A range of low-power 16-bit microcontrollers (MCUs) has been announced by Renesas Electronics. The RL78/L1A Group microcontrollers have LCD drivers that are ideal for battery-powered sensing devices used in healthcare applications such as blood glucose monitors, lactate analysers, cholesterol analysers, and other devices equipped with biochemical sensors.
With the built-in analogue front-end circuit for biochemical sensing, the RL78/L1A enables blood glucose and haemoglobin measurements with only one monitoring device. The RL78/L1A also delivers improved performance with high precision analogue functions as well as longer battery life. System designers therefore can leverage the low-power and improved precision analogue of RL78/L1A MCUs to create compact and lighter medical devices with extended battery life, which can help patients manage health conditions, such as diabetes, more effectively. Renesas will also offer sales of Renesas Promotional Boards which allow system developers to immediately evaluate the RL78/L1A functions.
The World Health Organisation estimates the number of adult diabetes patients worldwide in 2014 was 422 million. This corresponds to 8.5% of adults over 18 years of age and represents almost double the rate incidence from 1980 (4.7%). For diabetes patients, frequent and consistent blood glucose monitoring is an important part of their daily routine to manage their condition and to control potential complications. To enable these, portable blood glucose monitors are already widely used.
According to Renesas: “it has become an industry trend to implement multiple measurement features such as blood glucose and haemoglobin measurements into one monitoring device. However, these features require more complicated system configurations and the burden of developing improved measurement precision and long battery been increasing.”
Renesas has developed new MCUs that contribute to end-product improvements in two ways. Firstly, these new devices reduce power consumption, resulting in longer battery life. Secondly, the enhanced offerings integrate both analogue and digital elements that were previously provided as external components onto a single chip, thus contributing to smaller circuit boards and reduced end-product costs.
Key features of the RL78/L1A Group of MCUs:
When measuring a variety of vital signs in the healthcare field it is important to improve both the efficiency of analogue functions and digital processing performance within the MCU itself.
Integrated analogue switches allow easy selection of the measurement target, increasing measurement flexibility
The RL78/L1A Group incorporates analogue switches that were previously uncommon in MCU AFEs. By combining switches with a built-in A/D converter, it is possible to switch the measurement circuit including external circuits in software when the target is changed. For example, in devices like blood glucose monitors, adjusting the measurement precision in response to differences in the blood components has become an issue. Flexible methods, such as alternating measurements between components such as haemoglobin and the blood glucose levels, could address these issues.
Reference software contributes to improved precision analogue
Renesas provides reference software that makes it easier to improve precision by using the internal AFE functions, such as 12b A/D converters, rail-to-rail operational amplifiers, internal reference voltages, and 12b D/A converters. In addition to improving device precision, this software can provide improved stability, contributing to improved precision analogue functions in user systems.
Lower voltage operation of the analogue functions contributes to longer battery life in end products
Renesas has made various circuit improvements to the AFE, enabling a lower supply voltage. These improvements allow the measurement circuit, which is the main function for end products such as blood glucose monitors, to operate down to the very end of the system’s effective battery life. While earlier analogue circuits could only operate down to 2.4V and then stopped, these new products can be used fully down to 2.0V.
The RL78/L1A is now available in six product versions, with 80- and 100-pin packages and with internal flash memory capacities ranging from 48 to 128KB.