OPA549: OPA549 Reference Design

murat erdogan

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

over 5 years ago

0 Clemens Ladisch over 5 years ago

Guru 244390 points

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

0 murat erdogan over 5 years ago in reply to Clemens Ladisch

Prodigy 30 points

Clemens Ladisch, thanks for your answer. In this case, which one is better for opamp performance?

0 Clemens Ladisch over 5 years ago in reply to murat erdogan

Guru 244390 points

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 I_LIM or E/S easier.

0 Thomas Kuehl over 5 years ago in reply to Clemens Ladisch

TI__Guru* 93105 points

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

0 Dennis Goeke over 5 years ago in reply to Thomas Kuehl

TI__Genius 11135 points

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

0 murat erdogan over 5 years ago in reply to Thomas Kuehl

Prodigy 30 points

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.

Amplifiers

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OPA549: OPA549 Reference Design