Prime Power Switching Adapter

[matthiaspaul]

(09-20-2015 03:52 AM)Skyblues Wrote:  Output = +5V 1A

While Hewlett-Packard was (among Apple, Sony, Samsung and a few others) one of the companies who have implemented their own proprietary and incompatible USB charging schemes in the past, the HP Prime was introduced in 2013, therefore I strongly assume that it follows the USB Battery Charging Specification (BCS) 1.2 (scanning the manual revealed nothing, though).

So, any USB power adapter compliant with the USB BCS 1.2 and capable to deliver 1.5A at 5V should work, regardless of manufacturer. While based on the label of your adapter the Prime does not seem to draw more than 1A while charging, I recommend to go for a DCP (Dedicated charging port) adapter providing not only 1A but up to 1.5A, so that the adapter can be used universally for any devices following the BCS. After all, the whole idea of the USB Power Delivery Specification (PDS) and the USB BCS is to finally have a universal power delivery, charging and power connector standard for an extremely wide range of consumer electronics devices regardless of manufacturer in order to avoid unnecessary environmental pollution by reducing waste.

While there should be an abundance of suitable DCP adapters available, it is also very easy to build your own: All you need is a power adapter delivering up to 1.5A at 5V and a suitable USB connector. Connect the +5V wire to VBUS (pin 1) of the connector and 0V to GND (pin 4). Then short the D+ (pin 2) and D- (pin 3) pins in the USB connector. A device supporting the BCS will find out that it is connected to a BCS compliant DCP by detecting the short between the otherwise floating (no pullups or pulldowns in the adapter!) D+ and D- lines. If the device is not BCS compliant, the short of the data lines will not cause any harm, but the device may charge very slowly (with 0.1A only) or not at all. (There are also dumb devices out there, which don't care about negotiation at all and just draw the power they need - however, such devices are not only not compliant with the optional BCS, but they actively violate the USB specification and would not be allowed to carry the USB logo. Therefore I don't assume that the Prime is one of them. Either way, in this particular case it would work anyway, for as long as the source provides enough current (at least 1A per your label).)

Greetings,

Matthias