MCUs take control of automotive motors

Microcontroller line is ideal for the next generation of industrial inverters, in particular where the drive is built into the motor, as well as many automotive applications.

Renesas Technology Europe has introduced the SH7147F microcontroller lineup that is ideal for the next generation of industrial inverters, in particular where the drive is built into the motor, as well as many automotive applications such as electronic power steering (EPS).

The device integrates 256Kbyte super-fast MONOS Flash that supports fully deterministic 80MHz zero-wait operation yielding over 100DMIPS CPU performance.

It has two powerful timer units (MTU2, MTU2S), each capable of driving a motor, and two 12bit fast ADCs for measuring the phase currents and thus provides for three sample and hold (S and H) circuits in each ADC.

The conversion time is as fast as 1.25us.

For integration of the drive into the motor, Renesas developed a wide-temperature-range version up to 125C.

As with all members of the SH2 family of microcontrollers, the SH7147F delivers ample CPU performance of 100MIPS, which is perfectly supported by zero-wait MONOS (metal-oxide-nitride-oxide-silicon) embedded Flash.

This generation MONOS Flash has just 12.5ns read access time and hence supports 80MHz operation without tricks and 100% deterministic.

Furthermore the device has a fast and vectored interrupt response time, another important criteria for deeply embedded real-time systems.

The SH2 CPU is a 32bit RISC machine with 16 general purpose registers, each 32bit wide, and is ideal for coding in C.

The SH2 CPU also has a multiply-accumulate unit (MAC) for DSP algorithms.

The SH7147F lineup starts with a 256Kbyte MONOS Flash version, that has a single CAN channel.

Versions with up to 512Kbyte MONOS Flash and two CAN channels are under development.

The MTU2 timer unit has six channels of 16bit timers.

Channels three and four can generate the three-phase PWM as needed for electrical motors.

Channel 2 understands quadrature encoder feedback often used in high-performance inverters.

The MTU2 also supports immediate hardware emergency-shutdown and 15mA sink currents for direct optocoupler drive.

The MTU2 uses channel five as a dedicated dead-time control aid, so that dead times can be precisely set to achieve both, prevention of dangerously high cross-currents across the power bridges and prevention of conservative dead times, which reduces efficiency.

The MTU2 also has two channels for general purpose timer tasks.

MTU2S is a copy of channels three, four and five, so can generate a second set of three-phase PWM to drive a second motor out of the SH7147F microcontroller.

The two ADC have been designed to meet the requirements of such high-performance inverters.

Each one has 12bit resolution, a very fast 1.25us conversion time and three S and H to measure the current in all three phases simultaneously.

The peripheral set also features three serial ports (SCI), one synchronous serial communications unit (SSU, SPI-compatible), the popular data transfer controller (DTC) to offload the CPU from data movements, a watchdog timer (WDT), a compare-match-timer (CMT) and up to 57 IO ports.

A bus state controller (BSC) allows for an 8bit external bus for the connection to external peripherals such as USB or Ethernet NICs.

Finally the device has 16Kbyte RAM.

Samples of the SH7147F are available now in RoHS-compliant 14 x 14mm 100-pin QFP packages.

The device is supported by Renesas' high-end E200F emulator and the High-Performance Embedded Workshop (HEW) toolchain including C compiler, linker, editor, debugger and Renesas Flash Development Tool kit (FDT).

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