Why does my console turn on by itself?

I have searched through the internet but couldn't find someone else who asked this question

I have a ps3 super slim. When I turn it off (standby mode) while the controller is connected to the usb port, the console will automatically power on again. Disconnect the controller and I can turn the console off alright. Reconnect the controller while the console is turned off, and it will automatically power on again!

Is there a setting option for this issue? Is it how ps3 works or is it a problem?