To USB or Not to USB


USB Type-C: More Power – Part 1

USB Type-C makes USB so awesome you can read about how it makes the world a greener place in Scientific American.

Or you can read a dazzlingly scintilating article here

(The meat of this article is below this section, and before the Elephant Jokes, so skip this section if you don’t care about the history of USB power and it’s problems.)

USB Charging before USB 3.1 (That means USB 3.1 Gen 1 or USB 3.0 Reborn)

USB 3.0 doubled the amount of power you could draw from 500mA at 5V to 900mA at 5V, or from 2.5W to 4.5 W.

Okay almost doubled

The best feature with 4.5W: With 4.5W you could power up and spin a DVD drive or a hard drive without a separate power cable.

Pretty neat.  This enabled the sale of portable terabyte hard drives that you could back up your entire (mostly) legally obtained digital content and carry it around with you.

With falling prices of NAND flash for SSDs and thumb drives, it will all be SSDs, so you don’t need the power any more.


You can use 3.0 power to power portable LCD screens

These (by the way) use a DisplayLink chip which just happens to use Synopsys USB 3.0 controller and PHY IP.

AOC USB 3.0 Powered Monitor with DisplayLink chip inside

See more products like this here:

The problem with USB power with USB 2.0 and USB 3.0

For power the biggest problem with both USB 2.0 and USB 3.0 reborn is the power provided is not/was not guaranteed.
If you plugged a USB peripheral into a host (a PC, game system, or TV) there was no guarantee of the power provided.  Only the possibility.

On the other side, many (possibly most) hosts had no control (or didn’t regulate) how much power a peripheral could draw.  It could be possible for mobile phone charging from a laptop host port, could fast charge and drain the laptop battery rapidly by drawing more power than it should even based on USB standards.  At the same time, a smart laptop maker could reduce the power draw or regulate it to protect the battery.

USB Type-C starts down the path of fixing this.


To subscribe, click on this link:

USB 3.1 Gen 2 Type-C

For USB Type-C, the power is now 3x (actually 3x this time) more than USB 3.0.

Power is guaranteed to be 7.5 Watts or 15 Watts. (This is up from the 4.5W of USB 3.0 Reborn)

This is from the increased amperage at the same 5 V, so 1.5 A or 3.0 A at 5V.

This is a bunch of power.  It means your mobile phone, tablet, or PC could charge faster.

So you might ask: My PC only needs 15W?

The answer is we can expect continued convergence between tablets and PCs, with processors needing/using less and less power.  The iPads and tablets of today actually only charge at 5-10W.  So with 15W, they charge even faster.

The point is, Type-C can be used to charge and drive the bulk of devices people use today.

And will continue to be useful as we build more power efficient products.

Power with Type C and PD

Part 2 will be after Mick Posner’s Epic blog entry next week. Possibly after 2 of Mick’s Epic Blogs.

USB 5.0 Today’s Elephant Jokes

Q: What do you get if you cross an elephant with a kangaroo?
A: Big holes all over Australia.

Q: What kind of elephants live at the North Pole?
A: Cold ones.

Q: What’s convenient and weighs 20,000 pounds?
A: An elephant six-pack.

Q: How do elephants talk to each other?
A: By ’elephone.

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