3 ms·
Nitpick: It's current negotiation, not voltage negotiation. As for voltage - 5V is universal with USB. And as for current - I wrote about the matter in another
by hwh 13y ago
Nitpick: It's current negotiation, not voltage negotiation. As for voltage - 5V is universal with USB.
And as for current - I wrote about the matter in another reply to the OP: The problem will be a well-behaved USB device simply won't take more than 100mA. I.e. it will use the "flat" charging curve, even if the host could deliver more.
- SEMW 13y ago> As for voltage - 5V is universal with USB Nitpick for interest's sake: apparently there's a new (2012) 'USB Power Delivery' spec[1] which specifies two new voltage levels (12V & 20V) in addition to 5V, with higher current limits (2A at 5V, 3A at 12V or 20V for microUSB connectors). Obviously both ends (and the cable) have to support it; I don't know if anything actually does yet. [1] http://www.usb.org/developers/powerdelivery/ http://www.usb.org/developers/powerdelivery/
- Piskvorrr 13y agoPedantry: That should be obvious from the units, wouldn't it? (Volts for voltage, amperes for current, ohms for resistance) I do agree that the general public uses these interchangeably, bringing confusion :) As for a well-behaved device - there aren't very many of those, either. Fortunately, this is less of a problem with USB3 - more devices follow the spec closely.