Six low-side outputs drive a BLDC fan directly
The MAX31790ATI+: The driver integrates both control logic and power MOSFETs in a single 28-TQFN package. The six low-side outputs handle the six-step commutation for a brushless DC fan motor — no external FETs or Hall-effect commutation logic needed on the board. Communication with the host controller runs over an I²C bus — speed setpoint, tachometer readback, and fault flags all travel on the same two wires. Supply voltage spans 3V to 5.5V, so it works on a common 3.3V or 5V fan-tray rail.
28-TQFN with exposed pad — board layout matters
The 28-WFQFN package with exposed pad measures 4x4 mm. Shipped in a tube — not reel or tray. If the tube has been sitting in a humid environment, a bake before reflow is worth the time, same as any moisture-sensitive QFN.