The AFE4404YZPT is an Analog Front-End 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 I²C 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.
● Transmitter - supports common anode LED configuration
● Transmitter - 100dB dynamic range
● Transmitter - 6-bit programmable LED current to 50mA (Extendable to 100 mA)
● Transmitter - Programmable LED on-time
● Transmitter - Simultaneous Support of 3 LEDs for Optimized SpO2, HRM or multi-wavelength HRM
● 24-bit Representation of the current input from a photodiode in twos complement format
● Receiver - Individual DC offset subtraction DAC at TIA input for each LED and ambient phase
● Receiver - Digital ambient subtraction at ADC output
● Receiver - 10 kR to 2 MR Programmable transimpedance gain
● Receiver - 100dB Dynamic range
● Receiver - Dynamic power-saving mode to reduce current to less than 200µA
● 10 to 1000SPS Pulse frequency
● Flexible pulse sequencing and timing control
● Flexible clock options - External 4 to 60MHz Input Clock, Internal 4MHz Oscillator
