Delete comment from: Ken Shirriff's blog
Hi Musashi! Identifying the chip was hard. I assumed it was a custom 1-wire protocol chip, so I sent it random 1-wire commands to see if I could figure it out, without success.
Then I looked at the datasheets for some existing 1-wire chips to figure out what style of commands they used. When I looked at the DS2413 chip, I thought Doh! that's the obvious chip to use to control 2 LEDs, since it has two switches. When I sent the DS2413 commands to the chip, it responded just like a DS2413, which makes it pretty clear that the chip is a DS2413.
Then, I found that chips with custom IDs add hex 80 to the family code, so the charger's family code of BF is really hex 3F, which you can look up on the 1-wire family code list, and 3F is the DS2413's family code. If I realized that originally, I could have saved myself a lot of originally.
Jun 7, 2013, 9:36:39 PM
Posted to Teardown and exploration of Apple's Magsafe connector