MagSafe is a series of proprietary magnetically attached power connectors,
originally introduced by Apple Inc. on January 10, 2006, in conjunction with
the MacBook Pro at the Macworld Expo in San Francisco, California.
The connector is held in place magnetically so that if it is tugged —
for example, by someone tripping over the cord — it will pull out of the
socket without damaging the connector or the computer power socket, and without
pulling the computer off the surface on which it is located. MagSafe works
similarly to the magnetic power connectors that many deep fryers and
Japanese countertop cooking appliances from the early 2000s have in order to
avoid spilling their dangerously hot contents.
Apple owns US Patent No. 7311526 and does not license the MagSafe connector
or the patent. Features
MagSafe has connector pins that are designed so the rectangular connector
can be inserted in either orientation. LEDs on both the top and bottom of the
connector show green if the computer battery is fully charged and amber or
red if the battery is charging. MagSafe can be found on the MacBook, MacBook Pro
and MacBook Air notebook computers, as well as the Apple LED Cinema Display.
The MacBook and the 13-inch MacBook Pro use a 60 W MagSafe charger, whereas the
15- and 17-inch MacBook Pro use an 85 W MagSafe charger. The MacBook Air has a
lower-powered 45 W version of the MagSafe adapter. The power brick is
smaller, but the MagSafe connector is the same as on the 60 W and 85 W
chargers. Apple has made it clear that an adapter with the same or higher
wattage than originally provided may be used without problems.
Apple also offers a "MagSafe Airline Adapter" for use on certain compatible
airplanes. It has a DC input and will power the computer, but will not charge
the battery. Some Apple desktop displays include a
MagSafe connector which allows charging of Apple laptops.
= MagSafe 2 = On June 11, 2012, a thinner "MagSafe 2"
connector was announced at Apple's 2012 Worldwide Developers Conference. It was
manufactured, reportedly, simply in order to fit the new MacBook Pro 15-inch
with Retina display, as well as the updated line of MacBook Air. It also has
a new connector shape based on the original one.
Apple sells a MagSafe-to-MagSafe 2 converter to allow use of older-style
MagSafe adaptors with newer Apple laptops.
Pinout The MagSafe connector pins allow for the
adapter to be inserted in opposite orientations. The first and second pins
on each side of the tiny central pin have continuity with their mirror pins.
The inner large pins are V+. Measuring with no load will give 6.86 V DC for
MagSafe and about 3 V DC for MagSafe 2; the full voltage is provided after a
~40kOhm load is applied for one second. The outer large pins are 0 V.
The tiny center pin is a data pin using the 1-Wire protocol. The computer uses
this pin to change the LED’s color and retrieve the serial number and wattage
of the power supply. Only two wires – power and ground – go
to the charger unit. There is no data communication via the adapter sense pin
with the charger unit itself. The maximum voltage supplied is as
follows: 14.5 V DC for the 45 W units supplied
with MacBook Air 16.5 V DC for the 60 W units supplied
with MacBook and 13" MacBook Pro 18.5 V DC for the 85 W units supplied
with 15" and 17" MacBook Pro 20 V DC for the 85 W units supplied with
15" MacBook Pro Retina The rectangular metal shroud surrounding
the pins has no electrical function. Rather it acts as shielding for the
electrical pins and a ferrous attractor for the magnet in the laptop.
Third-party products Although Apple does not license the
MagSafe connector for use in third-party products, manufacturers have devised a
workaround: their MagSafe items use the actual connector from Apple's AC
adapter, grafted onto their own product. Since this uses an actual Apple product,
purchased legally, manufacturers believe that no licensing agreements are needed
and the patents are not violated. However, in 2010 Apple still sued one
such manufacturer, Sanho Corporation for selling its very popular HyperMac
battery extension products which Apple claimed violated their patents. Sanho
has since ceased to sell their connector cable for the HyperMac series of
external batteries. Apple's "MagSafe Airline Adapter" cable
can power an Apple notebook computer from a 12 V DC power source, but will
not charge the battery. Apple has not sold a product with this capability, and
in the past has discouraged other manufacturers from producing such a
product. Defects
Many users have reported problems with the quality of the construction of the
MagSafe cords, giving the product low marks on the Apple Store's website.
Common complaints include plug separating from the cord, transformer
shorting, and pin springs losing elasticity.
Several methods have been devised to protect the MagSafe from failure,
including wrapping the cable with tape or sliding protective plastic around the
cable. In 2008, Apple posted an official
response acknowledging problems with MagSafe adapters, which include
incomplete circuit connection and adapter's white insulation separating
from the magnetic end of the MagSafe connector. Following the release of a
Knowledge Base article, a class-action lawsuit was filed on May 1, 2009, in the
US District Court for the Northern District of California's San Jose
office, alleging that the MagSafe power adapter is prone to frayed wires and
overheating, and as such represents a fire hazard. Apple has since released a
new connector to remedy the defects. There had been a variety of reports of
the newer MagSafe AC adapter not working with older MagSafe-powered MacBooks and
MacBook Pros. Apple released a firmware update in October 2010 that it claims
resolves this issue. However, the installer for the firmware update will
not run on certain older MacBooks, which means that the firmware can not be
updated. This, in turn, means that it is not possible to use the new MagSafe
power adapter with these MacBooks. Since mid-2010, it is not possible to buy new
replacement MagSafe AC adapters that work with these MacBooks, forcing owners
to look for used original adapters. In 2011, Apple posted a support document
about the strain-relief problems with the MPM-1-style MagSafe power cables,
and issued settlement offer for buyers of Apple 60 W or 85 W MagSafe MPM-1
adapter within the first three years of purchase.
Earlier power systems Before MagSafe, Apple laptop computers
used a shell and socket/pin arrangement, or coaxial power connector. The iBook
series introduced a charger that resembled a mini-stereo plug with an
additional metal ring. The first puck-shaped iBook chargers simply had a
silver plug body, but the square white chargers introduced a color-changing
illuminated ring that indicated charging status.
Tripping on an iBook cord or yanking the cord out at an angle could bend the
spring contacts inside the connector or break the solder pads under the
connector, resulting in a laptop that would fail to charge when connected to
the cord, or would only charge if the inserted plug were propped up or pushed
down at an angle. An especially forceful yank could flare the outer flange or
even break the tip of the power plug. Replacing a damaged "DC-In Board" in an
early 12 inch G3 iBooks typically involved an expensive 50-step
disassembly of the laptop. Gallery
References External links
"MacBook Pro". Ars Technica. , part of the Ars Technica review of the MacBook
Pro dedicated to the MagSafe connector. "Where Are the MagSafe Adapters for Cars
and Airplanes?". ZDNet. "MagSafe". Apple Inc.