Microcontrollers suit new industrial inverters

The SH7137F delivers ample CPU performance with 100 DMIPS, which is supported by zero-wait MONOS (metal-oxide-nitride-oxide-silicon) embedded Flash.

Renesas Technology Europe has introduced the SH7137F microcontroller line-up, which is suitable for the next generation of industrial inverters (motor control), in particular for mainstream drives from 1 to 100kW.

The device integrates 256Kbyte Monos Flash, which supports fully deterministic 80MHz zero-wait operation, yielding over 100 Dhrystone MIPS CPU performance.

It has two timer units (MTU2, MTU2S), each capable of driving a motor and two 12bit fast ADCs for measuring the phase currents.

The system provides for three sample and hold (SandH) circuits in each ADC.

The conversion time is as fast as 1.25us.

The SH7137F delivers ample CPU performance with 100 DMIPS, which is supported by zero-wait MONOS (metal-oxide-nitride-oxide-silicon) embedded Flash.

This generation of Monos Flash has a 12.5ns read access time and hence supports 80MHz operation and is 100% deterministic.

The device has a short and vectored interrupt response time, another important criteria for deeply embedded real-time systems.

The SH-2 is a 32bit RISC CPU core with 16 general purpose registers, each 32bit wide.

It is suitable for coding in OC.

The SH-2 CPU also has a multiply-accumulate unit (MAC) for DSP algorithms.

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

Channels 3 and 4 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 opto-coupler drive.

The MTU2 uses channel 5 as a dedicated dead-time control aid, so that dead times can be precisely set to prevent dangerously high cross-currents across the power bridges, without requiring conservative dead times, which reduce efficiency.

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

MTU2S is a copy of channels 3, 4 and 5, so the system can generate a second set of three-phase PWM to drive a second motor out of the SH7137F microcontroller.

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

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

The peripheral set also features three serial ports (SCI), one synchronous serial communications unit (SSU), one IIC channel, 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 I/O ports.

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

The device has 16Kbyte RAM.

The SH7137F line-up comprises of two 256Kbyte MONOS Flash versions, in 80 and 100-pin QFP packages.

The SH7147F automotive version supports a 125C temperature range, for drives that are built near to or even into the motor.

Samples of the SH7137F are available now in a RoHS-compliant 14x14mm 100-pin QFP package.

The SH7136F uses a 80-pin package.

The device is supported by Renesas' E10A-debugger (JTAG) and the high-performance embedded workshop (HEW) tool chain including C compiler, linker, editor, debugger and Renesas flash development tool kit (FDT).

The demo version of the Renesas C Compiler has a code-size limit of 256Kbyte, so that the SH7137F is supported for free.

A free GNU C Compiler is also available.

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