On January 10, 2006, Apple released the MagSafe power adapter. The patented design features a non-ferrous block of metal in its connector that is magnetically attracted to an actual magnet on the DC input board within your computer, similar to Japanese deep friers from the turn of the century that incorporated the magnet so the extremely hot contents would not spill if somebody tripped over a cable.
Originally, the MagSafe connector had a “T” shape that was perpendicular to the laptop. Subsequent modifications brought about the “barrel” or “L” shaped connector, a design that has frustrated consumers because it limits useable orientation to one way; if it is plugged in the other way, a port or two is covered by the wire.
Some people I’ve talked to are even more frustrated that Apple has revisited its initial “T” shaped connection on its brand new, thin, MagSafe 2 design, made to accommodate the thin form factor of their newest laptops. As a technician, I’m partial to the “T” because I can work on a laptop while it lays on its clamshell (Apple logo side), boards facing me, without straining the cable or covering the ethernet/USB ports.
If you look at a cross section of the connector, you’ll note 5 pins in a vertical array. The two outer pins are grounds in continuity with each other, the 2 in from those are 16.5V direct current, and the center is the charge control pin. The latter little guy determines what color the LED on the MagSafe connector will be: Green = charged / no battery connected, Amber = battery not fully charged, Dark = insufficient power flow, disconnected, or some other failure. It also communicates to the logic board the charger’s serial number and type of power received (for Apple computers, it’ll be 45W, 60W, or 85W depending on the model). It connects directly to a tiny circuit board you would find if you pried open the MagSafe connector.
This board has historically been provided by Maxim Integrated to Apple. The board used in my most reliable bench MagSafes is the DS2412 1-Wire protocol Addressable Switch. 1-Wire is a technology developed by Maxim Integrated that combines memory, mixed signal, and authentication in one interface, which makes your Mac’s power supply a bit smarter and more evolved than its PC brethren. This manufacturer’s ESD performance is well known in the electrical engineering community, which should give you peace of mind when practicing safe habits of surge protection, careful handling, and reasonable climate control of your computer.
In part 2, I will discuss the process that occurs when you plug the MagSafe into your computer and describe the possibilities of failure you may be experiencing beyond a dead charger. I’ll also delve into the power block itself and hopefully calm some customer worry with regards to its seemingly excessive temperature on occasion. Electronics, with so many small components working in tandem, do not always give us a simple answer when it comes to faults — but then again if they did, our lives as technicians wouldn’t be so interesting.