ADD5211 Cout,inductor scream issue

Good day,

         We use ADD5211  for four-string LED driving, input voltage is 12v, output voltage is 20.4v/89mA per string.

All parameters follow the datasheet and tool guidance, ADD5211 can delight the LEDs but scream issue happen with Cin, Cout and boost Inductor. We try to increase the Cout value and adjust the comp circuit, still can not solve this issue. Can you kindly help to advice or share the debug experience about this chip, thank you.

Below is the schematic.



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[edited by: Verti at 8:41 AM (GMT 0) on 21 Feb 2019]
  • 0
    •  Analog Employees 
    on Mar 7, 2019 5:10 AM

    the MLCC capacitor has the piezoelectric effect, which may cause the noise (scream) on the capacitor, could you replace the capacitor with other vendors capacitor or another type of capacitor to check if the issue gone?

    for the inductor, the vibration of the wind also will cause the scream. if the noise is coming from the inductor, please change another inductor and see if issue goes ( you can use flat winding inductors )