why TPS54620 make noise ?

Hi Team,

My design as below:

Input = D5V_IN = 5V

Output= 4.8 V

Once power on , I can hear the noise from the chip around , the noise is piercing and it continue till power off.

I decline the output voltage , when output below 4.7V , the noise is weaker , when below 4.6V I can not hear the noise.

May I ask how the noise produce and how to reduce the damn noise.

Thank you.

daw y：

测量PH1及PH2波形看看。

daw y：

估计是输入电压太低了，输入电压太低，占空比几乎达到最大，BOOST电容无法充电，因此电路工作在震荡状态造成的，你可以试试输出4.8V，但输入调整到5.5V，应该也是没有噪声的。

Johnsin Tao：

回复 daw y:

Hi估计都100%duty了输入走线宽一点，输入电容22uF尽量靠近芯片输入脚，选择尽量小电感DCR的电感。同时将电感饱和电流选大一点。