DAC8871: figure 39 operation with OPA211

Ryuji

Guru 20090 points

Part Number: DAC8871
Other Parts Discussed in Thread: OPA211, TINA-TI

Hello,

Does the figure39 of the DAC8871 datasheet schematics with OPA211 operate correctly?
I simulated the OPA211 operation on the TINA-TI. Please see the attached file as simulation result.
I think that we should add a capacitor in parallel with 6.2kohm.

Buffer.pptx

Best Regards,
Ryuji

over 7 years ago

0 Uttam Sahu over 7 years ago

TI__Genius 14220 points

Hi Ryuji,

Thank you for your query. You are right - the application circuit of Fig 39 hasn't considered the stability issues, probably due to simplicity. The bias current cancellation resistors do induce instability in the circuit and a capacitor in parallel to the 6.2k will surely help. Please find below a nice explanation of the circuit at the following link:

e2e.ti.com/.../resistors-in-the-feedback-of-a-buffer-ask-why

Regards,
Uttam Sahu
Applications Engineer, Precision DACs

Data converters

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DAC8871: figure 39 operation with OPA211