MOSFET Controllers have on-board commutation logic.
Press Release Summary:
Targeted at automotive Hall commutated three-phase motors driven by discrete external N-Channel MOSFETs, control ICs A3930 and A3931 are temperature rated and operate with battery voltage ranging from 5.5 V to 50 V. Model A3931 provides optional pre-positioning function by driving low Hall inputs. Features include integrated charge pumps, Hall sensor voltage supply, and low current quiescent mode.
Original Press Release:
Allegro MicroSystems, Inc. Announces New Three-Phase BLDC MOSFET Pre-Driver Controller ICs
Automotive Grade MOSFET Controllers with On-Board Commutation Logic
Worcester, MA - December 19, 2007 - Allegro MicroSystems, Inc. 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. For more information on this product please click here: A3930/31
About Allegro
Allegro MicroSystems, Inc. is leader in developing, manufacturing and marketing high-performance power integrated circuits and integrated Hall-effect magnetic sensors. Allegro's innovative solutions serve high-growth applications within the automotive, communications, computer/office automation, consumer and industrial markets. Allegro is headquartered in Worchester, Massachusetts (USA) with design and applications center located in North and South America, Asia, and Europe. Further information about Allegro can be found at www.allegromicro.com.
