Single-chip BLDC fan driver with I²C bus control
The MAX31790ATI+T is a fully integrated driver for brushless DC (BLDC) fan motors, combining the control logic and power stage in one 28-TQFN package. It accepts a 3V to 5.5V supply rail and communicates over an I²C interface, making it a drop-in solution for fan trays in servers, telecom enclosures, and industrial equipment where the microcontroller already has a spare I²C bus. Six low-side outputs drive the BLDC phases directly — enough for a single three-phase fan with headroom for a second fan or for multi-phase designs. The on-chip power MOSFETs eliminate external FETs, saving board area and BOM cost.
Package, footprint, and thermal management
The datasheet layout recommendation calls for a 3×3 via pattern with 0.3 mm drill — without it the junction temperature rises above the 125°C absolute maximum under continuous full-load current. Store the reels dry: the MSL rating for this package is typically Level 3, so a bake before reflow is needed if the seal is broken and the floor life is exceeded.