Our customer is using the TPS56339DDCR DC/DC Buck converter. They are having issue with audible noise coming from the input capacitor. According to the customer,
We are having an issue where the input capacitors are creating an annoying buzzing/whining sound which I believe is due to the piezoelectric effect, since we are using ceramics. The switching frequency of the TPS56339 is 500 KHz, which is not within the audible frequency range. However, we are using an LED control card that connects to the PCB we have designed that has an operating frequency/clock rate of 500 Hz.
My question is can you suggest anything to mitigate the sound from the capacitors?
Could I use aluminium electrolytic capacitors instead of ceramics for example?
I have attached an image of the circuit from WeBench power designer.
The capacitors are actually creating the buzzing sound under a heavier load, for example when over 1.5A are being drawn the buzzing is very noticeable.
My theory is that it is something to do with the LED control card that we use that has a refresh rate of 500 Hz. The buck converter is powering devices that read an SPI signal from this controller. Honestly I don't know why that would cause the capacitors to vibrate, but I have powered the buck converter up to a similar load without the 500 Hz control card and there is no audible noise.
Really we need to know if it is okay to use an alternative capacitor material? Tantalum is probably the next best we could use due to the relatively simple footprint size.
Thank you for your support!