The A89331 code-free, sinusoidal sensorless fan driver is designed to improve thermal efficiency, which reduces energy use and data centre costs. The PLB features also improve safety and reduce the bill of materials (BoM) in the data centre. When server fans malfunction or break, backflow causes them to go into reverse rotation. The other fans have to work harder to compensate for the resulting airflow, which increases power consumption.
The PLB function in the fan driver applies a brake to fans that aren’t working properly, which eliminates the extra power use and increases thermal efficiency. The end result is lower energy consumption and lower data centre costs. The traditional solution to preventing reverse rotation of broken fans is adding external circuitry to function as the power loss brake, and these external components do not fit into 1U fans. BoM cost goes up and efficiency goes down. This approach also requires coding, which increases time to market.
The A89331 fits both a three-phase BLDC driver and PLB in a 1U fan. Plus, Allegro’s proprietary code-free drivers eliminate the need for software development and verification. It offers a trapezoidal drive for higher RPMs and improves speed accuracy to ±1.5% at 25ºC. The chip has a maximum input voltage operating rating of 18V with an operating range of -40 to 105°C. It is available in a 28-contact 5×5mm QFN with exposed thermal pad, and a 20-lead TSSOP with exposed thermal pad.
Allegro MicroSystems - www.allegromicro.com