ISO 26262 compliant automotive MCUs for power steering and motor driving in electric cars

Toshiba Corporation is preparing to make available two automotive microcontrollers for electronic control units compliant with ISO 26262, a newly created functional safety standard for automotives. The new products are the "TMPM350FDTFG" for electric power steering control and the "TMPM354F10TFG" for control of drive motors of hybrid and electric vehicles. Toshiba to sample these microcontrollers in September 2011 and mass produce in April 2013.

The vehicle safety standard ISO 26262 for automotive electronic control units is expected to be published sometime in 2011. ISO 26262 is for implementing fail-safe functions in microcontroller chips, which are the principal components of electronic control units, to ensure safe control even in the event of failure of certain functions. The market for microcontrollers compliant with functional safety standards is expected to grow rapidly and is forecast to be worth approx. 1.26 billion US$ in fiscal 2015, estimated Toshiba.

Toshiba says its functional safety microcontrollers employ the "single-core tightly coupled method" whose CPU core has a dedicated monitoring circuit. Toshiba has licensed the tech from YOGITECH S.p.A. of Italy is applied to part of the monitoring circuit. Unlike the conventional "dual-core lock step method", the single-core tightly coupled method, with the built-in monitoring circuit, achieves immediate detection of internal system failure and can accurately narrow down the location of the failure, claims Toshiba. Toshiba suggests its microcontrollers are ideal for use in the development of fail-operational electronic control systems capable of maintaining operation of a vehicle with the minimum functions in the event of failure.

The TMPM350FDTFG with programmable motor driver, excitation signal output circuit for resolvers, AD converters, is suggested as ideal for applications like electric power steering, as more precise control is made possible through enhancement of the accuracy of external signal input from the motor and higher resolution of output signal.

The TMPM354F10TFG, used mainly for control of drive motors, incorporates an on-chip resolver to digital converter that converts signals from the motor resolver to digital data, resulting in a smaller footprint. Whereas conventional models applied only to rotation position sensors using excitation signals like resolver, the more versatile new product is also applicable to rotation position sensors that do not use excitation signals by correcting sensor input signals. Moreover, it reduces CPU operation cycles by more than 50% by having the hardware engine perform basic vector control operations of the motor, which were previously performed by software, as per Toshiba.

Outline of the new products

Part number Sample price (tax included) Sample shipment Mass production Production scale

TMPM350FDTFG 1,000 yen September 2011 April 2013 1 million units /year

TMPM354F10TFG 1,600 yen September 2011 April 2013 0.5 million units/year

Specifications

Part number TMPM350FDTFG TMPM354F10TFG

Core ARM Cortex -M3 core (32-bit)

Functional safety system Single-core tightly coupled system

Power supply voltage Dual power supply: I/O=5 V, Internal=1.5 V

Operating frequency 88 MHz 80 MHz

Built-in ROM/RAM Flash: 512 Kbytes
SRAM: 48 Kbytes Flash: 1 Mbyte
SRAM: 64 Kbytes

Built-in peripheral functions Programmable motor driver PMD: 1ch A-PMD: 1ch
Vector Engine

Timer 32-bit general-purpose timer: 7 units
32-bit general purpose timer with capture input: 1 unit 32-bit general-purpose timer: 5 units
32-bit general purpose timer with capture input: 1 unit

Resolver to
digital
converter None Δ∑AD converter + digital tracking circuit

12-bit AD converter 10 channels × 2 units 3 channels × 2 units
4 channels × 1 unit,
11 channels × 1 unit

CAN controller 2 channels 3 channels

CRC generator 1 channel 1 channel

Package LQP100
(14 mm × 14 mm, 0.5 mm pitch) LQFP144
(20 mm × 20 mm, 0.5 mm pitch)