Forums › General Discussions › USB port current
- This topic has 4 replies, 4 voices, and was last updated 3 years, 9 months ago by
Jim_Pennell.
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mclineParticipantIf I understand the USB3.0 specification for power, each port should be able to deliver at least 900mA. I measured the current draw of the VSG60 and the BB60C, and each is about 1300mA. That is 400mA over what the USB 3.0 port may be capable of. Have you seen any issues where a port is damaged or stops working due to current draw being greater than 900mA? Do you have any recommendations for a USB HUB?
Thanks
AndrewModerator- This reply was modified 3 years, 1 month ago by
Andrew.
mcline,
In general we have found that most USB 3.0 ports will provide enough current to run the BB60C and VSG60 off of a single USB 3.0 connection. Where the second cable/connection is usually needed is on ultraportable laptops, ones that are optimized for low power consumption like the MS Surface Pro. I have not seen a port become damaged, but on those low power laptops, sometimes what you will see is Windows will shut off that port if it detects high current draw. It’s restored on a PC restart. If you have a machine that exhibits that, usually a powered hub is the best workaround.
When both connections of the y-cable are used, we don’t generally see any issues.
I would recommend the following 3 USB hubs, we know they work with our receivers and have been used to connect multiple devices simultaneously.
https://www.amazon.com/dp/B014ZQ07NE/ref=emc_b_5_i
Let me know if you have follow up questions.
Jim_PennellParticipant- This reply was modified 3 years, 9 months ago by
Jim_Pennell. Reason: minor spelling error
I noticed, in the prior post, that a user measured the BB60C as pulling approximately 1.3 Amps.
By adding a USB3 at 900 mA and a USB2 500 mA, total current that is available is a rated 1.4 Amps.
USB3 ports may, and often do, supply more then the rated 900 mA but this is ‘iffy’ depending on the particular hardware like the USB3 Hubs that Andrew mentioned.
I have a application where I intend to use a relay to switch power to the BB60C on and off. I will also be switching power to a different USB device. Turns out, the BB60C driver and the one for the other device terminally confuse each other if both devices are plugged into the same PC.
I am using a switchable USB3 hub, but hacking in to install my relays to allow a PC to turn each one on and off so that only ONE of them is running at any given time.
However, I would like to confirm if the BB60C does pull 1.3 Amps.
Fortunately, the USB3 Hub I plan to use has a good external 5 VDC supply and can easily source the current I might need.
I checked the Data sheets, and the BB60C only specifies needing one USB3 and one USB2 but does not indicate a real number for the BB60C.
Andrew, do you have any information to confirm the BB60C current demand ?
Regards, Jim Pennell
Justin CrooksModeratorJim,
We typically see 1.2 amps, but depending on mode and input voltage, 1.3 amps would be at the high end of the normal range. About 1/2 of the power draw is from switching regulators, the other half from LDOs, so current can be a little higher if the voltage is lower.
Jim_PennellParticipantThank you, Justin.
I can understand a bit of variance on the input current with Switching power supplies. I am pleased with having a approximate current number. It helps my current thinking and the rating I need for a USB3 Hub.
It also makes certain that using a PC USB3 port will most likely NOT have enough current, so the second connector on the cable has to be plugged in as well to make up the difference, otherwise one should expect flaky performance….
Regards, Jim
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