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DAC8771: External loop power source

May
Genius 9880 points
Part Number: DAC8771

Hi, 

Customer want to confirm the following regarding DAC8771, please see details below.

Is it possible to feed the DAC8771 from an external loop power source?

In the datasheet:

"The DAC8771 can also be operated without using the integrated Buck-Boost converter. In this mode, pins PVDD,AVDD, and VPOS_IN must be tied together and driven by the same power supply (12 V to 33 V). In this mode in order to reduce output transients it is recommended that DVDD is applied first, followed by VPOS_IN / PVDD /AVDD and finally REFIN.Note that in this mode, the minimum required head room and foot room for the output amplifiers must be met."

Can the loop power source be tied to AVDD VPOS_IN and PVDD? DVDD will be fed via LDO also from the external loop power source. Of course the power-on should be sequenced then. Isolation of the SPI will be taken care of.

"

Thank you in advance.

Regards,
Maynard

  • 0
    TI__Guru* 93715 points

    Maynard,

    It shouldn't be a problem for the device to run off of the loop power. In that case, you would use some LDO to drive VPOS_IN, AVDD, and PVDD from the same voltage. It's important that all of them are tied together to the same point. It would be connected just as shown in Figure 131, as below:

    If you are thinking about something like this, I would recommend getting a DAC8771EVM and testing this circuit.

    Joseph Wu