Maxim Integrated's MAXREFDES117# reference design is a low-power, photoplethysmographic (PPG) based heart-rate and pulse oximetry monitor subsystem. The circuit utilizes the MAX30102 heart-rate/SpO2 sensor with integrated red and IR LEDs. The low-power step-down converter (MAX1921) converts the 2 V to 5.5 V supply input and generates the 1.8 V rail for the heart-rate sensor. The MAX14595 level translator provides an interface between the heart-rate/SpO2 sensor and the controller board which uses a different logic level.

This tiny development board (.5” x .5”) is perfect for wearable projects and may be placed on a finger, earlobe, or other fleshy extremity to accurately detect heart rate. Users will need to provide a 2 V to 5.5 V power input and it operates at less than 5.5 mW.  This versatile module works with many types of microcontrollers that have I²C interfaces. The Arduino and mbed platforms are available for quick testing, development, and system integration. A basic, open source heart-rate and SpO2 algorithm is included in the example firmware. The Arduino and mbed example firmware have been tested on the following development platforms:

The complete source code is provided to speed up customer development. Code documentation can be found in the corresponding firmware platform files.