Is it possible for the AD5770R to output voltage from PVDD if voltage is applied to VREF_IO with no power applied to PVDD?

Hi miky 

What are the states of the other power supply pins of the AD5770R when this happens? 

There could be some stray voltages that pass through the protection diodes inside the part. Also it is not recommended to leave power supply pins open and unbiased. This should be considered in the design. If operating the part outside the conditions mentioned in the specification table, then we cannot guarantee the device performance.

In your setup, what happens at the output when you power up the circuit with all power supplies available? The outputs should default to 0mA. 

Best regards,

Ian

Hi,  

Thank you for answering my question.

Is the following caused by having the power supply pins open and unbiased?

The status of the power supply pins is as follows.
I was able to confirm an output voltage of about 1.1V from PVDD.
Output voltage of about 3.3V from AVDD was confirmed.

Condition.
USB is connected to P10 of EVAL-ADICUP3029 and power is supplied to U4 (ADP124ARHZ-3.3-R7).
Vref is externally supplied with 2.5V.
No voltage is supplied to PVDD of EVAL-AD5770R-PMDZ.
Under these conditions, the output current of IDAC0~IDAC5 is 0uA.

Best regards,

miky

Hi,  

Thank you for answering my question.

Is the following caused by having the power supply pins open and unbiased?

The status of the power supply pins is as follows.
I was able to confirm an output voltage of about 1.1V from PVDD.
Output voltage of about 3.3V from AVDD was confirmed.

Condition.
USB is connected to P10 of EVAL-ADICUP3029 and power is supplied to U4 (ADP124ARHZ-3.3-R7).
Vref is externally supplied with 2.5V.
No voltage is supplied to PVDD of EVAL-AD5770R-PMDZ.
Under these conditions, the output current of IDAC0~IDAC5 is 0uA.

Best regards,

miky

Hi miky, 

The EVAL-AD5770R-PMDZ is connecter to EVAL-ADICUP3029 via P1 right (PMOD) If that is the case, then there is also AVDD and IOVDD powered up coming from EVAL-ADICUP3029 board. So the only supply unbiased are PVDDx. 

It could be caused by having them unbiased. I doubt that you'll be able to output any current from that without supplying PVDDx even if you read some voltage on it. And as mentioned, it is not recommended to leave the supply pins unbiased. Please operate at the recommended supply ranges.