Worcester, Mass. Allegro MicroSystems, Inc. has introduced two automotive-grade (temperature and voltage rated), three-phase BLDC motor controller integrated circuits. These A3930 and A3931 control ICs are said to simplify system design and lower system cost by integrating the commutation logic on-board, which reduces the burden on the system microprocessor.
If desired, the Hall sensor inputs can be driven directly by a microprocessor, which makes the A3930 and A3931 key components in a BEMF (sensor-less) solution, said Allegro. These controllers are primarily targeted at automotive Hall commutated three-phase motors driven by discrete/external N-Channel MOSFETs.
An on-chip commutation decoder and state machine reads the inputs of three Hall sensor inputs (or IO outputs from a microprocessor). The IC outputs the correct gate drive signals that control six (three high-side, three low-side) external NMOS MOSFETs, which drive the three-phase BLDC motor.
Other key features incorporated on the IC include 5-V supply for Hall sensors (requires external NPN transistor), integrated charge pump, operation over a wide battery voltage range (5.5 V to 50 V), extensive diagnostics, and low current quiescent current mode.
The A3931 is a minor modification of the A3930. In the A3931 an optional pre-positioning function is possible by driving the three Hall inputs low. This provides for a known start-up position for the motor by forcing a position between two detent positions. This start-up condition aids any algorithms that may be utilized with the IC (such as sensorless BEMF commutation schemes), said Allegro. The A3930 and A3931 controller ICs are offered in a small thermally efficient 48L eLQFP package.
Pricing: $3.12 each in quantities of 1,000.
Availability: Two-week typical delivery.
Product information: A3930/A3931
Allegro MicroSystems, Inc., www.allegromicro.com