The AFE4420 evaluation module (EVM) is a platform for evaluating the AFE4420 device, which is an analog front end (AFE) for optical biosensing applications, such as heart-rate monitoring (HRM) and saturation of peripheral capillary oxygen (SpO2). AFE4420 supports four switching light-emitting diodes (LEDs) and four photodiodes. The current from the photodiode is converted into voltage by the transimpedance amplifier (TIA) and digitized using an analog-to-digital converter (ADC). ADC code can be stored in a 128-sample FIFO with programmable depth. The FIFO depth can be partitioned to accommodate the phases that need to be stored. The FIFO can be read out using either an I2C interface or serial peripheral interface (SPI).
AFE4420 also has a fully-integrated LED driver with an 8-bit current control. The device can be clocked by an external clock or internal oscillator. The device communicates to an external host processor using an I2C interface.
The purpose of the AFE4420EVM is to expedite evaluation and system development activities related to the AFE4420 device.