338S1251-AZ (U1202) Power IC

Every iPhone motherboard runs on a power management architecture built around two main ICs, and on the iPhone 6 and iPhone 6 Plus, U1202 is the larger of the two — technicians usually just call it the "big power IC." Its factory marking reads 338S1251-AZ, and it sits in a 267-pin BGA package soldered directly onto the logic board. This chip is responsible for regulating and distributing voltage rails to the CPU, baseband processor, and several other power-dependent sections of the board, which makes it one of the first components you check when a device won't power on at all. If you work on iPhone 6 or iPhone 6 Plus boards regularly, you already know how often this IC shows up as the root cause of a dead phone. A board that pulls zero current, one that shorts immediately when connected to a DC power supply, or one stuck in a boot loop right after the Apple logo often points straight back to U1202. Before jumping to reball or replace the chip, isolate the power rail with your bench supply and current meter — a healthy board should draw a predictable current pattern on power-up, and any sudden spike or complete absence of draw narrows the fault down to this section fast. Reballing or swapping this IC is standard board-level repair work, not a beginner task. You're dealing with a dense BGA footprint, so a hot air rework station with accurate temperature control, a reballing stencil matched to the 267-pin layout, and quality low-temperature solder paste are non-negotiable. Rushing the reflow or using inconsistent heat across the pad array is what causes cold joints and repeat failures — the kind of comeback job that eats into your workshop's reputation. Preheating the board evenly before hitting the IC directly reduces thermal shock to surrounding components, especially the smaller capacitors packed close to the power section. Dead after flash cases are another common scenario where this IC gets flagged. A device that was working before a software update or restore, then goes completely dead afterward, sometimes points to a power delivery fault rather than a software issue — worth ruling out with a multimeter check on the affected rails before assuming it's purely a flashing problem. Charging issues, where the phone shows the charging symbol but never actually charges, or where current draw during charging looks abnormal, also trace back to this chip on a fair number of boards. Sourcing a reliable 338S1251-AZ matters as much as the reballing technique itself. A chip with an unclear origin or one that's been reworked improperly before reaching you can carry hidden damage that only shows up after you've already invested time reflowing it onto the board. For a workshop running through multiple iPhone 6 series boards weekly, keeping verified stock of this IC on hand cuts down diagnostic-to-repair turnaround, which matters when customers are waiting on their device. This part is intended for use by trained mobile repair technicians with BGA rework experience. If you're setting up a dedicated iPhone power section repair workflow, pairing this IC with a matched reballing stencil and a stable hot air station gives you a repeatable process instead of one-off fixes.