Sensorless motor control is attractive proposition for OEMs for two reasons: it eliminates the need for a shaft feedback sensor, thus shrinking both the BOM and costs; and it simplifies mechanical installation at the motor itself. Until recently, however, implementing sensorless design has been a challenge, as it requires digital-processing power, carefully tuned algorithms, along with MOSFET drivers and the MOSFETs themselves, so the IC portion has been relatively costly while the associated user effort is high.
As a result, sensorless designs have not been able to work their way down into lower-cost consumer and mass-market applications, despite the motor-control market being an area of strong interest for energy efficiency and improvement, as analyzed in the IHS report, "Motor Controls Market Revives This Year After 2012 Decline."
The DRV10983 IC from Texas Instruments is designed to change that situation. This three-phase sensorless motor driver with integrated power MOSFETs can provide drive current up to 2 A (continuous)/3 A (maximum), targeting cost-sensitive applications as a result of its performance features, high level of integration and low external-component count. It requires no external sense resistor although the user can add one to monitor power delivered to the motor, if desired.
The motor driver also addresses a major shortcoming of many sensorless BLDC-drive implementations: the fast-switching (commutation) control of the motor phases generates relatively high levels of acoustic noise. While this may not be an issue in industrial installations, it's unacceptable for the consumer. To counter this problem, the device includes a proprietary back-electromotive force (BEMF) control scheme along with pure sinusoidal (180°) drive commutation and advanced start-up algorithms. This results in motor operation which is 75 percent quieter than competitive approaches, and with no clicks or pops at start-up. Further, annoying "pure tone" harmonics, which are a significant noise factor in fan applications, are reduced by as much as 25 dBA.
The motor can be controlled directly through PWM, analog, or I2C inputs. Users of this IC do not have to become familiar with complex microcontroller coding or motor knowledge. Instead, they can fine-tune its algorithms for optimal performance and reliable start-up across a wide range of motors via simple register settings.
To add to its versatility, the DRV10983 has an integrated buck/linear regulator which efficiently steps the supply voltage down to either 5 or 3.3 V (100 mA) for powering internal and external circuits. The regulator keeps running and is able to power an external microcontroller even when the DRV10983 is in its low-power standby mode.
Further, all active devices which handle power need protection against internal and external faults and transients, and the DRV10983 is no exception. Therefore, to eliminate the need for the user to add discrete protection components, it includes protection against anti-voltage surge (AVS), over-voltage, over-current, over-temperature, shoot-through, under-voltage lock-out, thermal overload, and even rotor lock.
The DRV10983 three-phase sensorless motor driver with integrated power MOSFETs is available in a 24-pin, 8-mm × 6-mm HTSSOP package and is priced at $1.19 (1,000-unit quantities). To accelerate design-in and use, TI also offers an evaluation module which includes a BLDC motor, graphical user interface (GUI), schematics, and Gerber files for $99.