Analog Front-End for Pulse Oximeter
Created: Aug 18, 2015
No description available.
Pulse oximeter is a medical device used to measure the oxygen saturation of the blood. It uses a light emitter, with red and infrared LEDs, that shines through a semi-transparent part of blood flow. The principle of oximetry is based on the red and infrared light absorption characteristic of oxygenated and deoxygenated hemoglobin and the pulsating nature of blood flow in the arteries to determine the oxygenation status in the body. Oxygenated hemoglobin absorbs more infrared lights and allows more red lights to pass through. Deoxygenated hemoglobin absorbs more red lights and allows more infrared lights to pass through.
This circuit is an analog front-end specifically designed for pulse oximeters and heart rate monitors. The analog front-end consists of a low-noise receiver channel with an integrated analog-to-digital converter (ADC), an LED transmit section, and diagnostics for sensor and LED fault detection. The device is a configurable timing controller. This flexibility enables the user to have complete control of the device timing characteristics. To ease clocking requirements and provide a low-jitter clock to the analog front-end, an oscillator is also integrated that functions from an external crystal. The device communicates to an external microcontroller or host processor using an SPI interface. This design features TE Connectivity’s 1-5747150-3, a rugged DB9 connector. Its front metal, full metal, and plastic shell features allow user to choose a connector with the right durability. Also, it has UL94V-0 rated thermoplastic housing, and is compatible with SCSI and VESA standards.
This circuit is designed for analog front-end of pulse oximeters, heart rate monitors (HRM) and other medical monitoring systems such as ECG. It can also be used in optical HRM and other industrial photometry applications.