Electronic fuel injection reference design for small engines

With increasingly tight global pollution standards for even small engines, STMicroelectronics and Arrow Electronics have produced am electronic control unit (ECU) reference design for single and twin-cylinder fuel-injected petrol engines.

Called SPC5-L9177A-K02, the ECU reference design is aimed at motorcycles, scooters, and three wheelers – particularly those which must satisfy Euro 5, Bharat Stage VI (BSVI), and China IV standards. ST also foresees use in generators, nautical engines and agricultural equipment.

It can driver injectors, a relay, a stepper motor and tachometer, and interface with variable reluctance sensors – all channels are protected against short circuit and over-temperature condition. Connection is through an automotive 48-pole connector.

Key components are ST’s SPC572L 32bit Power Architecture MCU and its L9177A – the latter is made on a BCD process and includes power supplies and actuator drivers for engines with one or two cylinders – a 300mA 5V regulator with thermal shut-down, a 5V tracking regulator with short-to-battery protection, two fuel injector drivers, a driver for the engine idle speed control stepper motor, an oxygen-sensor heater output, and diagnostic features.

Both SPC572L and L9177A “are specifically designed for the application and market needs”, said ST, whose STGD18N40 IGBT and L9616 CAN interface IC also feature on the board.

Also available on the SPC572L MCU are timers, 16 input channels, 56 output channels, 1.5Mbyte read-while write (RWW) flash (with EEPROM emulation), 64kbyte general-purpose data SRAM, two deserial/serial peripheral interface (DSPI) modules, an analogue-to-digital converter and self-test capability.

Support comes from SPC5Studio IDE (integrated development environment) which includes low-level drivers, an SPC572L timer module configurator and libraries for engine crank position sensing and associated actuators.

“To overcome the complex challenges associated with electronic fuel injection, a basic application software developed in association with eMoticom helps users start and manage a single-cylinder engine,” said ST. This appears to for a single-cylinder 250cc 4-stroke with one injector, and includes air temperature, water temperature and barometric pressure compensation.

SPC5-L9177A-K02, which measures 100 x 70mm, can be bought from Arrow.