Analog Devices Inc. ADPD188GG Integrated Optical Module
Analog Devices ADPD188GG Integrated Optical Module is a complete photometric system designed for use in applications such as optical heart rate monitoring, pulse oximetry, and continuous non-invasive blood pressure measurements.
The module is designed to simplify PPG measurements and includes two 525 nm green LEDs and two IR photodetectors with IR cut filters. It uses synchronous measurements for best-in-class rejection of both AC and DC ambient light interference.
It's housed in a custom 24-terminal optical LGA package that ensures LED light pulses pass through the subjected before entering the photodiodes. For applications that will be exposed to moisture, the sensor can be placed behind a window up to 0.7mm thick with an air gap up to 0.5mm.
This module also includes a photometric front-end ASIC with analog signal processing, a 14-bit ADC, DSP functions, and I2C and SPI interfaces. It offers a 20-bit burst accumulator that enables a 20-bit maximum range for each sampling period, and a sample-to-sample accumulator that averages between sampling periods and enables up to 27-bits per data read.
The ADPD188GG also includes three flexible 370 mA programmable pulsed LED current sources, with configurable pulse magnitude, duration, and pulse count. These can be used to drive external LEDs, and the module offers inputs for external sensors, allowing for application customization, such as connecting the ADPD188GG to the AD8233 for synchronous ECG and PPG measurements.
This component has a unique float mode that is used to maximize SNR in low light conditions, the photodiode is preconditioned and disconnected from the receive signal path. The capacitance of the photodiode is then charged by ambient light, pulsed LED light, or both.
After the float time has expired, the photodiode is switched back into the receive path and the accumulated charge is sensed by the ADC. This method maximizes the charge processed to minimize the noise in the measurement, and designers can optimized float time and LED drive current to meet application needs. To learn more about the capabilities and flexibility of the Analog Devices ADPD188GG Integrated Optical Module and its use in measuring biomedical signals, visit Mouser.com.
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