8-bit Brushless DC Motor Controller MCU – HT45RM03

01/19/2007

With a focus on the area of three phase Brushless DC Motor control, Holtek Semiconductor announces the release of its new 8-bit microcontroller, the HT45RM03. Device features include 4K of OTP Program Memory, 192 bytes of Data Memory, a working voltage range of 2.2V~5.5V and an operating frequency of up to 12MHz as well as 23 I/O pins, with wake-up functions. The internal A/D converter has 8-channels and a resolution of 9-bits. The internal Programmable Frequency Divider can generate fixed frequencies on an output pin, which can directly drive audio components such as buzzers etc. These functions are complemented by two internal 8-bit timers and an internal Low Voltage Reset function which can generate a reset should the power supply voltage fall below the minimum level for proper system operation thus eliminating unstable operation due to low power supply voltage conditions.
With specific regard to Brushless DC Motor control, the device provides some specific functions. One of these is the provision of four external interrupt pins, of which three are used to sense the transmitted rotational signals from external Hall Effect Sensors. By using external interrupt methods, software overheads to sense rotational information signals can be greatly reduced. Other features are the three 10-bit PWM high frequency carrier wave outputs which are used to control the three phase Brushless DC Motor rotational speed. Each PWM output also has its own complementary output which can implement a motor synchronous rectification function. To ensure correct operation of the Brushless DC Motor control, it is necessary to have some feedback signal which can sense and protect against situations of over-current and over-voltage. In this regard the HT45RM03 has a fully integrated operational amplifier and a comparator which can be used to amplify the DC motor current detect signal. The combination of the operational amplifier, comparator and A/D converter, can be used together to ensure smooth rotational control as well as implementing protection functions.
The HT45RM03 when used in combination with the recently developed HT45B0C High Voltage MOSFET Driver device, provides designers with a complete and convenient solution for applications involving Brushless DC motor control. Taking into account device functional characteristics or cost considerations, this choice of components is certain to provide users with an excellent device solution. Application areas could include electric bicycles, vacuum cleaners, motorised exercise equipment and in fact most applications whose products require the use of a Brushless DC motor.
The HT45RM03 meets the requirements of industry specifications. At present the ICE Development Tools and Demo Board for electric bicycle applications are available. The HT45RM03 device is available in a choice of 28-pin SKDIP and 28-pin SOP package types, while the HT45B0C is available in both 24-pin SKDIP and 24-pin SOP package types. As both devices have already entered production, samples are available for customer assessment and production orders can be accepted.