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Original question:

DAC70501: DAC70501

DAC70501: REF_ALARM

Jim McDaid
Prodigy 10 points
Part Number: DAC70501


Hi all,

I have a similar problem. In my case, I'm using the internal reference and VDD is 3V3. The REF-ALARM bit is set as soon as power is applied. There are 4 combinations of REF-DIV and BUFF-GAIN and the alarm condition is triggered by them all. Is there some other condition which will trigger the reference alarm?

Jim

  • 0
    TI__Genius 11850 points

    Hi Jim,

    As the other thread states, the primary register you want to set is the REF-DIV register. Setting this to 1 should ideally turn off the alarm. If it doesn't, there may be other issues going on with the device. It would be helpful to measure the output of the reference pin to determine if it is being divided correctly. I'll take a look at my own device to see if I can replicate your problem.

    Thanks,
    Erin

  • 0 in reply to Erin Bowrie
    TI__Genius 11850 points

    Hi Jim,

    I can confirm on my own device that with VDD = 3.3V, the reference alarm is high when REF-DIV = 0, and low when REF-DIV = 1. The BUFF-GAIN bit does not matter in this case. 

    Also notably, the REF voltage output does not change when dividing down the reference, so we can not debug using the pin. 

    Other situations that could cause the reference alarm to trigger could be an external voltage is being applied that is out of range or fighting with the reference. You should ensure that you are not applying any other voltages to the reference pin.

    Additionally, there's a chance your system is not communicating with the device properly. This is easy to check by turning off the reference and checking the voltage on the pin. If the pin is ground, you are communicating. If the pin is still 2.5V, then there is an issue in communication.

    Thanks,
    Erin

  • 0 in reply to Erin Bowrie
    Prodigy 10 points

    Hi Erin,

    thanks for getting back to me so quickly. Sorry I didn't reply earlier, I was having a lot of trouble trying to log in to TI.

    I wasn't able to disable the internal reference and it turned out to be because my DAC_init wasn't being processed - when I figured out why, I was able to set REF-DIV, the alarm turned off and I got my expected output. My code, my fault, thank you so much for your help.

    Best regards,

    Jim

  • +1 in reply to Jim McDaid
    TI__Genius 11850 points

    Glad you were able to figure it out!

    Thanks,
    Erin