Most people view the power adapters for their laptops as comparatively dumb devices that they can't find, can't get to work or struggle to untangle -- but a look into the charger for Apple Inc.'s MacBook laptop reveals a surprising level of complexity and a microprocessor that is more powerful than the one that was inside the original Apple Macintosh computer.
The fact power adapters even need a microprocessor chip will be news to most people, but one software engineer has discovered that among the plethora of components that go into making up a modern laptop charger is a 16-bit microprocessor. Ken Shirriff, a software engineer at the Google unit of Alphabet Inc., had decided to find out exactly what was contained within Apple's 85W MacBook charger when he made the surprising find.
"One unexpected component is a tiny circuit board with a microcontroller," Shirriff said on his Righto blog. "This 16-bit processor constantly monitors the charger's voltage and current. It enables the output when the charger is connected to a MacBook, disables the output when the charger is disconnected and shuts the charger off if there is a problem. This processor is a Texas Instruments MSP430 microcontroller, roughly as powerful as the processor inside the original Macintosh."
As Shirriff explained, most of the weight of the power adapter comes from the multiple metal heat sinks employed by Apple to distribute the heat and cool the high-powered semiconductors inside the charger. However, there are a lot of other components inside the official, original charger, including capacitors, diodes, transistors and transformers. A comparison between it and an unofficial, imitation charger showed just why buying one of the former may be wiser than purchasing one of the latter.
While an official Apple charger will cost you $79 direct from the company, you can pick up third-party chargers through Amazon.com and other online retailers for as little as $14 each. Shirriff decided to investigate just what you were getting for what appears at first to be a bargain price. "From the outside, the charger looks just like an 85W Apple charger, except it lacks the Apple name and logo. But looking inside reveals big differences."
As you can see in the images above, the difference on the inside is stark. "The imitation charger has about half the components of the genuine charger and a lot of blank space on the circuit board. While the genuine Apple charger is crammed full of components, the imitation leaves out a lot of filtering and regulation as well as the entire PFC circuit," Shirriff said.
However, the engineer did admit that the makers of the imitation charger "didn't cut every corner possible" and "use a moderately complex circuit" and that they are nowhere near as dangerous as the imitation iPad and iPhone he has investigated in the past. He also said that while Apple's charger does have a huge number of additional components, these would add maybe $15 at most to the cost and that the huge disparity in prices has more to do with Apple's notoriously high margins than anything else.
Meanwhile, Apple's fully packed chargers have not gone down too well among those who have bought it, getting a rating of just 1.5 out of 5 in the company's online store, with one reviewer calling the device "a danger to my family" and saying the family is now on its third unit: "The first one overheated to the point of melting the wire. On the second one, it still heats up a lot and the wire has deteriorated at the connections on the adapter side as well as the magnetic-connection side. I have put electric tape on both ends, but now it is starting to spark when connected to laptop."