FDMF5804 CPU Power Stage (DrMOS) IC for MacBook

Some MacBook boards build the CPU power stage from integrated parts that combine the MOSFET driver and the switching transistors in one small package. When one of these stages fails, it often fails short, pulling the input rail down and stopping the machine from starting at all.

This listing sells the FDMF5804, sold as a CPU MOSFET chip for MacBook, in a 17-pin QFN package. It doesn't name specific models or a board position, so match it by the marking on your board.

Typical reasons to replace it

• A short on the main power rail traced to the power stage.

• The stage getting hot as soon as power is applied.

• A missing CPU rail with the controller signals present.

• Burn marks on or near the package.

Diagnosis tips

Use voltage injection and a thermal camera to find which part on a shorted rail heats up. If it's the power stage, also check the controller and the output inductor, as a failed stage can take neighboring parts with it.

Fit with flux and hot air, make sure the large ground pad is soldered, then test the rail before attempting a full boot. A stage that stays cool under load is a good sign.