​LAPIS Semiconductor’s Low Power Consumption Microcontroller Technology and Product Trends

1. Expectations for Microcontrollers

Currently, approximately 8.6 billion microcontrollers, which are considered the heart of electronic devices, are used annually throughout the world. (See Fig 1) And although the need continues to grow for different types of Microcontrollers to suit a variety of markets and applications, what is most commonly required is low-power consumption.

Fig 1. Worldwide Microcontroller Sales Volume (2013 Survey by WSTS Corp.)

Extremely low power consumption is required to increase the operating time in battery-driven devices (i.e. clocks, alarms, power tools) for even just a little while longer. Recent attempts have also been made to reduce power consumption in Microcontrollers for industrial equipment that operate continuously in an effort to minimize power consumption for entire plants. Consequently, low power consumption is desired in virtually every market and application, but at the same time improved performance is also demanded. For this reason there is an increasing need for high efficiency microcontrollers that improve system performance while reducing power consumption within the Microcontroller itself.

In response, LAPIS Semiconductor, a ROHM Group Company, has developed microcontrollers that provide both industry-low power consumption along with high efficiency processing, making them ideal for industrial equipment (i.e. motors) as well as general consumer electronics such as home appliances, wearable devices and so on. Below are 3 Microcontroller solutions that meet these needs.

2. Original 16bit Core Improves Performance while Reducing Power Consumption

LAPIS Semiconductor is expanding its lineup of Microcontrollers that utilize its original CPU core. Among these is the ML620Q504, which integrates its proprietary 16bit CPU to achieve greater processing performance with low power consumption (Fig 2). This effectively doubles the CPU bus width based on the ML610Q400 series (8bit original CPU core) designed for battery-driven devices such as clocks and calculators, quadruples the frequency (from 4MHz to 16MHz), and improves processing performance by 8 times – all while maintaining low power consumption (Fig 3).

Fig 2. LAPIS Semiconductor Microcontroller Map

Fig 3. New CPU Core Improves Performance

Generally, there are two cases in which the Microcontroller functions. One is where the Microcontroller is in continuous operation from the moment the power is turned on, and the other is where the Microcontroller is powered but in standby mode and goes into operation only when needed. In the case where the Microcontroller is constantly operating the required power consumption is referred to as operating current and expressed in W/MHz. Generally, as the frequency increases higher processing capability becomes possible, but this results in increased current consumption. In response, LAPIS Semiconductor’s CPU utilizes a 3-stage pipeline architecture (Fetch/Decode/Execute) to efficiently process 1 instruction per clock cycle, improving performance and processing capability without sacrificing power consumption. In addition, integrating a coprocessor that enables hardware-based calculations not only makes control possible (as a controller), but achieves low power consumption as well, even in applications that require processing operations (calculations). There is also a method for lowering the overall power consumption by controlling the operating and standby modes, but in such a case the key lies in how best to combine the different modes built into Microcontroller (generally referred to as Stop and Halt modes). However, LAPIS Semiconductor Microcontrollers include multiple Halt modes that can be precisely controlled to reduce power consumption even further. (Fig 4)

Fig 4. Reducing Average Consumption Current By Combining Power-Down Modes

3. TOUGH Microcontrollers with High Noise Immunity

In recent years, new requirements are emerging for Microcontrollers. Among them is increased noise immunity. The effects of noise cannot be ignored, even in industrial equipment or general home appliances. Many familiar sources of noise exist, including motors in washing machines and vacuum cleaners, compressors in refrigerators, heaters in IH appliances, and magnetrons in electronic ranges. And although these noises have no effect on human beings, they can cause malfunction in sensitive electronic components such as Microcontrollers, making it necessary to provide adequate protection. Generally, shielded wires are used on the PCB to protect against noise, and diodes and other components are integrated in electronic equipment to prevent noise from escaping.

However, due to shortened development cycles caused by intensifying competition, development has focused on other areas besides noise countermeasures, such as adding new functionality. And in many cases previous noise countermeasures have been adopted that prevent cost reductions at the board level, including reducing PCB area and/or the number of external components.

LAPIS’s Tough Microcontroller series (ML610Q100 and ML620Q100) take advantage of these breakthroughs in board design, such as adopting a structure to guard against abrupt changes in electric potential and implementing countermeasures for signal noise or noise introduced from the power supply line (Fig 5). The potential of VDD and GND continuously changes minutely in response to various factors, but when affected by noise the fluctuation can be dramatic, with a peak exceeding the Microcontroller’s maximum voltage tolerance. To combat this, LAPIS’s Tough Microcontrollers integrate a capacitor that reduces the peak voltage by suppressing these sudden fluctuations. In addition, to guard against sudden variations in signal lines caused by the same phenomenon, a filter is built in that cuts the peak voltage in order to prevent abnormal signals from propagating to the IC. As a result, the ICs were able to clear the measurement limit of ±30 kV, which exceeds the highest level (Class 4: ±8kV) during IEC61000-4-2 noise testing (Table 1).

Fig 5. Double Countermeasures for Power-supply and Signals

Table 1. ESD Noise Immunity Evaluation Results (LAPIS Comparison)

4. Proposed Systems: Smartphones to Wearables and Sensor Nodes

Since the development and mass production of a sensor control Microcontroller in 2012, LAPIS Semiconductor has been supplying not only individual Microcontrollers, but a development environment that combines sensors into total solutions. The ML610Q790 and ML630Q790 series released as sensor control Microcontrollers include a sensor hub feature for smartphones (Fig 6). Only sensor measurement values and algorithm calculation results are transmitted to the host processor, reducing operating load and contributing to lower power consumption of the entire system. In addition, the Microcontrollers are equipped with a task control mechanism for control of various sensors that make sensor driving and algorithm processing more efficient, leading to decreased weight and lower power consumption. Implementing these hardware- and software-based solutions makes it possible to obtain sensor measurement values at optimum intervals. This enables calculation of calibration and sensor fusion (rotation vector calculation), activity recognition (trains, buses, automobiles, bicycles, walking, running), and health & fitness functions (pedometers, activity meters, etc.).

Fig 6. Hardware and Software Solutions Using a Sensor Control Microcontroller

Hardware solutions that combine Microcontrollers and sensors, along with software solutions that include driver software and algorithms, can be applied to smartphones and other applications utilizing sensors (Fig 7). For example, integrating a sensor control Microcontroller in wearable devices in consumer applications makes it possible to transmit only pedometer results, calories burned, or other parameter, reducing communication frequency and shortening communication time and thereby contributing to lower power consumption.

Fig 7. Sensor Control Microcontroller Application Example

5. Development Environment

Most LAPIS Semiconductor Microcontrollers utilize a proprietary CPU core. Integrated development environment software is provided that includes a C compiler, project management, build, debugging, and flash programming tools, as well as hardware such as an on-chip debugging emulator and reference board, making it easy to start development at any time.

Fig 8. Comprehensive Development Environment

6. Future Initiatives

LAPIS Semiconductor will continue to offer Microcontrollers for industrial equipment and consumer applications utilizing market-leading low power technology, along with developing and providing design references and optimized solutions customized to user needs.