Motor control is becoming a huge market, driven by energy saving demands in consumer products and the growing use of small motors in autos. Microchip Inc. is the latest company to jump on this bandwagon, unveiling a microcontroller with peripherals tailored to motor control.
Automotive engineers are using motors in fuel pumps, for positioning seats, and to improve ventilation, while consumer product engineers are striving to reduce power consumption to meet Energy Star requirements.
In both environments, quieter operation is one of many factors fueling a boom for chipmakers. "With motor control, there are many ways to reduce power, and you can eliminate belts and gears to lower costs. You can also eliminate clunky starts by ramping up slowly to reduce noise," says Cheri Keller, product marketing manager at Microchip's Advanced Microcontroller and Automotive Division in Chandler, AZ (http://rbi.ims.ca/3846-533). Appliances are the key target market, followed by automotive and industrial applications, she adds.
Age of specialization
Designers like the simplification that the focused controllers bring. "Typically, we have short development times for systems that might see changes in motors, so we need a board that can be adapted. It's nice to have something that you can quickly tune and adapt to different motors," says Fred York, a staff engineer at Sparton Corp., a Jackson, MI contract design and engineering house.
York specializes in medical applications that typically require 32-bit devices, but notes that 16-bit chips can be used in many applications to trim costs. "Resolution is really the secret, you have to know what the performance must be. The chip has to be able to read the speed and position. If you don't do that in the chip, you're going to have to add circuitry to handle that," York notes.
Other chipmakers are responding with products that typically cost less than $10. Philips Semiconductors of San Jose, CA, targeted motor control when it introduced its LPC21xx, a $5 Arm 7 processor core, last fall (http://rbi.ims.ca/3846-534). Motorola unveiled its approach at about the same time, coming out with the 56F8300, a microcontroller with DSP that includes components needed for motor control (http://rbi.ims.ca/3846-535), again at pricing below $10.
"The 8- and 16-bit manufacturers are working hard to bring costs down, trying to get into applications that have a lot of mechanical controls. Consumer applications are key, because they have high volumes, and motor control doesn't have the level of processing power that will drive users to 32-bit chips," says Tony Massimini, chief of technology at Semico Research of Phoenix (http://rbi.ims.ca/3846-536).
Microchip's device, the PIC18F, costs from $4.50 to $5 in OEM quantities dropping to around $2 in very high volumes. The line offers three peripherals used in many motor control systems. Its power control module has a three-phase pulse width modulation structure, handling up to eight PWM channels with 14-bit resolution and center alignment. A quadrature encoder interface is included in the motion feedback module, while a 200 ksamples/sec analog-to-digital converter rounds out the motor control features.
"The 200 ksample rate is one of the fastest in the industry," Keller says. She adds that the device has low power consumption, in the nanowatt range, addressing another need for both portables and hardware that operates plugged in. A clock monitor provides fail-safe operation in the event of clock failures.
These motor control chips also handle some motion control functions, but they typically only handle one axis of motion. Therefore, the ICs aren't expected to have much of an impact on the many firms that sell motion control systems, which are typically far more complex. "We have many axes of motion that require 32-bit processors. Our customers typically don't want to build their own systems," says Lisa Wade, spokeswoman at Galil Motion Control Inc. (http://rbi.ims.ca/3846-537).
Motion control companies typically design boards for complex, comparatively low volume products such as semiconductor processing equipment. Chipmakers are addressing a vastly different market. "The chips are a great solution for high volume designs that are comparatively simple," Wade adds.
Though the chips are at the low end of this marketplace, they're not aimed at simple applications. In simple tasks like moving vehicle windows or mirrors, motors can be controlled by very inexpensive, 8-bit, 8-pin processor chips often mounted on the motors. The more powerful 16- and 32-bit devices now in the marketplace are aimed at applications with greater demands. "These devices have 28-40 pins. Often, they will communicate with other chips," Keller says. For example, an auto's fuel pump needs to communicate with other power train controllers. These chips may also handle other tasks such as measuring temperature, she adds.