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OPA549: OPA549 Reference Design

Part Number: OPA549

Hi All,

What is the true connection for Ref pin in symmetrical supply (V+, V-) design. Ref pin is connected to GND as shown in Figure.1

And according to below explanations, Ref pin must be set at V-   Which Ref pin connection method is true for symmetrical opamp supply?

Figure.1 and explanation for Ref pin can be found in below link (pg.8):

www.ti.com/.../opa549.pdf

Thanks in advance

  • According to the explanation you quoted, Ref must be set at V− only if the minimum VS is used. In Figure 1, V+ is larger than 8 V, so connecting Ref to the ground is allowed.

  • Clemens Ladisch, thanks for your answer. In this case, which one is better for opamp performance?
  • As far as I can see, the value of the Ref pin does not really affect the performance of the output.

    This pin exists to give you more flexibility; you can choose to connect it to whatever potential that makes controlling ILIM or E/S easier.

  • Hello muratE,

    Clemens' explanation is exactly spot on. Where you set the REF level comes down to what is convenient for the circuit, and within the range specified in the CONTROL REFERENCE (REF) PIN section, on OPA549 datasheet Pg. 8. Where you set it within that range will have no effect on the overall performance of the OPA549 operating as a linear amplifier. Its function is completely related to the current limit (ILIM) feature of the amplifier. FIGURE 2 on datasheet Pg. 9, Adjustable Current Limit, provides a little more insight into the ILM circuit and the REF pin 6 role in the circuit.

    If you are using dual supplies for the OPA549, GND is usually a convenient level to connect REF to.

    Regards, Thomas

    Precision Amplifiers Applications Engineering

  • muratE

    We haven't heard back from you so we assume this answered your question. If you need additional assistance, post another reply below.

    Thanks
    Dennis
  • Thomas,

    Thanks for your answer.

    I use dual supply to sinusoidal output. I used GND as a REF point as you recommended.

    Dennis,

    Thanks for your interest.


    Regards.