Today, it seems like everyone has a fitness tracker for logging exercise activity or a smartwatch that includes some of these functions. However, monitoring heart rate and pulse in these devices requires a compact sensor solution that can capture the wearer’s pulse without an external contact probe, like those used in a hospital. Sometimes, in these components, the sensor and the processor interface are disconnected. Still, integrated solutions enable smaller device footprints without losing accuracy.
The MAX30102 is one integrated sensor interface option that provides highly accurate heart rate monitoring and pulse oximetry functions in a single package. Unlike other heart monitoring solutions and pulse oximetry sensor interfaces, this component integrates an IR light source, a sensor interface, and the required DSP block in the same package. Designers looking to include a health monitoring sensor and processing interface in a single package, but do not need to develop a highly integrated SoC, should refer to the MAX30102 datasheet to see its advantages.
Meet the New MAX30102
The MAX30102 is a combined pulse oximetry and heart rate sensor interface designed for small wearables or personal health monitoring devices. Compared to other components on the market, the MAX30102 is the first to integrate the following features and components into a single package with a small SMD footprint:
- DSP block for processing heart rate and pulse oximetry signals.
- LED driver block, red/IR LED, and sensor on-die with cover glass integrated into the package.
- Integrated FIFO memory block for storing and providing readings to an external processor via an I2C bus interface.
- Adjustable SpO2 range and sample rate control.
- Integrated temperature sensing and compensation circuit.
- Ambient light filtering and compensation.
Although primarily intended for personal health monitoring, the device can interface with any standard processor via its I2C bus interface. The use of I2C in this component is advantageous, as it helps minimize the total circuit footprint by eliminating the need for additional passives for configuration. Other possible uses include PDAs, tablets, and smartphones.
The image below shows the package outline and a typical application circuit from the MAX30102 datasheet. The diagram shows that minimal external hardware (only 3 resistors and 4 capacitors) is required to interface and connect the MAX30102 to an external processor.
Package outline (left) and application circuit (right) for the MAX30102
A Summary of the MAX30102 Datasheet
The MAX30102 datasheet lists the core specifications and data format used in the internal registry to read/write data and configure the device.
|Input voltage||1.7 to 2.0 V|
|LED voltage||3.1 to 5.0 V|
|LED characteristics||880 nm (IR) or 660 nm (red) emission with 30 nm and 20 nm FWHM, respectively|
|Rated SNR||Up to 89 dB|
|Analog interface||16-bit ADC|
Much like other components from Maxim Integrated, this device requires an external driver to be written into the host MCU/SoC firmware to access and configure the component. To help developers get started building a new application with the MAX30102, Maxim Integrated provides a useful reference design with firmware that interfaces with an Arduino or MBED-compatible processor. This reference design can be found on the Maxim Integrated website (MAXREFDES117#); it contains example source code with an algorithm for heart rate and SpO2 determination from the digital output from this component. Another reference design that includes a PCB layout and schematics in 7 ECAD software formats is the MAXREFDES1043.
Due to the highly integrated nature of this component, there are few alternatives from other manufacturers. However, Maxim Integrated offers different reference designs and other components in its biosensing product line.
Finding Other Maxim Integrated Reference Designs
Maxim Integrated is known for its high-quality reference designs, which normally include a current BOM, packaging design ideas, and firmware examples for embedded development. Maxim Integrated has several reference designs for use by health monitoring designers, including MAXREFDES103 and MAXREFDES220. For a much more highly integrated solution, where SpO2, heart rate, and blood pressure sensor interfaces are integrated into the processor, designers might consider using the MAX32630 MCU. While this other MCU component is more integrated, it might not offer the level of computing available in a processor from another vendor. The advantage of the MAX30102 is its ability to add on to more powerful MCUs or MPUs from another manufacturer.
When you need to find technical documentation like the MAX30102 datasheet, PCB footprints, or sourcing information from major distributors, try using the electronics search engine features in Ultra Librarian. Ultra Librarian’s platform allows you to find components like the MAX30102 and a range of reference designs from Maxim Integrated and other popular semiconductor manufacturers. Additionally, all ECAD data you’ll find on Ultra Librarian is compatible with popular ECAD applications and will help you streamline your design process.