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OPA541 voltage follower configuration

James Zhu
Prodigy 125 points
Other Parts Discussed in Thread: OPA541, DAC8734

Hello, 

I'm trying to use OPA541 as a voltage follower. However, I couldn't see the pure sine waveform from the output. The 1.74V sine waveform input for the amplifier is from TI DAC8734 analog output channel. 

My OPA541 connection is as follow:

The output I got was (with phase and frequency distortions):

 

Could anyone please shed some light on this issue? Thanks in advance!

Regards,

James

  • 0
    TI__Genius 15410 points

    Hello James,

    Is there anything connected to the output of the OPA541 such as a capacitor or inductor? Having a capacitance or inductance (such as a motor winding) can cause stability issues with amplifiers.

    Also, can you please provide oscilloscope shots of both the input and output of the OPA541?

    -Tim Claycomb

  • 0 in reply to Tim Claycomb
    Prodigy 125 points

    Hi Tim, thank you very much for your reply! There's only one oscilloscope connection to the OPA541 output. Other than that, nothing else connected. 

    My 11-pin OPA541 PIN connections are:

    PIN 1: signal input from DAC8734 analog output

    PIN 3&4 are jumpered to connect -Vs

    Pin 5 &7 are jumpered to connect PIN 2, wired to monitor point  

    PIN 10 & 11 are jumpered to connect +Vs

    Please see the screen shots for the input signal (Channel 2) along with the outputs (Channel 1): 

    Thanks,

    James

     

  • 0 in reply to James Zhu
    TI__Genius 15410 points

    Hi James,

    Is the tab of the OPA541 connected to -Vs?

    I noticed that the third oscilloscope shot appears to be working as expected. Can you please share what the difference is between the four oscilloscope shots? Please provide frequency and amplitude.

  • 0 in reply to Tim Claycomb
    Prodigy 125 points

    Thanks Tim! Just figured out: I should've connected the power supply source COMMON to the oscilloscope ground.. Before, the four shots were from the same case tested, the output was oscillating. Everything appears to be normal now. The frequency is around 60Hz and amplitude is around 2.5V.