MAX30101 High-Sensitivity Pulse Oximeter and Heart-Rate Sensor for Wearable Health Functional Diagram VLED+ VDD AMBIENT LIGHT RED IR GREEN CANCELLATION ANALOG DIGITAL SCL VISIBLE+IR SDA ADC DIGITAL I2C FILTER DATA REGISTER COMMUNICATION INT 660nm 880nm 527nm DIE TEMP ADC OSCILLATOR LED DRIVERS MAX30101 N.C. N.C. N.C. GND PGND Detailed Description The device output data is relatively insensitive to the The MAX30101 is a complete pulse oximetry and heart- wavelength of the IR LED, where the red LED’s wave- rate sensor system solution module designed for the length is critical to correct interpretation of the data. An demanding requirements of wearable devices. The SpO2 algorithm used with the MAX30101 output signal MAX30101 maintains a very small solution size without can compensate for the associated SpO2 error with ambient sacrificing optical or electrical performance. Minimal temperature changes. external hardware components are required for integra- LED Driver tion into a wearable system. The MAX30101 integrates red, green, and IR LED drivers The MAX30101 is fully adjustable through software regis- to modulate LED pulses for SpO ters, and the digital output data can be stored in a 32-deep 2 and HR measurements. The LED current can be programmed from 0 to 50mA FIFO within the IC. The FIFO allows the MAX30101 to be with proper supply voltage. The LED pulse width can be connected to a microcontroller or processor on a shared bus, where the data is not being read continuously from programmed from 69µs to 411µs to allow the algorithm to optimize SpO the MAX30101’s registers. 2 and HR accuracy and power consumption based on use cases. SpO2 Subsystem The SpO2 subsystem contains ambient light cancellation (ALC), a continuous-time sigma-delta ADC, and propri- etary discrete time filter. The ALC has an internal Track/ Hold circuit to cancel ambient light and increase the effec- tive dynamic range. The SpO2 ADC has a programmable full-scale ranges from 2µA to 16µA. The ALC can cancel up to 200µA of ambient current. The internal ADC is a continuous time oversampling sigma-delta converter with 18-bit resolution. The ADC sampling rate is 10.24MHz. The ADC output data rate can be programmed from 50sps (samples per second) to 3200sps. Temperature Sensor The MAX30101 has an on-chip temperature sensor for calibrating the temperature dependence of the SpO2 subsystem. The temperature sensor has an inherent resolution 0.0625°C. www.maximintegrated.com Maxim Integrated │ 10