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DAC7578: Utilization of LDAC funtionality

Sara Lukic
Prodigy 70 points
Part Number: DAC7578

Tool/software:

Hello,

Our costumer is looking to utilize the LDAC functionality for the DAC7578. Are the Data Buffer and Data register the same or they can be programmed differently?

 

Can we load different data in buffer and register, or it will be the same? Or is data from the I2C bus received in the buffer and then loaded into the DAC register?

 

 Thank you

  • 0
    TI__Guru 53993 points

    Hi Sara,

    These are technically different registers.  The DAC7578 features double buffering, meaning there are two registers.  The Data Buffer, or sometimes called the Input register, is writable, but the DAC will only update for the DAC Register.  This double-buffering is useful when you are trying to implement simultaneous updates.  You could update the DAC buffer for a subset of channels each with unit values, then trigger all of those values to latch into the DAC Register simultaneously.  

    Nearly all modern DACs feature some kind of double buffer, though sometimes the DAC Register is unreadable, AKA write-only memory.

  • 0 in reply to Paul_Frost
    TI__Prodigy 70 points

    Hi Paul, Thank zou for the answer

    Does that mean both the registers have same address and can be accessed using the same commands?

  • 0 in reply to Sara Lukic
    TI__Guru 53993 points

    No, it means that there are various commands that handle how you update the DAC.  The different commands are listed in the datasheet, but fundamentally you have a few options:

    1. Write to the input data buffer only, and then later trigger the value from the data buffer to be writing to the DAC Register using an "LDAC" command (latch command).

    2. Write to the input data buffer, but using a command that causes that value to be latched by the DAC Register immediately.  This is sometimes called "transparent mode".

    Thanks,

    Paul