Allegro MicroSystems, a provider of power and sensing solutions for motion control and energy efficient systems, said it has launched the world’s first three-phase brushless DC (BLDC) driver IC with integrated power loss brake (PLB) features. The A89331 code-free, sinusoidal sensorless fan driver is designed to 
Source: Allegro MicroSystemsimprove thermal efficiency, which reduces energy use and data center costs. The new PLB features also improve safety and reduce the bill of materials (BoM) in data centers.
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 integrated PLB function in the A89331 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 center 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 is the world’s first and only solution that 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. Benefits include better performance, lower BoM cost, smaller footprint, reduced development cost and faster time to market.
A89331’s integrated power loss brake also stops fans from spinning when they are disconnected from power to prevent injury.
The A89331 offers a trapezoidal drive for higher RPMs and improves speed accuracy to ±1.5% at 25° C.
A89331 has maximum input voltage operating rating of 18 V with an operating range of -40° to 105° C. It is available in a 28 contact 5 mm × 5 mm quad-flat no-leads (QFN) with exposed thermal pad (suffix ES), and a 20 lead thin-shrink small-outline package (TSSOP) with exposed thermal pad (suffix LP). These packages are lead (Pb) free, with 100% matte-tin lead frame plating.
Samples of the A89331 are now available by request.
