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Analog ICs gear up for automotive engine control

Posted: 29 Jun 2007 ?? ?Print Version ?Bookmark and Share

Keywords:automotive MCUs? automotive engine management? H-bridge power ICs? output drivers?

Freescale Semiconductor is introducing six standard SMARTMOS analog products designed for automotive engine management applications to meet the industry's performance, fuel efficiency and environmental requirements. This expanded SMARTMOS line-up includes signal conditioning, H-bridge and output driver components for the company's automotive MCUs.

Aimed at managing specialized engine control functions while operating in harsh automotive environments, Freescale's portfolio of analog products for high-current powertrain applications includes output drivers, signal monitoring and conditioning devices and H-bridges. These products can be mixed and matched with Freescale's complementary MPC55xx 32bit MCUs, which support a variety of multi-cylinder engine control applications. Built on Power Architecture technology, the MPC55xx MCUs are fully synthesizable SoC devices optimized for automotive applications including powertrain control.

Output drivers
The new output drivers include the MC33800 and MC33810 devices. MC33800 is a 16-channel, multi-function output driver featuring eight low-side drivers, six FET pre-drivers and two constant current low-side drivers. MC33800 is designed to control relays, motors, solenoids, lamps, valves and heated exhaust gas oxygen (HEGO) sensors. Applications include engine and transmission control, electronic power steering, four-wheel drive control and industrial and commercial control systems that require low-side drivers with diagnostic reporting and fault protection.

The MC33810 low-side driver provides a programmable interface between the engine control MCU and the spark ignition and fuel injection functions of a gasoline engine. Applications include automobiles, motorcycles, industrial engines, generators, marine craft and other recreational vehicles. MC33810 is said to be one of the first flexible engine control interface circuits that scales easily for various engine cylinders. The device integrates four low-side drivers and four PWM-capable pre-drivers that can be configured to drive fuel injectors, solenoids, external FETs or IGBTs. The MC33810 is said to significantly reduce the number of components in an engine control unit, reducing its size, cost and complexity.

Signal monitoring ICs
The signal monitoring and conditioning devices include the MC33811 and the MC33975. MC33811 is a five-channel solenoid monitoring device used to determine the correct operation of a solenoid. The device determines whether there is a problem with a solenoid opening and closing by monitoring the profile of the solenoid's current waveform. Applications include automatic transmissions, fuel injectors and other control valve actuators.

MC33975 is an enhanced interface IC designed to detect the state of 22 switch inputs: 14 switch inputs to ground and 8 switch inputs for contacts to ground or to battery. All 22 inputs can be configured as analog signal inputs multiplexed and buffered for use by off-chip circuitry. A member of Freescale's Multiple Switch Detection Interface family, MC33975 can connect to any SPI-enabled MCU, providing a protected switch-level interface and an analog input signal capability. The device has been enhanced to provide 32mA of current per output to switched 5V sensors, as well as input sensing. MC33975 also can be used in automotive body control modules and in industrial and commercial control systems.

H-bridge power ICs
The MC33899 and MC33926 devices are monolithic H-bridge power ICs designed for electronic throttle control and low-voltage DC servo motor control applications. The devices can drive DC motors or bidirectional solenoid-controlled actuators, such as throttle control or exhaust gas recirculation actuators. They can also be used in harsh powertrain environments.

MC33899 features an SPI interface to the system MCU to enable advanced diagnostics, programmable current limit and a selectable slew rate. It also offers a higher output current than the MC33926. A fault restart feature allows the MC33899 to be configured to regulate high load currents below the programmed current limit.

MC33926 offers a simple input control to enable precise load management without an SPI interface. The device's feature set is a subset of the broad programmability of the MC33899. MC33926 also has a smaller footprint package than MC33899. This thermally enhanced compact PQFN package makes MC33926 a suitable solution for small-footprint engine controllers.

A demonstration of an engine control solution based on some of the Freescale analog devices has been on display at the Freescale Technology Forum (FTF) Tech Lab in Florida, U.S. this week.

Samples of the analog SMARTMOS devices for engine control are now available. These devices are supported by evaluation boards and a USB to SPI interface board. KITUSBSPIEVME board enables a PC without a parallel port to communicate with other Freescale evaluation boards via a USB port. Suggested resale pricing for the KITUSBSPIEVME is $65.

For the analog products, suggested per-unit resale pricing of the MC33800 16-channel output driver is $2.40, the MC33810 eight channel ignition and injector driver is priced at $2.28 and the MC33811 five-channel solenoid monitor sells at $1.20, all in quantities of 10,000.The MC33899 programmable H-bridge motor driver sells at $3.29 each, the MC33926 throttle control H-bridge costs $2.03 each and the MC33975 22-channel multiple switch detection interface is priced at $1.91, in 10,000-piece quantities.

- Gina Roos

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