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I'm designing a single channel 4-20 mA current loop transmitter using XTR111 IC. By following the reference design guide from TI.

link: https://www.ti.com/lit/pdf/tidub12

Circuit schematic reference: https://www.ti.com/lit/pdf/tidrwl8

In the schematic, why the REF5050AIDGKT voltage reference IC is used? What is the purpose of it?

Power source: 24 V local power supply

Can't I give a 3.3 V supply from my external LDO to DAC VDD that is derived from the same 24 V supply and voltage to DAC Vref pin from the Vreg pin of XTR111?

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Can't I give a 3.3v supply from my external LDO to DAC VDD that is derived from the same 24v supply and voltage to DAC Vref pin from the Vreg pin of XTR111?

Yes you can but, how much accuracy deviation are you prepared to tolerate in your design; a voltage regulator that provides a voltage reference to a DAC is normally the most desirable approach when it comes to accuracy and drift minimization.

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  • \$\begingroup\$ So I can connect both Vdd and Vref to LDO output(3.3v). But the datasheet says Vreg pin of XTR111 should be connected to DAC Vdd. \$\endgroup\$
    – John Mist
    Commented Jun 8, 2023 at 9:42
  • \$\begingroup\$ Please use part number references in the schematic you linked to avoid ambiguity. Please also link the data sheet and page number that says what you said. \$\endgroup\$
    – Andy aka
    Commented Jun 8, 2023 at 11:19
  • \$\begingroup\$ Part no. (Voltage Reference—REF5050A) IC from page no. 6 from the first link is unavailable locally, so what should be the alternate method to proceed? \$\endgroup\$
    – John Mist
    Commented Jun 8, 2023 at 13:30
  • \$\begingroup\$ I thought that question was answered in my answer above. \$\endgroup\$
    – Andy aka
    Commented Jun 8, 2023 at 14:13

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