Inductance scream,

The basic idea is that harmonics in the auditory range are heard.
However, as long as the switching frequency of general switching power supply is not within the 20K range, its harmonic content will not cause great noise.
But this theory is based on the switching power supply switching frequency is relatively stable.
Therefore, if the duty ratio of the switching power supply is unstable, the harmonic generated by it is likely to be within 20K and the amplitude is large, thus causing the auditory effect.

The solution to the inductive roar

  1. Reduce the load current or replace the DC-DC with slightly larger power.
  2. Fundamentally solve the instability of duty cycle. Generally, the small signal of control loop is interfered by noise, and the duty cycle of DC/DC needs to be adjusted to be very stable.

3, replace the inductance, adjust the capacitance, will also improve, but absolute elimination is not easy.

  1. Soak the glue (the best hard sealing material of epoxy resin), then put it into the empty chamber to vacuum and extrude the bubbles inside.
    No deformation and vibration after curing.

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