Atmel has introduced two new 8-bit AVR microcontrollers for controlling sensor and sensorless brushless DC (BLDC) motors in automotive applications.
Michel Passemard, automotive tactical marketing director of Atmel's Microcontroller Business Unit, said that with an increasing number of motors inside a car, automotive manufacturers need smaller and lighter motors with higher torque than brush motors and are moving to BLDC motors that require more sophisticated electronic devices for precision control of speed and torque. Passemard said the trend brings new challenges, among them temperatures as high as 150 °C for some under-the-hood applications.
Atmel’s ATmega16M1 and ATmega32M1 were developed for high-temperature advanced motor control applications that also require CAN and LIN connectivity. Target applications include window lift motors with anti-pinch, braking assistance, steering wheel assistance, ventilation, cooling, sliding doors, and admission control and turbo charger control for which the motor and possibly its controller can be exposed to elevated temperatures beyond the standard 125°.
Based on the AVR 8-bit RISC architecture, the ATmega16M1 and ATmega32M1 integrate the basic peripherals needed for complex algorithms, according to Passemard. The devices integrate 10-bit A/D converters with differential amplifiers and programmable gain options, analog comparators with selectable comparison levels, and interrupt on pin change I/Os.
The MCUs also include independent positive and negative comparator inputs to allow sensorless motor control without the need for external active components. Three individual comparators are available for back electromagnetic field (EMF) measurements and an additional comparator is available for over-current detection. Its reference (comparison level) can be fixed via the D/A converter output or any external reference voltage.
A 12-bit synchronous power stage controller operating at up to 64 MHz generates six complementary programmable high speed and precision signals to control a motor's three half bridges. The resulting voltage resolution is approximately 1/1000. Hardware fault detection is designed to put the motor in a safe position immediately and automatically when a failure is detected.
Atmel’s new MCUs are supported by Vector CAN and LIN drivers as well as by Atmel's AVR Studio, AVR JTAGICE mkII, and the STK524 and STK600 with STK600-TQFP32 add-on starter kits. The AVRMC320 Motor Control evaluation kit is also available. Samples of the ATmega32M1 and ATmega32C1 are available, packaged in a 32-pin QFP/QFN. ATmega32C1, ATmega16M1 and ATmega32M1 will be qualified at 125 °C and 150 °C and available for volume production in August. Prices start at $2.34 in 10,000 quantities for the 125 °C version.