A discrete optical implementation will require an optical AFE with good ambient light rejection, good SNR, low power, and other integrated features which Maxim is the leader in. Additionally, discrete solutions are best used for wrist wearable applications while a fully integrated module such as the MAX30101 or MAX30102 is designed for finger-based applications. The modules that Maxim develops are guaranteed to operate within the data sheet specifications and as such greatly decrease design time, process control, parts procural, assembly, and testing which would be required for an accurate discrete solution.