RL78/L1A Group of Microcontrollers Integrate Precise Bio-Sensing Front Ends

SANTA CLARA, CA --- Renesas Electronics Corporation announce the RL78/L1A Group of low-power 16-bit microcontrollers (MCUs) with a liquid crystal display (LCD) driver that are ideal for battery-powered sensing devices used in healthcare applications such as blood glucose monitors, lactate analyzers, cholesterol analyzers, and other devices equipped with biochemical sensors. With the built-in analog front-end (AFE)1 circuit for biochemical sensing, the RL78/L1A enables blood glucose and hemoglobin measurements with only one monitoring device.

The RL78/L1A also delivers improved performance with high-precision analog functions as well as longer battery life. System designers therefore can leverage the low-power and improved precision analog 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 (RPBs), which allow system developers to immediately evaluate the RL78/L1A functions.

According to the World Health Organization (WHO)2 estimates, the number of adult diabetes patients worldwide in 2014 was 422 million. This corresponds to 8.5 percent of adults over 18 years of age and represents almost double the rate incidence from 1980 (4.7 percent). 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.

In addition, it has become an industry trend to implement multiple measurement features, such as blood glucose and hemoglobin 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. First, these new devices reduce power consumption, resulting in longer battery life. Second, the enhanced offerings integrate both analog 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:

In the healthcare field, when measuring a variety of vital signs, it is important to improve both the efficiency of analog functions and digital processing performance within the MCU itself.

(1) Integrated analog switches allow easy selection of the measurement target, increasing measurement flexibility

The RL78/L1A Group incorporates analog 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 hemoglobin and the blood glucose levels, could address these issues.

(2) Reference software contributes to improved precision analog

Renesas provides reference software that makes it easier to improve precision by using the internal AFE functions, such as 12-bit A/D converters, rail-to-rail operational amplifiers, internal reference voltages, and 12-bit D/A converters. In addition to improving device precision, this software can provide improved stability, contributing to improved precision analog functions in user systems.

(3) Lower voltage operation of the analog functions contributes to longer battery life in end products

Renesas has made various circuit improvements to the AFE, enabling a significantly 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 analog circuits could only operate down to 2.4 V3 and then stopped, these new products can be used fully down to 2.0 V.

Pricing and Availability

Samples of the RL78/L1A are now in six product versions, with 80- and 100-pin packages and with internal flash memory capacities ranging from 48 KB to 128 KB. Pricing varies depending on memory capacity, number of pins, and packaging. Mass production of the RL78/L1A has already begun. (Pricing and availability are subject to change without notice.)

In addition to releasing compact RPB products that allow designers to evaluate the functions of these new MCUs, Renesas plans to release reference software that is designed for use in blood glucose monitors as application notes and sample programs by the end of 2016.

For more information, visit http://www.renesas.com

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