A photoplethysmogram (PPG) device can be implemented to measure blood volume changes from which vital sign information such as blood oxygen levels and heart rates are derived. In Part 1, we provide discrete power-supply circuit design solutions for best performance using the MAX86171 optical pulse oximeter and heart-rate sensor analog front end (AFE). Part 2 will examine an integrated solution for space-constrained applications.
Switch-mode power supplies (SMPS, also referred to as dc-dc converters) are commonly used in wearable medical and healthcare applications for reasons such as size considerations and power efficiency. Designers can use these power supplies to create battery-operated products that achieve longer lifetimes. Unfortunately, designers are still left to select the appropriate SMPS device followed by creating a suitable circuit board layout that preserves the performance of a biosensing device in their system.