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DAC8775: DAC8775 POC bit for voltage mode

Eddie Chou
Expert 4710 points
Part Number: DAC8775

Hi Team,

In DAC8775 datasheet, while Voltage and Current Outputs shared terminal, 

When the voltage output is active and the current output is inactive the IOUT_x pin becomes a high-impedance node and therefore does not significantly load the voltage output in a way that would degrade VOUT_x performance

May I know what performance degrade with voltage mode if POC = "0", will it damage device if voltage mode with high impedance?

Thanks for support.

Eddie

  • 0
    TI__Guru* 92715 points

    Eddie,


    I'm sorry I missed this post.

    With POC set to 0, there is a 30kΩ resistor from VOUT to PBKG that is enabled any time the VOUT is disabled (this is included in the condition for power-up, and hardware and software resets). With POC set to 1, the output for IOUT and VOUT are set to HiZ outputs under the same conditions. When operating VOUT there should be no effect on the VOUT operation. In either condition, it should not damage the device.

    I would note that often, IOUT and VOUT are connected together (as it is in the EVM through some 15Ω resistors). If POC is set to 0, the 30kΩ resistor is enabled when VOUT is disabled. When IOUT is enabled during this condition, you should set POC to 1 to remove the 30kΩ resistor. The 30kΩ resistor is set in parallel to the load resistor and may appear as a gain error with the load resistance.


    Joseph Wu