An optical sensor for heart rate monitoring is optimized for wearable devices such as sports bands and smart watches. The BH1790GLC from ROHM Semiconductor uses proprietary analog circuit technology and optical sensor expertise to improve sensitivity, allowing pulse waves to be detected with high accuracy, even with low LED brightness, resulting in low power consumption.
A specialized optical filter enables high accuracy detection, extending battery life while reducing the effects of IR rays by 10x vs conventional products. This makes it possible to acquire high-quality pulse signals even in environments with strong IR presence, such as outdoors, or under intense movements (i.e. sports).
In addition, an optical heart rate monitor expansion board (BH1790GLC-EVK-001) for ROHM’s sensor shield can collect and process sensor information by connecting to an open platform (general MCU board) such as Arduino Uno.
The devices use a photodiode matched to the green wavelength for pulse detection, along with a filter structure optimized for pulse detection that integrates green and IR cut filters in the receiver block. Susceptibility to IR rays reduced by 10x compared with conventional products. The BH1790GLC is capable of detecting high-quality pulse signals using low VF low-brightness LED elements, eliminating the need for DC/DC circuits for LED power supply conventionally required. This decreases mounting area by 30%, lightening development load.
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