Renesas Electronics has introduced a new RL78/L1A series microcontroller with a precise biosensing front end built in for medical applications

Renesas Electronics announced the introduction of the RL78/L1A series of low-power 16-bit microcontrollers (MCUS) with liquid crystal display (LCD) drivers that are ideal for battery-operated sensors used in medical applications, such as blood glucose monitors, lactate analyzers, cholesterol analyzers and other devices equipped with biochemical sensors. The RL78/L1A has a built-in analog front-end (AFE, note 1) biosensing circuit that allows blood sugar and hemoglobin to be measured via a single monitoring device.

The RL78/L1A offers higher performance with high-precision simulation and longer battery life. As a result, system designers can take advantage of the RL78/L1A's low power consumption and higher precision simulation to create compact, lightweight medical devices with longer battery life, helping patients manage health issues such as diabetes more effectively. Renesas Electronics will also sell the Renesas Promotional Board(RPB), which enables system developers to immediately evaluate the functionality of the RL78/L1A.

According to the World Health Organization (WHO), the number of adults with diabetes worldwide reached 422 million in 2014. This equates to 8.5% of the adult population over the age of 18, almost double the figure in 1980 (4.7%). For people with diabetes, frequent and continuous monitoring of blood sugar is an important part of daily life in order to manage the condition and potential complications. To do this, portable blood glucose monitors are already widely used.

In addition, the implementation of multiple measurement functions, such as blood sugar and hemoglobin, through a single monitoring device has become an industry trend. However, these features require more complex system configurations, higher measurement accuracy, and longer battery life.

The new microcontroller developed by Renesas Electronics can improve the final product in two ways. First, reduce the power consumption of these new devices, thereby extending battery life. Second, analog and digital components previously provided as external components are integrated onto a single chip, thereby reducing the size of the board and reducing the cost of the final product.

Important features of RL78/L1A series microcontrollers:

In the medical field, it is important to improve the efficiency of analog functions and digital processing performance in microcontrollers when measuring various vital signs.

(1) The integrated analog switch allows easy selection of measurement targets, improving measurement flexibility

The RL78/L1A series utilizes analog switches not commonly used in microcontroller AFEs before. Combining the switch with the built-in digital-to-analog converter allows switching the measurement circuit (including external circuits in the software) when the target changes. For example, in devices such as blood sugar monitors, adjusting measurement accuracy based on differences in blood composition has become a problem. Flexible methods such as alternating measurements of hemoglobin and blood sugar levels can solve these problems.

(2) Reference software helps to improve simulation accuracy

The reference software provided by Renesas Electronics uses internal AFE functions such as 12-bit analog-to-digital converter, rail-to-rail operational amplifier, internal reference voltage and 12-bit analog-to-digital converter, making it easier to improve accuracy. In addition to improving device accuracy, the software also provides greater stability, helping to improve the accuracy of simulation functions in the user's system.

(3) The low voltage operation of the analog function helps to extend the battery life of the final product

Renesas Electronics has implemented various circuit improvements to the AFE, resulting in a significant reduction in the supply voltage. These improvements allow the measurement circuit that is the main function of the final product, such as a blood sugar monitor, to operate until the last moment of the system's effective battery life. Previous analog circuits operated at a minimum of 2.4V (Note 3), while these new products can operate at 2.0V.