Microcontroller aims at the heart of industrial inverter technology

The SH7137F delivers ample CPU performance with 100 DMIPS, which is perfectly supported by zero-wait MONOS (metal-oxide-nitride-oxide-silicon) embedded Flash. This generation of MONOS Flash has just 12.5ns read access time and hence supports 80MHz operation without tricks and is 100% deterministic. Furthermore the device has a fast and vectored interrupt response time, another important criteria for deeply embedded real-time systems. The SH-2 is a 32-bit RISC CPU core with 16 general purpose registers, each 32bit wide, and is ideal for coding in ‘C’. The SH-2 CPU also has a Multiply-Accumulate Unit (MAC) for DSP algorithms.

The MTU2 timer unit has 6 channels of 16 bit timers. Channels 3 and 4 can generate the 3-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 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 3, 4 and 5, so can generate a second set of 3-phase PWM to drive a second motor out of the SH7137F 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&H to measure the current in all 3 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 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.

The SH7137F line-up comprises of two 256Kbyte MONOS Flash versions, in 80pin and 100-pin QFP packages. An automotive version called SH7147F supports 125 degree C 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 256K, so that the SH7137F is supported for free. Beyond this, a free-yet-high-quality GNU C Compiler is available for download at www.gnush.com. A Renesas Starter Kit (RSK7137) is under development and scheduled to start shipping in March 2008. This Kit is complete (e.g. E10A included), user-friendly and low cost.