This device is fabulous with its convenient micro USB charging port with OTG support. No bulky wall wart to lug around. But it refuses to charge normally from any charger+cable except for the (too short) one that came with it.

My plethora of USB chargers, adapters, powered hubs and more will only trickle charge the T100 and take tens of hours. And it’s not just the device’s 2.0A current requirement, either. There’s something more going on.

Just Say “Charge it!”

The USB Innovators Forum (USB-IF) has a whole power delivery strategy with goals as shown below. Simply stated, USB is now flexible enough to provide the right amount of power to either end of the USB cable.

The reason for UBC is that newer devices like Apple’s iPad, Samsung’s Galaxy S5 and Galaxy Tab devices–and quite possibly my Asus T100 2:1–consume more current and sometimes have the ability to source power to the host device. UBC flexibly delivers the right amount of power and can avoid charger waste.

Communications protocols between the battery’s MCU and the charger’s MCU know how to properly charge a 3000mAh to 10, 000mAh battery. Battery chemistry matters, too. As does watching out for heat and thermal runaway; some USB charger ICs take these factors into account.

Apple, ever the trend-setter (and master of bespoke specifications) created their own proprietary fast charging profiles called Apple 1A, 2A and now 2.4A. The Chinese telecom industry has created their own called YD/T1591-2009. Other suppliers of high-volume devices have or are working on bespoke charging profiles.

Fast, proper rate charging from Apple, Samsung and others is essential as harried consumers increasingly rely on mobile devices more than laptops. Refer to my complaint above RE: my Asus T100.

Who has time to wait overnight?!

USB Devices Available

Pericom Semiconductor, who is sponsoring this particular blog posting, has been an innovator in USB charging devices since 2007. With a growing assurance list of charge-compatible consumer products, the company has a broad portfolio of USB ICs.