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Dac8760 running with single supply 0V & 12V

Tom Allen1
Prodigy 70 points
Other Parts Discussed in Thread: DAC8760, LM7705

Hi,

I am running a DAC8760 on 0 and 12V rails. On the 0-10V output there is an offset of approx 10.5mV at Zero.

  • I guess that running on dual rails is the only way of obtaining a true 0V output?
  • Is there any issue with using asymmetric rails e.g 12V and -5V.
  • Can you recommend an inverter to generate the negative rail from either 12V or 5V
  • 0
    TI__Mastermind 46290 points

    Tom,

    Yes - when using the device in a single supply configuration the output amplifier will suffer from output voltage swing to rail limitations near zero-scale. While there isn't an official specification for zero-scale error with a single-supply configuration, your observations very closely match what my colleagues and I have measured and the data we reported in SBAA199 (see Figure 12).

    A dual supply configuration will help you realize stronger performance near zero-scale for the unipolar output ranges. There is no issue with using asymmetric supply rails, in fact the datasheet specification for zero-scale error in the unipolar output ranges provides a -500mV supply rail to give some "footroom" to the output buffer.

    I have used/recommended the LM7705 as a solution to this issue in the past with good success. The LM7705 provides a negative bias of ~232mV, which is a little bit short of the -500mV bias in the DAC8760 datasheet, but it has effectively achieved datasheet performance in all the units that I have measured.