Other features include three 10-bit PWM complimentary output pairs complete with Dead Time function and full I/O polarity control. As Brushless DC Motor control operation requires the processing of feedback signals for protection against over-current and over-voltage situations, this new device includes integrated protection circuits along with an A/D converter, which are used together to ensure smooth rotational control as well as implementing the necessary protection features.

Regarding other features, the device has 4K x 16 of Flash Program Memory, 256 bytes of RAM Data Memory, 64 bytes of Data EEPROM, a 4.5~5.5V operating voltage range and an operating frequency of up to 20MHz. A fully integrated internal high accuracy RC oscillator is included along with an 8-channel high speed 10-bit analog to digital converter.

As for times, a 10-bit and a 16-bit timer is provided along with an additional 16-bit capture timer which are used to generate the 6-channel PWM control signals for motor speed control. These motor control PWM signals operate with a single period but have three fully independent duty adjustment controls. Both Low Voltage Detector and Low Voltage Reset functions are also included, which can be used to generate a warning signal or generate a reset when the power supply voltage falls below a fixed level.

These features combine to provide additional safeguards to ensure stable operation under low power supply voltage conditions. Three comparators are also included which can be used for the implementation of square wave sensor-less control. With regard to external interfacing and adding to the range of already comprehensive features, the device also includes I2C and UART interfaces.

The HT66FM5240 is available in both 20-pin and 28-pin SSOP package types and will see popular use in both single and three phase Brushless DC Motor Fan application area. As is the case with other Holtek 8-bit MCU devices, the HT66FM5240 meets with industrial specifications and has excellent noise immunity characteristics.