Texas Instruments AFE4432 Integrated Analog Front End (AFE)

Texas Instruments AFE4432 Integrated Analog Front End (AFE) is for optical bio-sensing applications, such as heart-rate monitoring (HRM) and saturation of peripheral capillary oxygen (SpO₂). The device supports up to 4 switching light-emitting diodes (LEDs) and up to three photodiodes (PDs). The AFE has two LED drivers, each with 8-bit current control. The Texas Instruments AFE4432 has a high dynamic range transmit-and-receive circuitry that helps with sensing very small signal levels. Up to 12 signal phase sets can be defined, each phase set comprising a combination of LED and Ambient phases. Low noise offset DACs at the receiver inputs can be automatically controlled to cancel DC from Ambient and LED light. The current from the PDs in each phase is converted into voltage by TIAs, filtered, and then digitized using a typical ADC. The ADC code can be stored in a 160-sample FIFO block. The FIFO can be read out using an SPI or I²C interface.