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OPA333: chopper frequency of opa333 and charge pump frequency of opa2325

Rui Zhang35
Prodigy 210 points
Part Number: OPA333
Other Parts Discussed in Thread: OPA2325, , OPA325

Hi there,

I am running some tests of opa333 and opa2325 it would be nice if some one can tell me the chopper frequency of opa333 and the internal charge pump frequency of opa2325

thanks in advance

  • 0
    TI__Guru 60610 points

    Rui,

    The chopping frequency of OPA333 is around 125kHz (every 8us) while the charge pump frequency of OPA325 is about 11MHz (above the unity-gain bandwidth).

  • 0 in reply to Marek Lis
    Prodigy 210 points

    Hi Marek,

    Thank you for your answers. If it doesn't bother I do have a further question for spectrum of OPA2325.

    I see a harmonic around 500kHz and had some modulation with input signal which I couldn't explain it, picture is attached.

    Signal Input is by 30kHz with 1V amplitude, 1V offset. This harmonic appears during all my tests and modulated with almost every input signal.

  • 0 in reply to Rui Zhang35
    TI__Guru 60610 points

    Rui,

    500kHz harmonic in OPA333 could easily be explained (4*125kHz) but seeing it in OPA325 is not obvious.  The only thing I can think of is that it could be related to the switching frequency of power supply you use or it's 16th harmonic of your input signal (16*30kHz=480kHz).