Renesas' Microcontroller Feats MONOS Embedded Flash Technology

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Renesas Technology America has announced the SH7147F 32-bit RISC microcontroller specialized for controlling the electric motors increasingly being used in automotive chassis, safety and hybrid electric systems. The 64MHz, 32-bit SuperH-family device is the first MCU for automotive motor control systems to use Renesas' advanced MONOS (Metal Oxide Nitride Oxide Silicon) embedded flash technology that delivers speed, size, and reliability advantages.

The SH7147's MONOS-based 256Kbyte on-chip flash memory is implemented by a 0.15 micron process and has a full-time single-cycle random access capability. It requires almost 60-percent less chip area than the same amount of flash built with floating-gate NOR flash technology. Also, the MONOS embedded flash is more reliable because its cell design minimizes losses.

The set of peripherals built into the SH7147 MCU for automotive applications include eight channels of 16-bit PWM timers and a 16-channel analog-to-digital (A/D) converter with sample-and-hold (S/H) circuits. These and other on-chip functions, combined with the MCU's high computing performance, allow cost-effective precision inverter designs for electrical power-steering and various DC-to-DC voltage conversion applications in hybrid electric and gas powered cars and trucks.

The 64MHz SH7147F is a second-generation product that provides functional and performance improvements over the 50MHz SH7047F, while using the same small 100-pin package. Besides having a 28-percent faster CPU speed, the SH7147F has a more sophisticated data converter. The enhanced A/D offers higher resolution (12 bits, up from 10), additional channels capable of simultaneous sampling and conversion (six, up from two), and a quicker conversion time (about 30 percent faster). Also, it achieves approximately a two-fold improvement in absolute precision, for more accurate inverter control.

The A/D converter interacts with the on-chip 16-bit PWM timers to implement precise inverter control. Those timers comprise the MMT (Motor Management Timer) and MTU (Multifunction Timer pulse Unit). The latter consists of the MTU2 and MTU2S, which have higher operating speeds: 32 and 64MHz, respectively. The timers are easier to use, too, thanks to new features such as an A/D conversion start-request delayed function and an interrupt-request thinning-out function.

In modern automobiles, the trend is for more of the in-vehicle systems to be networked together. As a result, the new MCU incorporates comprehensive communication functions for easy connections to other electronic units, subsystems and ICs. A CAN (Controller Area Network) interface is compatible with the CAN in-vehicle LAN specification. A 4-wire SSU (Synchronous Serial communication Unit) channel allows the selection of master mode or slave mode and can perform synchronous serial communication even with a device that uses a different clock polarity and different clock phase. Three on-chip SCI (Serial Communication Interface) channels can handle both asynchronous and synchronous serial communication. Additionally, the MCU has an 8-bit data-bus-width external expansion function and a DTC (Data Transfer Controller) that allows data transfers to internal and external memory without CPU intervention.

The SH7147F operates over a wide ambient temperature range (–40°C to +125°C), so it can be used in difficult environments — the engine compartment of a vehicle, for example. It is packaged the same compact 100-pin LQFP (14 mm x 14 mm, 0.5 mm pin pitch) as the SH7047F device, allowing upgrades with existing circuit boards. Also, the SH7147F maintains software compatibility that the SH7047F, so the newer device can run application code written for its predecessor, saving development time. Available system development tools include an integrated development environment with C/C++ compiler package, simulator/debugger, project management tools, and a flash memory programming tool, as well as an emulator (the E200F).

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