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Original question:

DAC7760: DAC7760 voltage and current output problem

DAC7760: DAC7760 alarm pin

furkan f
Prodigy 70 points
Part Number: DAC7760

Hi, I'm triying to use dac7760 and alarm pin is always in low state so dac not work. when i try to read status register there is no data come from dac. Is that mean dac was damaged or is there any other thing that alarm pin need to goes high.

  • 0
    TI__Guru 52683 points

    Hi Furkan,

    This could mean many things.  Most likely the device is not fully powered on or is still in the POR state.  You should verify that all the supply pins are valid.  You should also confirm that the SPI command is correctly formatted.

    Thanks,

    Paul

  • 0 in reply to Paul_Frost
    Prodigy 70 points

    Hi Paul,

    Thank you for your answer. DAC supply with 24 V and 5V and there is no problem with supply. I looked SPI signals with logic analyzer and there is also no problem with spi data. For the initial settings I tried these settings. If dac is in POR state. How to fix that problem or do you have any other suggesitons.

     // 0x56 Write reset register
   WriteSingle_DAC7760(0x56, 0x0001);
 // 0x55 Write control register
    WriteSingle_DAC7760(0x55, 0xB001);
 //0x57 configuration register
   WriteSingle_DAC7760(0x57,0x0B00);

     





  • 0 in reply to furkan f
    TI__Guru 52683 points

    Hi Furkan,

    Is the alarm pin set by immediately at startup? If readback functionally is not possible, then I believe the device is not fully powered and is in an error state.

    Thanks,
    Paul

  • 0 in reply to Paul_Frost
    Prodigy 70 points

    Hi Paul;

    Thank you. I take new DAC7760 now alarm pin give 5v But still DAC not work properly . Output gives 0.5 V always.  I supply 24V  for AVDD  from power supply.  Also 5V for DVDD from stm32. Is that enough for DAC?  Now the main problem is DAC show any response for SPI datas. SPI datas are correct i checked with logic analyzer. If power is enough and DAC is in POR state how do i know that and how to fix that?

  • 0 in reply to furkan f
    TI__Guru 52683 points

    Hi Furkan,

    Can you share the SPI transaction? Can you also monitor the LATCH pin as well? It will be useful to have another engineer look at it.  What is the voltage on the REFIN pin? 

    Assuming everything is connected correctly, the device should be responding.  If it is not responding, then we must assume:

    1. It is not powered on or there is an assembly issue

    2. the SPI is not formatted correctly

    3. the device is damaged

    Thanks,

    Paul

  • 0 in reply to Paul_Frost
    TI__Guru 52683 points

    Any updates?

  • 0 in reply to Paul_Frost
    Prodigy 70 points

    Thank you Paul I solve my problem. The problem was spi connections. Before changed the DAC i changed spi configurations  and After changed chip i was reconfig the spi and it worked. Sorry for my english and late response.