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DAC7811EVM: Increase slew rate of DAC7811

user4858620
Prodigy 200 points
Part Number: DAC7811EVM
Other Parts Discussed in Thread: DAC7811, BUF634A, OPA2277, THS3062

Hi.

I am using DAC7811EVM board.

I would like to increase the slew rate of DAC7811 output.

OPA 2277 on the evaluation board has a low slew rate.

So, I chose BUF634a with a high slew rate.

Which of the following two is the correct circuit configuration when combined with the evaluation board?
(Or are both configurations wrong?)
①.Swap OPA 2277 and BUF634a as shown below.
②.Add BUF634a after OPA2277 as shown below.
I thought that ② was limited by the SR of OPA2277, so the rise / fall time would not change even if BUF634a was added.
Therefore, I connected the DAC7811 evaluation board and the BUF634a evaluation board with jumper wires as shown in ① configuration.
But, no voltage was output.
Best Regard
  • 0
    TI__Genius 14220 points

    Hello,

    Welcome to E2E and thank you for your query. I couldn't see the attachments. Could you please upload them again. Note that the slew rate will be limited by the slowest component on the path. Hence, you need to remove OPA2277 and use a high slew rate amplifier such as THS3062 or an equivalent part. The slew rate of OPA2277 is very small and that will limit the overall slew rate of the circuit.

    Hope that answers your question.

    Regards,

    Uttam Sahu

    Applications Engineer, Precision DAC