The CD3217B12 sits at the center of USB-C power delivery on modern Apple boards. Texas Instruments builds it as a customized version of its TPS6598x Type-C Port Switch and Power Delivery controller family, and repair technicians commonly refer to this Apple-specific line as the ACE2 controller (short for Apple Charging Engine). You will find it printed on the board as U3100, with dual-port designs sometimes carrying a second unit at U3200. Package markings on the chip itself also appear as CD3217B12ACER, CD3217B12BCE, or CD3217B12GACER depending on the batch and board revision.On the board, the CD3217B12 works alongside companion parts such as UF400 (master port switch) and UF500 (slave port switch) to route power and data through the USB-C connector. When a charger connects, the controller handles the PD handshake — negotiating voltage and current with the adapter, then instructing the battery charger IC (commonly a Renesas ISL9240 on recent MacBook boards) to accept the negotiated power. This places the CD3217B12 squarely in the charging and power delivery workflow rather than the battery management or display circuits, so its failure symptoms are almost always charging-related rather than boot or display faults.The most reported symptom of a failing CD3217B12 is a board that charges at 5V only, instead of pulling the full 9V/15V/20V profile a compatible charger and cable can supply. Some boards show a dead port entirely — plugging in a charger produces no response at all from that connector, while the second port (if present) may still work normally. Because the controller also handles port switching, a faulty unit can sometimes cause data or display-over-USB-C issues on ports that share Thunderbolt/USB-C functionality, though the charging symptom is far more common in repair shop diagnostics.Board-level replacement of the CD3217B12 requires BGA rework — hot air removal, pad cleaning, and reballing with the correct ball pitch before reflow. This is not a chip a technician swaps casually: revision matching matters. Apple firmware and board configuration differ between CD3217B12, CD3217B13, and CD3218B12, so using the wrong revision on a board can leave the port non-functional or cause abnormal charging behavior even after a clean reflow. Before ordering a replacement, confirm the exact revision printed on the donor board or the original failed chip, and cross-check I2C addressing from the board schematic if you're working blind without a donor reference.This IC covers a wide range of Apple hardware built between 2018 and 2021, spanning MacBook Pro 13-inch and 16-inch models, M1 MacBook Air boards, and several generations of iPad Pro and iPad Air tablets that use USB-C charging. For a repair shop handling mixed Apple board work, stocking the CD3217B12 alongside its paired UF400/UF500 switches covers a large share of "charges at 5V" and "dead port" tickets that come in weekly. Pair this IC with a quality hot air station and BGA stencil kit sized for the correct ball pitch to keep first-attempt reflow success high and avoid repeat callbacks from cold joints or shifted balls.
