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DAC8871: DAC8871 Buffered Reference Connection

Ted H
Intellectual 275 points
Other Parts Discussed in Thread: DAC8871, OPA2277

Figure 40 in the datasheet shows buffer driven reference inputs with an RC low-pass on both VREFH-F and VREFL-F.  Can you please provide guidance regarding appropriate values for these components as well as the feedback capacitor on each OPA2277 op-amp?  I am constrained on the size of the resistor, as I want to minimize the divider drop into the 7.5kohm input resistance.  It is interesting to note that the evaluation board for the DAC8871 does not implement this topology for the reference inputs.

  • 0
    TI__Genius 14220 points
    Hi Ted,

    Thank you for your query. You can look at the following E2E thread for the clarification. You are right that the EVM provides a simplifies circuit. The feedback components on the reference buffers are used for better stability of the system, which is a factor of the opamp used and the input impedance of the reference inputs of the DAC.

    e2e.ti.com/.../2303065

    Regards,
    Uttam Sahu
    Applications Engineer, Precision DACs