<story><title>USB Condoms</title><url>http://usbcondoms.com/</url></story><parent_chain><item><author>peterwwillis</author><text>Two things:&lt;p&gt;1. The data lines can be very important in regulating power output for different devices, and there are different maximums for different versions of USB. Some devices require data communication to charge. Some require proprietary protocols. Implementing Apple product charging is somewhat convoluted, for example, and has changed over time.&lt;p&gt;2. A friend of mine is a computer engineer, and tells me that correctly implementing USB in hardware is incredibly difficult. It&amp;#x27;s possible that devices like these might be skimping on parts of the spec to more easily get a working product out the door.</text></item></parent_chain><comment><author>megaframe</author><text>I used to design these things. Yes they are difficult to design in the sense of RF engineering to pump that much data on a data line, but the power end of it is a very simplest design. It has a current cap to prevent damage to the regulator circuit and USB regular spec is 0.5A. Which isn&amp;#x27;t very much if you&amp;#x27;ve ever tried to charge a phone off of that. Without the inner pins it&amp;#x27;ll default to the low spec (on a well design USB Host) but no damage or risk to having those inner pins float since they have internal pull up resistors. If the device decides to provide more all the better for you as your device is what regulates how much current it wants when an infinite amount is available.</text></comment>
<story><title>USB Condoms</title><url>http://usbcondoms.com/</url></story><parent_chain><item><author>peterwwillis</author><text>Two things:&lt;p&gt;1. The data lines can be very important in regulating power output for different devices, and there are different maximums for different versions of USB. Some devices require data communication to charge. Some require proprietary protocols. Implementing Apple product charging is somewhat convoluted, for example, and has changed over time.&lt;p&gt;2. A friend of mine is a computer engineer, and tells me that correctly implementing USB in hardware is incredibly difficult. It&amp;#x27;s possible that devices like these might be skimping on parts of the spec to more easily get a working product out the door.</text></item></parent_chain><comment><author>charliesome</author><text>&amp;gt; &lt;i&gt;Implementing Apple product charging is somewhat convoluted, for example, and has changed over time.&lt;/i&gt;&lt;p&gt;It is? I&amp;#x27;ve never had any problems with cheap AC to USB power adapters.</text></comment>