I'm about to change my power adapter's cable due to the classic cable fraying.

However, according to this, there's data that gets passed around using the 1-Wire protocol.

I only see 2 wires on there.

Is the cable a "smart" cable with a built-in IC, or are all logic and data pieces in the charger brick itself?

2 Answers 2


The charger's serialization and capabilities are determined by the chip in the Magsafe connector. The Mac also controls the LED, not the charger.

Understanding the charger's ID code

You can easily pull up the charger information on a Mac (Go to "About this Mac", "More Info...", "System Report...", "Power"), but much of the information is puzzling. The wattage and serial number make sense, but what about the ID, Revision, and Family? It turns out that these are part of the 1-Wire protocol used by the chip inside the connector.


There's no built-in IC inside the cable. All the logic behind the 1-Wire protocol happens inside the computer, the charging brick and the MagSafe connector.

You can see a teardown of the MagSafe / MagSafe 2 connectors on the link below, where the actual communication process is also explained:


  • This is incorrect. Source: righto.com/2013/06/teardown-and-exploration-of-magsafe.html Commented Aug 26, 2019 at 14:04
  • 2
    Well, I was thinking that the OP is interested in repairing the cable due to fraying. The chip is inside the connector, not the cable. So it is correct that there is no IC inside the cable itself - so if you want to cut out part of the cable to remove the fraying, there's no problem in that.
    – jksoegaard
    Commented Aug 26, 2019 at 14:28

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