Two of the largest components in the charger are the inductor and PFC capacitor that help boost the voltage to about 380 volts DC. The PFC circuit uses a power transistor to precisely chop up the input AC tens of thousands of times a second contrary to what you might expect, this makes the load on the AC line smoother. Regulations require larger chargers to use a technique called power factor correction so they use power more evenly. If too many devices do this, it causes problems for the power company. One problem with simple chargers is they only draw power during a small part of the AC cycle. The next step in the charger's operation is the Power Factor Correction circuit (PFC), labeled in purple. The diode bridge rectifier is attached to the metal heat sink with a clip. The input components in a Macbook charger.
#NEW APPLE MACBOOK CHARGER SERIAL NUMBER#
The picture below shows several features that can help distinguish the charger from counterfeits: the Apple logo in the case, the metal (not plastic) ground pin on the right, and the serial number next to the ground pin.
Nevertheless, Apple has extensively used switching power supplies and pushes the limits of charger design with their compact, stylish and advanced chargers.įor the teardown I started with a Macbook 85W power supply, model A1172, which is small enough to hold in your palm.
The switching power supply revolution happened before Apple came along, Apple's design was similar to earlier power supplies Īnd other computers don't use Rod Holt's design. This is a fantastic quote, but unfortunately it is entirely false. Every computer now uses switching power supplies, and they all rip off Rod Holt's design." Rod doesn't get a lot of credit for this in the history books but he should. "That switching power supply was as revolutionary as the Apple II logic board was. The introduction of a single-chip power supply controller in 1976 made switching power supplies simpler, smaller, and cheaper.Īpple's involvement with switching power supplies goes back to 1977 when Apple's chief engineer Rod Holt designed a switching power supply for the Apple II. In the 1950s, switching power supplies were complex and expensive, used in aerospace and satellite applications that needed small, lightweight power supplies.īy the early 1970s, new high-voltage transistors and other technology improvements made switching power supplies much cheaper and they became widely Switching power supplies are now very cheap, but this wasn't always the case. The switching power supply gets its name because it switches power on and off thousands of times a second, which turns out to be a very efficient way to do this conversion. Most consumer electronics, from your cell phone to your television, use a switching power supply to convert AC power from the wall to the low-voltage DC used by electronic circuits. Many electronic components work together to provide smooth power to your laptop.
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