Photometric Front Ends Data Sheet ADPD1080/ADPD1081 FEATURES GENERAL DESCRIPTION Multifunction photometric front end The ADPD1080/ADPD1081 are highly efficient, photometric Fully integrated AFE, ADC, LED drivers, and timing core front ends, each with an integrated 14-bit analog-to-digital Enables ambient light rejection capability without the need converter (ADC) and a 20-bit burst accumulator that works for photodiode optical filters with flexible light emitting diode (LED) drivers. The ADPD1080/ Three 370 mA LED peak current drivers ADPD1081 stimulate an LED and measures the corresponding Flexible, multiple, short LED pulses per optical sample optical return signal. The data output and functional configuration 2 20-bit burst accumulator enabling 20 bits per sample period occur over a 1.8 V I C interface on the ADPD1080 or a serial On-board sample to sample accumulator, enabling up to port interface (SPI) on the ADPD1081. The control circuitry 27 bits per data read includes flexible LED signaling and synchronous detection. Low power operation The analog front end (AFE) features rejection of signal offset and 2 SPI, I C interface, and 1.8 V analog/digital core corruption due to modulated interference commonly caused by Flexible sampling frequency ranging from 0.122 Hz to 2700 Hz ambient light without the need for optical filters or dc cancellation FIFO data operation circuitry that requires external control. Qualified for automotive applications Couple the ADPD1080/ADPD1081 with a low capacitance APPLICATIONS photodiode of <100 pF for optimal performance. The ADPD1080/ Wearable health and fitness monitors ADPD1081 can be used with any LED. The ADPD1080 is available Clinical measurements, for example, SpO2 in a 16-ball, 2.46 mm 1.4 mm WLCSP and a 28-lead, 4 mm Industrial monitoring 4 mm LFCSP. The SPI only version, ADPD1081, is available in Background light measurements a 17-ball, 2.46 mm 1.4 mm WLCSP. Rev. C Document Feedback Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. Tel: 781.329.4700 20182020 Analog Devices, Inc. All rights reserved. No license is granted by implication or otherwise under any patent or patent rights of Analog Technical Support www.analog.com Devices. Trademarks and registered trademarks are the property of their respective owners. ADPD1080/ADPD1081 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 LED Driver Pins and LED Supply Voltage ............................. 32 Applications ...................................................................................... 1 LED Driver Operation ............................................................... 32 General Description ......................................................................... 1 Determining the Average Current ........................................... 33 Table of Contents ............................................................................. 2 Determining CVLED ..................................................................... 33 Revision History ............................................................................... 3 LED Inductance Considerations .............................................. 34 Functional Block Diagrams ............................................................. 4 Recommended Start-Up Sequence .......................................... 34 Specifications .................................................................................... 6 Reading Data ............................................................................... 34 Temperature and Power Specifications .................................... 6 Clocks and Timing Calibration ................................................ 36 Performance Specifications......................................................... 7 Optional Timing Signals Available on GPIO0 and GPIO1 . 36 Analog Specifications ................................................................... 8 Calculating Current Consumption .......................................... 38 Digital Specifications ................................................................. 10 Optimizing SNR per Watt ........................................................ 39 Timing Specifications ................................................................ 11 Optimizing Power by Disabling Unused Channels and Amplifiers .................................................................................... 41 Absolute Maximum Ratings ......................................................... 13 Optimizing Dynamic Range for High Ambient Light Thermal Resistance .................................................................... 13 Conditions ................................................................................... 42 Recommended Soldering Profile ............................................. 13 TIA ADC Mode .......................................................................... 43 ESD Caution................................................................................ 13 Pulse Connect Mode .................................................................. 46 Pin Configurations and Function Descriptions ......................... 14 Synchronous ECG and PPG Measurement Using TIA ADC Typical Performance Characteristics ........................................... 17 Mode ............................................................................................ 46 Theory of Operation ...................................................................... 19 Float Mode .................................................................................. 47 Introduction ................................................................................ 19 Register Listing ............................................................................... 54 Dual Time Slot Operation ......................................................... 19 LED Control Registers ............................................................... 58 Time Slot Switch ......................................................................... 20 AFE Configuration Registers .................................................... 60 Adjustable Sampling Frequency............................................... 23 Float Mode Registers ................................................................. 64 State Machine Operation .......................................................... 24 System Registers ......................................................................... 66 Normal Mode Operation and Data Flow ................................ 24 ADC Registers ............................................................................ 71 AFE Operation ............................................................................ 26 Data Registers ............................................................................. 72 AFE Integration Offset Adjustment ........................................ 26 Required Start-Up Load Procedure ......................................... 72 2 I C Serial Interface...................................................................... 28 Outline Dimensions ....................................................................... 73 SPI Port ........................................................................................ 29 Ordering Guide .......................................................................... 74 Applications Information .............................................................. 31 Automotive Products ................................................................ 74 Typical Connection Diagram ................................................... 31 Rev. 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