New ST7MC microcontrollers, based on industry-standard 8-bit core, include flexible BLDC motor control peripheral; plus Flash memory, 10-bit ADC, five timers, power supply management.
At Embedded World 2004, STMicroelectronics announced an extension to its ST7 family of 8-bit microcontrollers with the launch of the ST7MC 8-bit microcontroller family, specifically intended for the control of three-phase induction and permanent magnet brushless motors (including compressors).
The result of close cooperation between ST and its key appliance, automotive and industrial customers, ST says its integrated 8-bit approach offers many advantages over more costly and more difficult to implement DSP-based control solutions. The ST7MC devices feature ST's on-chip motor control peripheral, the MTC, which consists mainly of a 3-phase pulse width modulator multiplexed on six high-sink outputs, with a highly flexible back EMF (BEMF) zero-crossing detector and co-processor unit for the sensorless control of permanent magnet brushless direct current (BLDC) motors.
According to the company, its patented 'three resistors' sensorless control method - in conjunction with on-chip comparators, op-amp - provides the lowest possible system cost and the highest system integration for BLDC motor control. The MTC's input pins can also be configured for Hall, tachometer or encoder sensing. In addition, comprehensive filters and settings allow the control of any star or delta wound motor, from 12 to 240 V, in various control topologies (six-step/sine wave, current/voltage, PAM/PWM).
In a typical brushless motor design based on the ST7MC, some 70% of the CPU's resources remain free for the rest of the application as a result of the MTC peripheral handling the detailed motor control functions, says ST. The device can therefore handle both motion and upper layer functions, opening up new capabilities compared to classical three-phase brushless solutions. Furthermore, its versatility makes it the ideal platform for designers working with multiple motor control topologies.
A Starter Kit (ST7MC), a full featured evaluation and development tool, provides both a demonstration of ST7MC capability and a short-cut development platform for target applications.
For more information contact Simon Churches, Arrow Altech Distribution, 011 923 9600, [email protected]
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