Brad Ideas - Steps closer to more universal power supplies - Comments

USB

brad — Mon, 28 Jan 2008 22:05:00 -0800

USB only gives 2.5 watts, though some people put 5 watts (1 amp) through it in cell battery chargers.

The goal is a data protocol on top of the power, so that the endpoints negotiate voltage and current, thus no risk of damaging parts.

Not quite as good, but still better, would be something like the tips on universal power supplies, where the tip tells the power supply what voltage to use. One could imagine notebook vendors having a power plug which is actually the master 4 or 5 wire connector of one of the tip systems, and telling people "Just get a standard universal power supply. We don't provide one." I would not be too upset because it meant that I could now share powers supplies with others, use stations that provided the universal power, and use the supply I do buy with my next computer, too.

Tip shape still not a great indicator...

Dean Landolt — Mon, 28 Jan 2008 14:15:57 -0800

I've blown out a brand new HP battery by using a brick with an identical tip that ultimately had a different power profile. I've also caught Dell doing this as well. I share your dream of universality, but I think you'd have to take a different tack. If a universal connector with a globally identifiable shape could be developed, then perhaps someone could sell tips that convert into this universal format, and eventually, maybe even manufacturers will actually start respecting it...

Hell, perhaps usb _is_ this universal format. Motorola and others are using it for cell phones, but the mini variety would never cut it for laptops. Perhaps the larger usb could handle the load, but I doubt it. It would be nice though...

Steps closer to more universal power supplies

brad — Sat, 12 Jan 2008 15:33:14 -0800

I’ve written before about both the desire for universal dc power and more simply universal laptop power at meeting room desks.

Today I want to report we’re getting a lot closer. A new generation of cheap “buck and boost” ICs which can handle more serious wattages with good efficiency has come to the market. This means cheap DC to DC conversion, both increasing and decreasing voltages. More and more equipment is now able to take a serious range of input voltages, and also to generate them. Being able to use any voltage is important for battery powered devices, since batteries start out with a high voltage (higher than the one they are rated for) and drop over their time to around 2/3s of that before they are viewed as depleted. (With some batteries, heavy depletion can really hurt their life. Some are more able to handle it.)

With a simple buck converter chip, at a cost of about 10-15% of the energy, you get a constant voltage out to matter what the battery is putting out. This means more reliable power and also the ability to use the full capacity of the battery, if you need it and it won’t cause too much damage. These same chips are in universal laptop supplies. Most of these supplies use special magic tips which fit the device they are powering and also tell the supply what voltage and current it needs.