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TAS2552: Switching Noise on Input Power Supply

Chi-wen Wang
Intellectual 920 points
Part Number: TAS2552

Hi,

  We got our first TAS2552 based design back but we have been struggling with noises related issues.

  Attached i she schematic of our TAS2552 based design and the input power supplier is 3.3V with up to 2A current.  TR71 & TR72 are just symbols that represent traces connecting different ground planes.

  Even without any audio input, we observed ~800mV peak-to-peak switching noise on the input power supply (=ASSRY_PWR).  A screen shot from scope is attached too.  We tried to increase the input bypass capacitor but that didn't seem to have.  Does anyone have any suggestion?

  • 0
    TI__Guru** 109875 points
    Hi Chi-wen,

    The inductor and capacitors connected to the boost pins of the TAS2552 are similar or the same as the recommended in the data sheet?
    The recommended values are in table 12, page 42-43.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators
  • 0 in reply to Ivan Salazar
    Intellectual 920 points
    Hi Ivan,
    We use TDK VLS6045EX-2R2N 2.2uH inductor with DRC = 19m ohms and IDC max = 7.5A. We use 10uF for boost convert input capacitor and 10uF for output capacitor (this is lower than what the data sheet recommended.) Even if we changed output capacitor from 10uF to 22uF, things didn't improve.