It isn't the voltage available, but the current that a USB jack is capable of. A standard USB 2.0 port supplies a maximum of 500 mA (0.5 A). I could only find one reference to the power a Stick consumes, and that was 3 watts. 3 watts at 5 Volts DC is 0.6 A, so a TV USB port is at its limits powering a Stick. Your only option, besides connecting your devices to their own separate power source, would be to use a powered USB hub. That way neither unit is drawing power from the TV.
Last edited by atc98092
on Wed Dec 05, 2018 12:44 pm, edited 1 time in total.
Nvidia Shield, Roku Stick (3600), Ultra (4640), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.