MAX77843 Power IC

The MAX77843 sits at the center of power distribution on several Samsung boards. Maxim Integrated designed it as a companion PMIC for smartphones, and Samsung placed it on the Galaxy S6 (G920F), Galaxy S6 Duos (G920FD), Galaxy S6 Edge, and Galaxy Note 4 (N910F/N9100) power section. When you open a dead phone from this lineup and the board shows no charging response, this chip is one of the first components you check.Inside, the MAX77843 runs a dual-input Smart Power Path switch-mode battery charger rated at 3.0A, with reverse boost capability built in. It accepts adapter input protection up to 16V DC, so it tolerates voltage spikes from cheap chargers without failing outright — though repeated abuse still wears the die down over time. The charger switches at 4MHz, which keeps the inductor and capacitor footprint small on the board, a detail that matters when you're comparing the original part against a compatible substitute during PCB repair.Fuel gauge readings on these Samsung models come from the same chip. The MAX77843 uses Maxim's ModelGauge (mg5) technology to track battery percentage and report it to the software layer. If a technician sees battery percentage jumping erratically, sudden shutdowns at 40% battery, or wrong percentage display after a screen or battery replacement, a faulty MAX77843 is a common cause — not always a battery fault.The chip also handles two SafeOut LDOs, a four-channel RGBW driver for notification lighting, a haptic driver for vibration motor control, and a manual reset line. On top of that, it runs a customized MUIC (Micro USB Interface Controller) block that detects USB accessory type, supports USB Charging Specification Revision 1.2, and includes high-voltage adaptor detection. This is why a bad MAX77843 sometimes shows up as USB not detected, no fast charging, or accessory mode not switching, instead of a straightforward dead phone.Communication with the main processor runs over an I2C revision 3.0 compatible interface — one SDA line and one SCL line. If your ISP box or software readout shows I2C communication errors tied to the power management address, this IC is worth checking before you move to CPU-side reballing.On the repair bench, this component comes into play during dead board diagnosis, power IC replacement after liquid damage, and reballing work when the original chip shows lifted balls or cold joints under the microscope. Pull the faulty chip with your hot air station, clean the pads, reball if needed, and reflow the replacement using standard BGA rework practice. Since this is a BGA package, a stencil and proper heat profile matter more than solder quantity — rushing the reflow is the most common reason technicians report a "dead after flash" board even after installing a good chip.Stock genuine Maxim-sourced MAX77843 units on your bench instead of testing your luck with untested pulls. A verified chip saves you the callback when a customer's board still won't charge after the first attempt.