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DAC8562: confused about LDAC function

Part Number: DAC8562


  According to DATASHEET. I plan to design a application for my project.

  After Power UP, I configure DAC: 1.LDAC pin active for DAC-B and DAC-A    2. Enable internal reference and reset DACs to gain = 2.

           After the configuration registers were done, I start to SEND out samples to each channel for the DAC.

            My plan is that : 1.first send out samples for channel A. (Command = 000, Address = 000.)   2.then send out samples for channel B.  (Command = 000, Address = 001.) 

                                      3.Finally, send out a Low pulse for LDAC pin. 

                                          The DAC genereted the desired analog signal as expected.

  But I also carry out a test: 1.first send out samples for channel  A (Command = 000, Address = 000.)  2.then send out samples for channel B.  (Command = 000, Address = 001.) 3 .Never send out a low pulse for LDAC pin ,LDAC pin keep high level .

  It is a big surprise that the DAC can also genereted the desired analog signal .

  In my opinion , LDAC never update DAC  and DAC will keep still on a known level.


 Is there any wrong about my knowledge on DAC8562?  Or there is a misunderstand  on the datasheet?

  • Hi Ng,

    Before answering the question, I am assuming you are operating device in asynchronous mode.

    Now, first mode of operation what you described as perfect LDAC functionality.

    Coming back to second, before doing this test, did you do power cycle for the device? or just repeated those sequence in the first with different data being sent to DAC A & B? if its just send different data, you are not going to get updated DAC output unless you bring LDAC low.

    Unless you bring LDAC pin low, you will never get updated DAC output in asynchronous mode.

    Your commands are fine first 000, address, Data for asynchronous mode of operation. Honestly I am bit surprised to see you can still get updated DAC value with LDAC not being brought low

    Did you send different data or same data as first? if you send same data, we cannot really say. Can you try sending all 0's first and bring LDAC low, and then send all 1's ?