O que é esse estranho cabo USB
O cabo é chamado de cabo Y USB . Ele é projetado para dispositivos que exigem mais potência do que a disponível em uma única porta USB.
Quais são os dois tipos diferentes de cabos Y?
One male connector, two female connectors
There are two types of the one male two female cables. One is a basic charging cable, splitting one port's power across two devices. The other is a specialised cable that somehow splits the data lines - and it's only used in very specific applications.
Two male connectors, one male or one female connector
What happens is you have your USB cable, one side for the host and one for the device, but with an extra connector attached. This extra connector does not have any data lines (D-, D+); it only has the power lines (GND, VBUS). It's attached in parallel to the existing cable. In other words, VBUS is connected to VBUS and GND is connected to GND.
Fonte Posso conectar com segurança a extremidade somente de energia de um cabo USB-Y a outra fonte de alimentação? responder por Bob )
Então, o que é esse estranho Y-Cable?
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Requisitosdeenergia
Somedevices,suchashigh-speedexternaldiskdrives,requiremorethan500mAofcurrent[89]andthereforemayhavepowerissuesifpoweredfromjustoneUSB2.0port:erraticfunction,failuretofunction,oroverloading/damagingtheport.
SuchdevicesmaycomewithanexternalpowersourceoraY-shapedcablethathastwoUSBconnectors(oneforpoweranddata,theotherforpoweronly)toplugintoacomputer.Withsuchacable,adevicecandrawpowerfromtwoUSBportssimultaneously.However,USBcompliancespecificationstatesthat"use of a 'Y' cable (a cable with two A-plugs) is prohibited on any USB peripheral", meaning that "if a USB peripheral requires more power than allowed by the USB specification to which it is designed, then it must be self-powered."
Fonte USB