Puzzling behaviour od AD5336

Hi Guys,

I'm driving an AD5336 and my test code steps from 0 to 1023, then repeats until I stop it.

The chip has a 3V3 supply and all of the Vref pins are at 3V0. LDAC and GAIN are both 0V and PD is at 3V3. Outputs are presently not disconnected to preclude any external influence.

The puzzle is that, rather than rising 0V to 3V0 over the count as I expect, it ramps from 0V to 2V5 over the data range 0..~350, then stops rising.

I can see all the data changing as I expect and even if I had bits swapped or stuck, I would not see the steady ramp to 2V5.

I've replaced the chip, but still get the same behaviour.

Can anyone shed any light on this, please?

Thanks.

Message was edited by: Gordon Scott (correction .. strikeout of inadvertant 'not')

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  • Hi Padraic,

    I guess in this case I couldn't see it because 15 and 16 look similar.

    My previous CAD wouldn't allow duplicate pins, which was an irritation.

    This one does allow them, which apparently is also an irritation.

    This was a case of more haste less speed, for the second time on this board.

    Trying desperatly to get this through for a tight deadling and missing the few significant warnings amongst the sea of ignorable ones. Ouch.

    Thanks for your help.

Reply
  • Hi Padraic,

    I guess in this case I couldn't see it because 15 and 16 look similar.

    My previous CAD wouldn't allow duplicate pins, which was an irritation.

    This one does allow them, which apparently is also an irritation.

    This was a case of more haste less speed, for the second time on this board.

    Trying desperatly to get this through for a tight deadling and missing the few significant warnings amongst the sea of ignorable ones. Ouch.

    Thanks for your help.

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