8bit microcontrollers equipped with high-accuracy oscillator circuit

Paul Boughton

LAPIS Semiconductor Co Ltd has developed 8-bit microcontrollers equipped with an oscillator circuit that provides more than twice the accuracy compared with previous models.

The ML610Q101 and ML610Q102 utilise motor control technology optimised for controlling rotation in single-phase fan motors.

In addition, the industry-leading high-accuracy oscillator circuit reduces rotational variations, while multiple timers minimise noise. A hysteresis differential comparator is also built in that allows a Hall element to be used, contributing to lower costs.

Additional features include a compact 16pin package 4mm X 4mm, ensuring compatibility with small fans, and high noise immunity (cleared the ±30kV level in IEC61000-4-2 noise testing), making them ideal for applications with demanding noise requirements, such as industrial equipment.

In recent years, as electronic equipment becomes more compact, devices such as PCs and servers require smaller cooling fan motors. CPU servers that process large amounts of data often utilize multiple cooling fans, and if there are variations in the rotation of each fan a buzzing sound can be generated due to differences in the wind noise frequencies. Also, if the change in current during ON/OFF switching in the motor coil current control is too large, irritating electromagnetic noise can result. Overcoming these obstacles requires smaller microcontrollers with high accuracy rotational control.

In response, LAPIS Semiconductor has developed an integrated oscillator circuit and a regulator for logic power supply that does not require external capacitance, providing a two-fold improvement in oscillator accuracy compared with conventional models – the highest in the industry. This minimizes rotational variations with single-phase fan motor rotation control, while numerous timers provide quiet, high efficiency performance through soft switching operation. As a result, the number of parts required can be reduced, since there is no need to add an external oscillator or capacitors for the logic power supply regulator. Plus, the compact package enables smaller mounting boards to be used.

Carefully designed circuit and layout have enabled high noise immunity, making it possible to clear the ±30kV level, which exceeds the measurement limit of Class 4 (±15kV), the highest class defined by the IEC61000-4-2 standard established by the IEC (International Electrotechnical Commission). This makes the LSIs suitable for use in industrial equipment with stringent noise requirements.

A complete support system is provided, including an ML610Q102 reference board and software development environment that make it easy to begin evaluation of the ML610Q101 and ML610Q102.

For more information, visit www.lapis-semi.com