Chip has all analogue for engine management
For small petrol engines, Freescale has introduced an analogue mop-up chip to fire the ignition, pump the fuel injection, and read sensors in engine management systems.
“Small engine makers are increasingly deploying electronic engine controls, including EFI or e-Carb and electronic ignition for motor bikes, motor scooters and power equipment,” said Gavin Woods, v-p of Freescale’s analogue division. “Current solutions rely mainly on discrete components. This device integrates the requirements of tier-one ECU [engine control unit] developers who supply motorcycle and scooter manufacturers.”
There are two chips, both designed to work with a microcontroller to handle the digital side:
“The ICs compliment and extend Freescale’s motorcycle ECU reference platform, which retains the MC9S12 microcontroller but benefits from further integration and improved diagnostic capabilities,” said Freescale.
MC33813 is for one-cylinder engines, and has five low-side drivers and two pre-drivers.
MC33814 is for one-cylinder engines, and has six low-side drivers and three pre-drivers.
Both include a variable reluctance sensor (VRS) input circuit, a voltage pre-regulator (external pass transistor) and two 5V regulators – one to feed the MCU and the other as a protected sensor supply.
Also included is reset circuit and watchdog for the microcontroller, an ISO 9141 K Line interface for diagnostic communication, and a serial (SPI) interface.
The low-side drivers can drive up to two fuel injectors, a lamp, two relays or other loads, such as a fuel pump and a tachometer.
The pre-drivers can drive IGBTs or mosfets to control ignition coils and a heater for a HEGO (heated exhaust gas oxygen sensor).
The devices are packaged in a 48-pin LQFP with an exposed pad.
On the software side: low-level drivers will be provided for the MC9S12 MCU family “to take advantage of the improved diagnostic reporting via SPI”, said Freescale.
There is code to track crank position, read analogue sensors, determine fuel quantity and ignition timing, and schedule ignition coils and fuel injectors.
“The pin compatible S12EXP calibration device will be retained and a new cost effective calibration solution using the K-line diagnostics port is in development,” claimed the firm.
Application are also expected in three-wheeled taxis, lawnmowers, garden tractors, trimmers, edgers, chain saws, generators and outboard motors.
MC33813 and 33814 are included in the firm’s product longevity program, with a minimum of 15 years of product availability.