Worcester, MA – December 19, 2007 – Allegro® introduces two new automotive grade (temperature and voltage rated) three phase BLDC motor controller integrated circuits. These control ICs greatly simplify the system design and lower system cost by integrating the commutation logic on-board, which lessons 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 robust BEMF (sensor-less) solution. 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 then 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 are: 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.

Allegro's 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).

The A3930 and A3931 are offered in a small thermally efficient 48L eLQFP package. They are both priced at $3.12 in quantities of 1,000 and have a 12 week typical lead-time to market.