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LDC1000: cfb pin signal

Andre Lukassen
Prodigy 220 points
Part Number: LDC1000


Hi guys,

the LDC has got an active filter. If the capacitor to low between CFA and CFB, then the filter goes saturate. 

Is the filter in saturation or not at the measured signal?

regards

André

  • 0
    TI__Genius 17440 points

    Hi Andre,

    In the picture you provided, your signal is clipping when it reaches 0V. It looks like it's about 2V peak-to-peak. It's critical to keep the peak-to-peak voltage across the filter capacitor at 1V, otherwise the LDC1000 will not function correctly. I would recommend using larger capacitors until you see 1Vpp on the CFB pin. Section 8.2.1.2.3 of the LDC1000 datasheet shows an example of a correct CFB waveform.

    Note that you need to have correctly set your Rp_min and Rp_max values before choosing a filter capacitor, as changing either of these values could force you to change the filter capacitor.