Delete comment from: Ken Shirriff's blog

rew said...

There is no reason for a powersupply to HAVE a constant-current mode. A charger rated at say 1.0A, could provide a straight constant-voltage line up to 1.2A and then shut down entirely.

The problem is, you'll never supply the startup-current of a few capacitors on the output this way.

But a powersupply could be designed to provide say 1.1A constant current at powerup, and switch to constant-voltage mode once 5V is reached. From then on it will shutdown when 1.2A is touched...

Anyway, in practice you're right, most have a constant-current phase leading up to the "overcurrent shutdown".

Oct 31, 2012, 9:28:21 AM

Posted to A dozen USB chargers in the lab: Apple is very good, but not quite the best