AFE for optical bio-sensing applications such as heart-rate monitoring

Available now from Farnell element14, the Texas Instruments (TI) AFE4404 is an analog front-end (AFE) for optical bio-sensing applications, such as heart-rate monitoring (HRM) and saturation of peripheral capillary oxygen (SpO2). The device supports three switching light-emitting diodes (LEDs) and a single photodiode. The current from the photodiode is converted into voltage by the transimpedance amplifier (TIA) and digitized using an analog-to-digital converter (ADC). The ADC code can be read out using an I 2C interface. The AFE also has a fully-integrated LED driver with a 6-bit current control. The device has a high dynamic range transmit and receive circuitry that helps with the sensing of very small signal levels. Applications include optical heart-rate monitoring (HRM), heart-rate variability (HRV), pulse oximetry (SpO2 measurement), VO2 max and calorie expenditure.