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DAC60501: No Output

Gordon McKenzie
Intellectual 610 points
Part Number: DAC60501

Hello,

I'm trying to bring up a circuit that includes a DAC60501M and I'm finding I get no output whatsoever. Relevant section of schematic below. From what I understand from the datasheet, the default settings should be sufficient to give an output as soon as the POR sequence is complete, and because I'm using the 'M' version it should go to midscale. I therefore expected that as soon as I applied 3V0_COND to the VDD pin, I would see midscale voltage at the output. It doesn't - it just sits at 0V.  It doesn't respond when I try to write the DAC value register either, so I have to assume there's something fundamentally wrong that's preventing me seeing any output at all. It's a weird one as it the circuit design seems simple enough.

Intention is to operate in SPI mode by pulling pin 4 low. Verified that 3V0 is correctly being applied to pin 1 (VDD).

Because it should run in SPI mode, I can't read any registers which is a bit of a pain, but it seems so simple that I'm surprised there's any issue. Have I done something stupid here?

Thanks,

Gordon.

  • +1
    TI__Mastermind 19086 points

    Hi,

    Are you getting 2.5V on pin 8? if no, there is some configuration issue.

    Since your supply is 3V, internal reference has to be set for div by 2 first by writing into Gain register ( write 0x0101), so that REF_DIV bit is se to 1.

    This make sure that reference is divided by 2 and output buffer has a gain of 2 resulting in 0 to Vref as your output.

    Have a look at the datasheet recommendation below regarding this requirements.

    Regards,

    AK

  • 0 in reply to Akhilesh K
    Intellectual 610 points

    Hi Akhilesh,

    thank you for getting back to me so quickly.I did have 2.5V on the VREF pin, so I followed your instruction to write 0x0101 to reg 0x04 and it now seems to be running quite nicely.

    I had read that section of the datasheet a number of times but I hadn't properly realised what it meant. I'm glad it was a simple thing!

    Thanks for your help, much appreciated.

    Gordon.