Design reliability; Case Study: Chinese Apple Power supply

amirm

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Apr 2, 2010
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Most of our discussions in forum are about best performance. But engineering is also a lot about reliability and safety to user. There was news this week that someone had died in China from an "Apple" charger on iPhone 4. Latest news seems to indicate the charger in use was a counterfeit charger. It is remarkable how far they go in making the units look the same. But the guts inside are a different story.

This video is from Dave Jones whose video blogs are a jewel for electronic engineers/hobbyist where he takes apart these chargers. So it may be a bit too technical as far as the points he makes but it is still a very good watch given the latest news on this front:


Safety is a big issue here since to make these chargers small, they use a switching power supply. A switching power supply converts the input AC to DC, converts it to high-frequency AC as to make stepping it down in voltage much smaller. Otherwise, you would need the large, heavy traditional transformers. The transformers are great because they provide high isolation so even cheap ones aren't so bad. Cheap switching power supply is another matter since DC high voltage is so close to the USB output. Watch the video above which should scare the pants off of anyone using knock off chargers.
 

amirm

Banned
Apr 2, 2010
15,813
37
0
Seattle, WA
http://news.cnet.com/8301-13579_3-5...ath-in-china-could-be-linked-to-fake-charger/

iPhone-related death in China could be linked to fake charger
The reported electrocution of an iPhone owner in China last week is now said to stem from the use of a faulty third-party charger.

The death of a 23-year-old Chinese woman last week, who was allegedly electrocuted while answering a call on her iPhone, is now believed to be linked to a third-party USB charger.

Ma Ailun was apparently using a third-party charger with her iPhone 4, instead of one made by Apple. That's according to Xiang Ligang, a phone expert interviewed by CCTV earlier this week (Google translation), who suggested that the charger may have had fewer safety measures built into its hardware, and experienced a failure.

The incident, which is still being investigated by both Apple and local authorities, was originally believed to involve an iPhone 5 -- Apple's latest model. However the device in question was Apple's iPhone 4, which was released in mid-2010, CCTV said.

Third-party chargers are commonplace for electronics, and often come at a steep discount compared to the ones technology companies sell. However, when it comes to the knockoffs -- the ones designed to cosmetically look like the real thing -- consumers can't be certain of their safety

Last October, Googler Ken Shirriff tested a dozen USB chargers -- from the real to the counterfeit -- and found wide gaps in both the quality and safety of those devices. Safety science company UL also issued a warning to consumers and retailers about counterfeit Apple USB power adapters making the rounds back in March.

CNET has contacted Apple for additional information, and will update this post when we know more.

(via South China Morning Post)
 

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