Prodigy 50 points
    What does "Transparent" mean ? But isn't selecting A1=L and A0=L only selecting that particular DAC only? Aren't all the others not accessible when A1=L and A0=L? And does your initial response mean that All the DACs will be updated with the same data? Hence the analog outputs will be the same value when the same data is written?
  • 0 in reply to Sean Higgins
    TI__Genius 10615 points

    Sean Higgins said:
    What does "Transparent" mean ?

    It means that the register of the channel selected will update immediately with the data at the input pins.

    If the input register is transparent, it will immediately save the data at the input pins.

    If the DAC register is transparent, it will immediately read the data from the input register and update the output of the DAC.

    Sean Higgins said:
    But isn't selecting A1=L and A0=L only selecting that particular DAC only?

    Only when reading and writing to the input registers. The LDAC pin updates all the DAC registers regardless of the state of A1 and A0.

    Sean Higgins said:
    And does your initial response mean that All the DACs will be updated with the same data?

    I will explain it more in detail. You can actually update all the DACs at the same time, with different outputs.

    1. CS LOW
    2. LDAC HIGH
    3. Write Channel A with data x1
    4. Write Channel B with data x2
    5. Write Channel C with data x3
    6. Write Channel D with data x4
    7. CS HIGH
    8. LDAC LOW

    This will allow you to simultaneously update all the channels with different data.