ZiLog: MCUs stress level of integration, fast ADC for motor control

By Control Engineering Staff October 27, 2005
ZiLog’s FMC16100 Series microcontroller features 20 MHz CPU core, 6-channels of 12-bit PWM with fast shutdown, and 8-channel 2

Microcontroller (MCU)-based systems for motor-control applications continue to grow. One recent advance is ZiLog Inc.’s launch of new generation Flash MCUs targeting sensorless brushless dc (bldc), ac induction, and switched-reluctance motor applications. Named Z8 Encore! MC Series, the new 8-bit chips are based on extensive research into customer requirements in this rapidly growing market sector, according to ZiLog. Initial offerings provide a choice of 16 KB (Z8FMC16100), 8 KB (Z8FMC08100) or 4 KB (Z8FMC04100) of flash memory.

Addressing design challenges of advanced motor-control systems and architectures, Z8 Encore! MC family integrates numerous on-chip features and peripherals that eliminate cost of external components. “[The new family of microcontrollers] will help solve engineering challenges, such as fast over-current detection and fault control, reliable operation, and back-EMF sensing at a wide range of speeds including very low speeds, along with extremely smooth start-up and reversal of the direction of rotation,” says ZiLog chairman and CEO James Thorburn. “The new devices have been well received during early customer trials.”

Z8FMC16100 (highest performance chip) brings key benefits of improved performance, more scalability, and lower system cost to motor control applications. For example, the chip handles operation at slower motor speeds seamlessly, thereby reducing power consumption and increasing energy efficiency. To allow accurate speed control, the on-chip analog-to-digital converter (ADC)—which includes a “time stamp” feature (said to be unique)—is coupled to the 3-phase PWM output module. Moreover, advanced integrated analog modules allow for current sampling, as well as “on-the-fly” implementation of torque or speed control, according to ZiLog.

To guard against electrical noise (often generated by the motor) that can interfere with MCU operation, Z8 Encore! MC microcontrollers apply very robust chip design and use a highly accurate Internal Precision Oscillator as the system clock source (one of several clock options). Users have the option to add more complex and differentiating features. Seventeen general-purpose I/O points allow for incorporating various new system functions. Also, the new chips offer multiple, integrated communication peripherals (I

Ken Johnston, ZiLog technical product manager, told Control Engineering that high level of integration and fast A/D conversion were two main strengths of these MCUs. Johnston also emphasized “integrated in the hardware” peripheral functions (such as an operational amplifier) rather than functions integrated in software, as in competing products. ZiLog regards its approach as a differentiator that results in more design flexibility, less bill-of-material costs and PCB space, and shorter time-to-market.

Other features of Z8 FMC16100 Series include:

  • Analog comparator

  • 5.53 MHz internal precision oscillator with a 2% accuracy variation

  • 16-bit timer

  • Single-pin, built-in debugger

  • Watch-dog timer (WDT), voltage brown out (VBO), power on reset (POR) 2.7-3.6 V operation

Besides silicon, firmware and development tools, as well as expert application support, complement Z8 Encore! MC family. It’s available in 32-pin, lead-free QFN (5 x 5 mm) or LQFP packages, via Zilog’s distributor network or online at www.zilog.com/z8encoremc. Pricing for the 16 KB version (standard temperature range) is $2.50, each, in 5,000 unit quantities.

Also available for the Z8 Encore! MC family is a comprehensive motor control-specific development tool suite, retailing at $199.95. It includes a bldc motor, application board, ZDS II with full ANSI C Compiler, motor control software code, and an opto-isolated USB smart cable for debugging/programming. A high-end, in-circuit emulator (ICE) kit, which includes package adapters and event-trace functions, retails for $1,999.

—Frank J. Bartos, executive editor, Control Engineering