{"id":12956,"date":"2015-11-30T10:11:32","date_gmt":"2015-11-30T15:11:32","guid":{"rendered":"http:\/\/mjtsai.com\/blog\/?p=12956"},"modified":"2015-11-30T10:11:32","modified_gmt":"2015-11-30T15:11:32","slug":"surprising-complexity-inside-apples-power-adapter","status":"publish","type":"post","link":"https:\/\/mjtsai.com\/blog\/2015\/11\/30\/surprising-complexity-inside-apples-power-adapter\/","title":{"rendered":"Surprising Complexity Inside Apple&rsquo;s Power Adapter"},"content":{"rendered":"<p><a href=\"http:\/\/www.righto.com\/2015\/11\/macbook-charger-teardown-surprising.html\">Ken Shirriff<\/a> (<a href=\"https:\/\/news.ycombinator.com\/item?id=10628212\">comments<\/a>):<\/p>\n<blockquote cite=\"http:\/\/www.righto.com\/2015\/11\/macbook-charger-teardown-surprising.html\"><p>This is a fantastic quote, but unfortunately it is entirely false. The switching power supply revolution happened before Apple came along, Apple&rsquo;s design was similar to earlier power supplies[4] and other computers don&rsquo;t use Rod Holt&rsquo;s design. Nevertheless, Apple has extensively used switching power supplies and pushes the limits of charger design with their compact, stylish and advanced chargers.<\/p>\n<p>[&#8230;]<\/p>\n<p>The transformer safely transmits power between the primary and the secondary by using magnetic fields instead of a direct electrical connection. The coils of wire inside the transformer are triple-insulated for safety. Cheap counterfeit chargers usually skimp on the insulation, posing a safety hazard. The optoisolator uses an internal beam of light to transmit a feedback signal between the secondary and primary. The control chip on the primary side uses this feedback signal to adjust the switching frequency to keep the output voltage stable.<\/p>\n<p>One unexpected component is a tiny circuit board with a microcontroller, which can be seen above. This 16-bit processor constantly monitors the charger&rsquo;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.<\/p><\/blockquote>","protected":false},"excerpt":{"rendered":"<p>Ken Shirriff (comments): This is a fantastic quote, but unfortunately it is entirely false. The switching power supply revolution happened before Apple came along, Apple&rsquo;s design was similar to earlier power supplies[4] and other computers don&rsquo;t use Rod Holt&rsquo;s design. Nevertheless, Apple has extensively used switching power supplies and pushes the limits of charger design [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"apple_news_api_created_at":"","apple_news_api_id":"","apple_news_api_modified_at":"","apple_news_api_revision":"","apple_news_api_share_url":"","apple_news_coverimage":0,"apple_news_coverimage_caption":"","apple_news_is_hidden":false,"apple_news_is_paid":false,"apple_news_is_preview":false,"apple_news_is_sponsored":false,"apple_news_maturity_rating":"","apple_news_metadata":"\"\"","apple_news_pullquote":"","apple_news_pullquote_position":"","apple_news_slug":"","apple_news_sections":"\"\"","apple_news_suppress_video_url":false,"apple_news_use_image_component":false,"footnotes":""},"categories":[2],"tags":[406,452,295,30,100,365,280],"class_list":["post-12956","post","type-post","status-publish","format-standard","hentry","category-technology","tag-appleii","tag-hardware","tag-history","tag-mac","tag-macbookpro","tag-magsafe","tag-power"],"apple_news_notices":[],"_links":{"self":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts\/12956","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/comments?post=12956"}],"version-history":[{"count":1,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts\/12956\/revisions"}],"predecessor-version":[{"id":12957,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts\/12956\/revisions\/12957"}],"wp:attachment":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/media?parent=12956"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/categories?post=12956"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/tags?post=12956"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}