MNOS-based MCU targets electric motors in vehicles - Embedded.com

MNOS-based MCU targets electric motors in vehicles

Taking advantage of its nonvolatile Metal Oxide Nitride Oxide technology, Renesas has just introduced a new 32 bit RISC microcontroller specifically designed for controlling the electric motors being used in automotive chassis, safety and hybrid electric vehicle systems.

According to Shinichi Asano, marketing manager, automotive business unit at Renesas Technology America, Inc., the 64MHz, 32-bit SuperH-based SH7147F is the first MCU for automotive motor control systems to use Renesas' advanced MONOS (Metal Oxide Nitride Oxide Silicon) embedded flash technology.

He said that 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 sameamount of flash built with floating-gate NOR flash technology.

Beyond the MNOS, what sets the SH7147F apart is the array of peripheral functions added specific to motor control in automotive applications. The device includes eight channels of 16-bit PWM timers and a 16-channel analog-to-digital (A/D) converter with sample-and-hold (S/H) circuits, necessary in the precisioninverter designs for electrical power-steering and various DC-to-DC voltage conversion applications in hybrid electric and gas powered cars and trucks.

An enhanced on-board 12- bit analog to digital converter is capable of simultaneous sampling and conversion (six, up from two), and a quicker conversion time.

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 and incorporate functions that make them easier to use, such as an A/D conversion start-request delayed function and aninterrupt- request thinning-out function.

Because the trend is for more of the in-vehicle systems to be networked together, Asano said 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 CANin-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.

He said the SH7147F operates over a wide ambient temperature range (“40C to +125C), 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 earlier 50 MHz SH7047F device, allowing upgrades with existing circuit boards. Also, the SH7147F maintains software compatibility that theSH7047F, so the newer device can run application code written for its predecessor, saving development time.

Development tools include an integrated development environment with C/C++ compiler package, simulator/debugger, project management tools, and aflash memory programming tool, as well as an emulator (the E200F).

Available now in sample quantities the SH7147F (R5F71474) with 256Kbytes of MNOS and 12k bytes of RAM in a 100-pin is $25.75 each.

Renesas Technology
San Jose, Ca.
408-382-7501
www.renesas.com

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