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LTC2655 LDAC pin

What happens if the LTC2655 LDAC# pin is tied high (as in the typical application schematic on the last page of the data sheet) ?  The pin description on page 16 doesn't say.  I infer from Table 1 this means I have to use one of the update (or write and update) commands to transfer data from the input register to the DAC register.

If I were to use the LDAC# pin, it updates all 4 DACs from the 4 input registers simultaneously?

What happens if the LDAC# pin is tied low?  Data sheet is even more vague about this condition.

  • Hi, 

    Let me answer your questions. 

    What happens if the LTC2655 LDAC# pin is tied high (as in the typical application schematic on the last page of the data sheet) ?  The pin description on page 16 doesn't say.  I infer from Table 1 this means I have to use one of the update (or write and update) commands to transfer data from the input register to the DAC register.

    With the LDAC pin tied high, you can't update the DAC output via hardware/pin. You are correct that the update or write and update commands could be used. 

    If I were to use the LDAC# pin, it updates all 4 DACs from the 4 input registers simultaneously?

    Yes this is correct. Whatever data is on the input registers will be reflected to the output. Initial input register data should be 0x0000

    What happens if the LDAC# pin is tied low?  Data sheet is even more vague about this condition.

    I couldnt find it in the too. I apologize. It should work as automatically updating the outputs when you send a write command to the input register.

    ~ian