Delete comment from: Ken Shirriff's blog
I've been an EE since 1979. Have seen the transition from the old transformer based linear discrete voltage regulator power supplies to today's modern switching/transformerless designs and their variants. While there are benefits as to size and weight in the new designs vs those of just 30 yrs ago I am still concerned about having this much circuit-density on a very small PCB inside of a sealed wall-wart case. Specifically with regard to external powerline surges and lightning strikes. Do they have a fuse? PTC's can short and fail in some circumstances. Also the ever-present threat of dubious quality counterfeit components from China. I have seen commercial service PS units and related sub-assy's fry and flame-out because of what turned out to be a counterfeit cap or off-brand semiconductor IC that failed in service, usually due to overheating from fab material degradation over time under load. I guess the rule is use prudent precautions and common sense when dealing with anything that's plugged into the 125VAC wall socket. Not only for the powered device but the infrastructure as well. You usually get what you pay for. Get the better stuff for peace of mind. A very well done and concise article!
Jul 28, 2013, 11:33:31 PM
Posted to A dozen USB chargers in the lab: Apple is very good, but not quite the best