Auto Electronics

Renesas MCU features MONOS embedded flash for electric motor control

A new 32-bit RISC microcontroller from Renesas Technology America Inc. is designed specifically for controlling electric motors in automotive chassis, safety and hybrid electric systems. The 64 MHz SH7147F, a member of the SuperH-family, is also the first such device to use Renesas’ metal oxide nitride oxide silicon (MONOS)) embedded flash technology.

The SH7147F uses the same 100-pin package as its predecessor, the 50 MHz SH7047F, but offers a 12-bit versus a 10-bit A/D converter, six channels capable of simultaneous sampling and conversion, versus two in the previous device, a 30% faster conversion time, and a twofold improvement in absolute precision. Applications for the chip include precision inverters for electrical power steering and dc to dc voltage conversion in hybrid electric and gas-powered cars and trucks.

The SH7147's 256 Kbyte on-chip flash memory is implemented by a 0.15 µ process, has a full-time single-cycle random access capability, and requires almost 60% less chip area than the same amount of flash built with floating-gate NOR flash technology. The MONOS cell design is also said to minimize losses, thus increasing reliability.

Shinichi Asano, marketing manager for Renesas’ automotive business unit, said the embedded memory technology offers advantages in speed and reliability. Peripherals include eight channels of 16-bit PWM timers and a 16-channel A/D converter with sample-and-hold circuits. The converter interacts with 16-bit PWM timers – the motor management timer and 32 MHz and 64 MHz multifunction timer pulse units – to implement precise inverter control.

Noting the trend toward networking in-vehicle systems, Asano said the SH7147F incorporates communication functions including a CAN interface, and a 4-wire synchronous serial communication unit (SSU) channel for selecting master or slave mode and performing synchronous serial communication even with devices that use a different clock polarity and different clock phase. The MCU also includes three on-chip serial communication interface (SCI) channels for asynchronous and synchronous serial communication, and it includes an 8-bit databus-width external expansion function and a data transfer controller (DTC) that allows data transfers to internal and external memory without CPU intervention. The SH7147F operates over the –40 °C to 125 °C temperature range.

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