# TechReport: Research about USB as Power supplied ## USB has poor PSRR PSU when you didn't handle it * Refer to [here](https://andybrown.me.uk/2015/07/24/usb-filtering/), this website describe phenomenon and LC-filter solution * Vpp of noise about 100mV ## Can't delivery both data and power in the USB-PD mode Refer to [here](https://superuser.com/questions/1555007/does-usb-c-power-delivery-also-support-data-transfer) ###### tags: `TechReport` `DeWei`