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OPA2277 HF oscillation

Alexander Kazakevich
Prodigy 150 points
Other Parts Discussed in Thread: OPA2277, TLC2652

Colleagues

our customer Mekhanotronika reports of problem with OPA2277 amp.

 As they say, there are high frequency (>100MHz) oscillations of small magnitude (<1mV). If they load 100pF cap, the oscillations disappear. It is critical for them as they use 16ch amps then MUX and ADC. The oscillation from one channel deliver changing signal in another channel.

Now they test the system and they are not sure to use OPA2277 in serial production.

Is there any information concerning such OPA2277 behaviour? They can use some AD867x instead our OPA.

 BR

Alexander Kazakevich

  • 0
    TI__Guru* 93105 points

    Hello Alexander,

    I am going to investigate this question and will answer you off of the open forum.

    Regards, Thomas

  • 0 in reply to Thomas Kuehl
    Prodigy 10 points

    Can OPA277PA or TLC2652 use single positive power supply only?

    Regards

    Junhua

  • 0 in reply to Junhua Wang
    TI__Guru* 93105 points

    Junhua,

    The OPA277PA and TLC2652 are optimally designed for dual-supply operation. But when it comes to single-supply operation the TLC2652 looks like it may be more easily applied. Its common-mode input range extends to the negative supply rail which is usually 0V in a single-supply application. The output voltage swing range is within a few tenths of a volt of the supply rails for both the positive and negative swing. The TLC2652 is a chopper-stabilized operational-amplifier and does require the addition of some external capacitors as shown in the data-sheet. These normally connect to the Vdd- which would be 0V in the single-supply use. Just make sure that all of the dual-supply parameters are scaled to the single-supply application and I think it will be okay.

    Although the OPA277PA could be used in a psuedo single-supply application the common-mode input voltage and output swing limits would have to be observed and dealt with in the application.

    Thomas

    PA - Linear Applications Engineering