Dec 18, 2013 · Power that must be delivered by a USB port is defined in Section 7.2.1 of USB 2.0 Specifications. To start, the power delivery is defined in "units of load". For USB 2.0 one unit is 100 mA, and for USB 3.x one unit is 150 mA. USB standard defines two classes of USB ports, "high-power ports", and "low-power ports" The specs says, page 171:

Sep 11, 2016 · Per the base specification, any device attached to an SDP must initially be a low-power device, with high-power mode contingent on later USB configuration by the host. Charging ports, however, can immediately supply up to at least 1.5 A.

Jul 16, 2019 · For USB-C the minimum to meet the USB 3.0 spec is 1.5 amps. The maximum for USB-C is 3 amps, unless using USB-PD at 20 volts or more then it's 5 amps. Power out of a hub cannot exceed what goes in. The USB spec says a port must be able to provide 900 mA minimum, but there are exceptions for hubs. On a hub it may only be required to supply 150 mA.

The USB-IF has bumped up the maximum allowed current on USB-A over time and last I checked it allows a maximum of 2.4 amps. The voltage allowed on USB-A is 5 volts, at least according to USB-IF. There was the USB-PD 1.0 spec that allowed higher voltages on USB-A but I have not seen anyone actually use that spec in any devices available to the ...

Feb 8, 2017 · You probably don't want to increase the voltage, although USB charged devices seem to be incredibly robust. The new USB Power Delivery spec will probably only be ever seen in USB 3.1 and requires compatible devices on both ends plus a special cable but can supply up to 20V @ 5A for 100W charging of laptops.

Apr 20, 2022 · In reality, most USB ports can output more current than the standard defines but a standard-compliant device will not draw more power than the standard allows. According to the USB standard the following limits apply: USB-A port 2.0: 0.5A; USB-A port 3.0 (now called USB 3.1/3.2 Gen 1): 0.9A

Jun 7, 2023 · with the first two listed options being USB 2.0 power (5V 500mA) and USB 3.2 power (5V 900mA). It lists "USB Type-C Current @ 1.5 A" as an option that the USB-C port can provide, but my reading of it doesn't imply that a port that doesn't output 1.5A isn't compliant. –

Nov 28, 2021 · D - USB output - connect load here. E - voltage down - press to reduce power delivery test voltage. F - voltage up - press to increase power delivery test voltage. Simply connect to the USB C power supply or battery pack, then use the two buttons on the monitor to select the trigger voltage - 5, 9, 12, 15 or 20V DC.

Feb 4, 2022 · Devices that want more power can use USB 2.0, USB-BC, USB-PD, or some other protocol to ask for more power. If there is not enough power available then the request is denied and, presumably, the device will respect that denial. This is safe because the USB host will know to keep a reserve in the bookkeeping for new devices to make these requests.

Jul 15, 2020 · The Creative Pebble V2 speaker specifies a requirement of 5V/2A. I am trying to make sure the USB 3.1 Gen 2 port can deliver the speaker enough power. If the port can provide 15-20W, it should be enough. The wiki says the USB 3.1 Gen 1 port has a maximum of 5V/0.9A only. I have to resort to the Gen 2 port.