Texas Instruments AFE44S30 Ultra-Low-Power Integrated AFE is intended for optical bio-sensing applications, including as heart-rate monitoring and saturation of peripheral capillary oxygen. The device provides support up to eight switching LEDs and up to four photodiodes. Up to 24 signal phases can be defined, and the signal can be received from each phase in a synchronised manner. The current from the photodiode is converted into a voltage by the trans-impedance amplifier and digitised using an ADC. The ADC code can be stored in a 128-sample FIFO block. The FIFO can be read out using an SPI interface.
The AFE also includes a fully-integrated LED driver with an 8-bit current control. The device has a high dynamic range transmit-and-receive circuitry that helps with the sensing of very small signal levels.
The device is intended for optical heart-rate monitoring for wearables, hearables; heart-rate variability; and pulse oximetry measurements.