Texas Instruments AFE4462 Ultra-Small Integrated Analog Front-End (AFE) is an AFE for optical bio-sensing applications, such as saturation of peripheral capillary oxygen (SpO2) and heart-rate monitoring (HRM). The device supports up to four photodiodes (PDs) and up to 16 switching light-emitting diodes (LEDs). The AFE has two LED drivers, each with an 8-bit current control. The Texas Instruments AFE4462 has a high dynamic range transmit-and-receive circuitry that helps sense very small signal levels. Up to 16 signal phase sets can be defined, each phase set comprising a combination of ambient phases and LED. Low noise offset DACs at the receiver inputs can be automatically controlled to cancel DC from LED and ambient light. The current from each of the four PDs in each phase is converted into voltage by TIAs, filtered, and then digitized using a common ADC. The ADC code can be stored in a 256-sample FIFO block. The FIFO can be read out using an SPI or I2C interface.
