Freescale Semiconductor's MC33812 ignition and injector driver is an analog power IC design to control small one- and two-cylinder engines and the inordinate amount of pollution they cause compared to their larger automotive engine cousins.

Small engines are not only found on lawn mowers and weed whackers but extensively in the developing world on scooters and other vehicles. Freescale claims a typical three-wheel, carbureted two-stroke taxi found in Asia produces 50 times the emissions of a modern car.

Around the world there are many more small internal combustion engines for vehicles and other machines such as lawn mowers etc. than what we usually think of for car and truck power. And since most to these run on carburetors rather than modern electronic fuel injection (except for NASCAR dinosaurs), they pollute more.

The Freescale driver, combined with a 16-bit S12 MCU into the MCZ33812 integrated circuit reference design controller circuit (shown below), allows equipment and vehicle makers to incorporate precise fuel-injection or electronic-carburetion control on smaller engines—cutting pollution 35-65%, depending on specific emission constituent. Based on the company's more sophisticated microelectronic processors that usually cost more than small equipment makers can afford, the new chip uses the same IP but in a low-cost package that only has more bare-bones MCU processing power needed for simpler engine control. The result is lower emissions and system complexity (less integrated designs would need four ICs)—along with compact size, and reduced materials and manufacturing costs—but with a boost in horsepower.

The MCZ33812 combines a voltage regulator, fuel injector driver and ignition pre-driver, as well as a relay and lamp driver, watchdog timer and reset generator, all optimized for closed-loop small engine control (see diagram above). Previous small displacement engines are open-loop mechanical systems.

The reference design is a working control unit. It is loaded with engine control software (for a Yamaha C3 scooter) that can be modified. A CAN interface in the MCU even allows users to develop calibration tables (engine maps).

To help potential customers ramp up into electronic control, Freescale has a small engine control IC evaluation board available (see below).

"The board comes with a GUI that runs on a PC via USB, so users can command and "probe" registers without having to write code," says Ralph Ferrara, Freescale product definition engineer. They can then connect to loads to observe how the controls work. "If they have an existing application, they can wire via USB to the existing circuit to drive the board," he adds.

The consumer level MCZ33812 is available now for $1.70 in quantities of 10,000. The MCZ33812A, with automotive-grade testing and quality, should be shipping in Q4 2009. For spec sheets, click the links in the text above.