ADPD1080/ADPD1081 Photometric Front Ends

By Analog Devices Inc 36

ADPD1080/ADPD1081 Photometric Front Ends

ADI’s ADPD1080/ADPD1081 are photometric front ends, each with an integrated 14-bit analog-to-digital converter (ADC) and a 20-bit burst accumulator that works with flexible light emitting diode (LED) drivers. These devices stimulate an LED and measure the corresponding optical return signal. The data output and functional configuration occur over a 1.8 V I2C interface on the ADPD1080 or a serial port interface (SPI) on the ADPD1081. The control circuitry includes flexible LED signaling and synchronous detection.

The analog front end (AFE) features rejection of signal offset and corruption due to modulated interference commonly caused by ambient light without the need for optical filters or DC cancellation circuitry that requires external control.

Couple the ADPD1080/ADPD1081 with a low capacitance photodiode of <100 pF for optimal performance. The devices can be used with any LED. The ADPD1080 is available in a 16-ball, 2.46 mm × 1.4 mm WLCSP and a 28-lead, 4 mm × 4 mm LFCSP. The SPI only version, ADPD1081, is available in a 17-ball, 2.46 mm × 1.4 mm WLCSP. The ADPD1080/ADPD1081 is ideal for clinical measuring, industrial monitoring, and fitness monitor applications.

Features
  • Multifunction photometric front end
  • Integrated AFE, ADC, LED drivers and timing core
  • Enables ambient light rejection capability without the need for photodiode optical filters
  • Three 370 mA LED peak current drivers
  • Flexible, multiple, short LED pulses per optical sample
  • 20-bit burst accumulator enabling 20-bits per sample period
  • On-board sample to sample accumulator, enabling up to 27-bits per data read
  • Low power operation
  • SPI, I2C interface, and 1.8 V analog/digital core
  • Flexible sampling frequency ranging from 0.122 Hz to 2,700 Hz
  • FIFO data operation
Applications
  • Clinical measurements
  • Industrial monitoring
  • Wearable health fitness monitors 
  • Background light measurements

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