AD5544 - Temperature Drift of Resistors

Hi,

I'd like to generate a DAC output voltage that is greater than the reference voltage I provide to the DAC. Referencing figure 22 of the datasheet, I believe I can do so by adding an external resistor in series with Rfbx that increases the gain of the transimpedance amplifier. The problem I can see with this is that the full-scale range of the DAC will drift as Rfbx varies in resistance due to fab variations or temperature. I see in the datasheet that the resistance of Rfbx will vary from 4k to 8k depending on the device. But how does it vary over temperature?

Thanks,

Peter

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  • Hi Peter,

    The shift from 6k typical value @ 25C to 4-8kOhms is primarily due to change in temperature.

    What I suggest is include an additional amplifier with a gain=2 after the transimpedance amplifier so the gain will not be highly dependent on the TC of the integrated resistors.

    Cheers,

    Ivan

Reply
  • Hi Peter,

    The shift from 6k typical value @ 25C to 4-8kOhms is primarily due to change in temperature.

    What I suggest is include an additional amplifier with a gain=2 after the transimpedance amplifier so the gain will not be highly dependent on the TC of the integrated resistors.

    Cheers,

    Ivan

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