Blood glucose monitors have been commonly used in Europe and the Americas for many years for the prevention and monitoring of diabetes. Due to changes in dietary habits this disease is now becoming more common throughout Asia, including Japan, leading to a growth in the demand for electronic glucose monitors. The requirement is to take measurements of blood sugar levels several times a day, so such products must be compact and have longer battery life to allow users to use them on the go. In addition, a side effect of diabetes is poor eyesight, so large LCD panels are usually required to display measurement results. An increasing requirement is to send information on the measured blood sugar levels to doctors in local hospitals, so a USB or Bluetooth interface provides the means to transfer the data to a recording PC.
In the measurement process, a very small current corresponding to the blood sugar level is output from a test strip. This is converted from current to voltage by an op-amp, and the resulting value is read by a high-precision A/D converter. Blood sugar level measurement requires an A/D converter with a resolution of 12 bits or more. Also, low power consumption is essential in order to achieve compactness and longer battery life.
The 78K0/LE3, LF3 and the H8/Super Low Power MCUs from Renesas Electronics have on-chip high-precision 14-bit A/D converters that are ideal for blood sugar level measurement. They also integrate the peripheral functions required for a blood glucose monitor, which helps to reduce overall cost and extend battery life.
System Block Diagram
|Block||Semiconductor Device||Recommended Products||Features, etc.|
|Main controller||MCU||78K0/LE3||On-chip LCD driver, 8-bit MCU|
|78K0/LF3||On-chip LCD driver, 8-bit MCU, high pin-count package|
|H8/38086R Group||On-chip LCD driver, low power consumption, on-chip 14-bit A/D|
|EEPROM||R1EX24xxx Series||I2C bus interface *1|
|Reset IC||RNA51Axx/Bxx Series||CMOS reset IC|
|General use |
circuit protection, etc.
|Zener diode||HZMxNB Series||3-terminal (1 device included) face-mount|
|HZU/HZC Series||2-terminal face-mount outline|
|NNCDxxDA Series||High ESD tolerance optimal for use in surge absorption|
|RDxxS Series||2-terminal face-mount outline|
|Switching diode||HSM2838C, HSM123||3-terminal (2 devices included) face-mount|
|HSU119/HSC119||2-terminal face-mount outline|
|Schottky diode||HRB0502A||3-terminal face-mount outline (low VF)|
|HRC0103C||2-terminal face-mount outline (low leak |
|HRV103A, RKR104BKH||2-terminal small face-mount outline |
(Io = 1 A)
|USB interface||Zener diode for surge |
|HZL6.2Z4, HZL6.8Z4||Low capacitance type, 1 device included|
|RKZ6.8Z4KT||Low capacitance type, 4 devices included|
*1 I2C: Inter-Integrated Circuit
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