Integrated Optical Module for Smoke Detection Data Sheet ADPD188BI FEATURES GENERAL DESCRIPTION 3.8 mm 5.0 mm 0.9 mm module with integrated optical The ADPD188BI is a complete photometric system for smoke components detection using optical dual wavelength technology. The module 1 blue LED, 1 IR LED, and 2 photodiodes integrates a highly efficient photometric front end, two light 2 external inputs for other sensors (for example, carbon emitting diodes (LEDs), and two photodiodes (PDs). These monoxide (CO) and temperature) items are housed in a custom package that prevents light from Three 370 mA LED drivers going directly from the LED to the photodiode without first 20-bit burst accumulator enabling 20 bits per sample period entering the smoke detection chamber. On-board sample to sample accumulator enabling up to The front end of the application specific integrated circuit 27 bits per data read (ASIC) consists of a control block, a 14-bit analog-to-digital Optimized SNR for signal limited cases converter (ADC) with a 20-bit burst accumulator, and three 2 I C or SPI communications flexible, independently configurable LED drivers. The control circuitry includes flexible LED signaling and synchronous APPLICATIONS detection. The analog front end (AFE) features best-in-class Smoke detection rejection of signal offset and corruption due to modulated interference commonly caused by ambient light. The data 2 output and functional configuration occur over a 1.8 V I C interface or serial peripheral interface (SPI) port. FUNCTIONAL BLOCK DIAGRAM VDD1 VDD2 PDC ADPD188BI PD1 EXT IN1 CH1 BPF 1 INTEGRATOR TIA VREF VREF PD2 1F EXT IN2 CH2 BPF 1 INTEGRATOR TIA VREF PDC PDET1 PD3 CS CH3 BPF 1 INTEGRATOR SCLK TIME SLOT A TIA VREF DATA MOSI PDET2 MISO 14-BIT PD4 ADC BPF CH4 TIME SLOT B 1 INTEGRATOR DATA SDA VLED1 AFE CONFIGURATION, TIME SLOT A SCL TIA VREF VLED3 AFE CONFIGURATION, GPIO0 TIME SLOT B IR BLUE DIGITAL GPIO1 INTERFACE AND LED1/DNC LED1 DRIVER CONTROL LED3 DRIVER LED3/DNC LED2 DRIVER LED2 LGND AGND DGND NOTES 1. DNC = DO NOT CONNECT. DO NOT CONNECT TO THIS PIN WHEN USING INTERNAL LEDs. Figure 1. Rev. B 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. 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Trademarks and registered trademarks are the property of their respective owners. 16385-001ADPD188BI Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Typical Connection Diagram ................................................... 24 Applications ...................................................................................... 1 Land Pattern ............................................................................... 24 General Description ......................................................................... 1 Recommended Start-Up Sequence .......................................... 24 Functional Block Diagram .............................................................. 1 Reading Data ............................................................................... 25 Revision History ............................................................................... 2 Clocks and Timing Calibration ................................................ 26 Specifications .................................................................................... 4 Optional Timing Signals Available on GPIO0 and GPIO1 . 27 Analog Specifications ................................................................... 6 LED Driver Pins and LED Supply Voltage ............................. 28 Digital Specifications ................................................................... 7 LED Driver Operation ............................................................... 28 Timing Specifications .................................................................. 8 Determining the Average Current ........................................... 29 Absolute Maximum Ratings ......................................................... 10 Determining CVLED ..................................................................... 29 Thermal Resistance .................................................................... 10 Using External LEDs ................................................................. 30 Recommended Soldering Profile ............................................. 10 Calculating Current Consumption .......................................... 30 ESD Caution................................................................................ 10 Optimizing SNR ......................................................................... 30 Pin Configuration and Function Descriptions .......................... 11 TIA ADC Mode .......................................................................... 33 Typical Performance Characteristics ........................................... 12 Float Mode .................................................................................. 35 Theory of Operation ...................................................................... 15 Recommended Configuration for Smoke Detector Application .................................................................................. 42 Introduction ................................................................................ 15 Using a Smoke Chamber with the ADPD188BI .................... 42 Optical Components .................................................................. 15 Register Details ............................................................................... 43 Dual Time Slot Operation ......................................................... 16 LED Control Registers ............................................................... 47 Time Slot Switch ......................................................................... 17 AFE Configuration Registers .................................................... 49 Adjustable Sampling Frequency............................................... 18 Float Mode Registers ................................................................. 53 External Synchronization for Sampling .................................. 18 System Registers ......................................................................... 55 State Machine Operation .......................................................... 18 ADC Registers ............................................................................ 60 Normal Mode Operation and Data Flow ................................ 19 Data Registers ............................................................................. 61 Communications Interface ........................................................... 21 2 Outline Dimensions ....................................................................... 62 I C Interface ................................................................................ 21 Ordering Guide .......................................................................... 62 SPI Port ........................................................................................ 22 Applications Information .............................................................. 24 REVISION HISTORY 9/2020Rev. A to Rev. B Changes to Figure 12 and Figure 13 ............................................ 13 Changes to Typical Performance Characteristics Section ........ 12 Added Figure 19 and Figure 20 Renumbered Sequentially ..... 14 Deleted Figure 18 Renumbered Sequentially ............................ 14 Changes to Figure 21 ..................................................................... 15 Changes to Figure 18 and Figure 19 ............................................ 14 Changes to Dual Time Slot Operation Section and Table 11 .. 16 Changes to Time Slot Switch Section .......................................... 17 11/2019Rev. 0 to Rev. A Changes to Adjustable Sampling Frequency Section ................ 18 Changes to Table 1 ........................................................................... 5 Changes to Averaging Section ...................................................... 20 2 Added Endnote 1, Table 2 Renumbered Sequentially ............... 6 Changes to I C Interface Section .................................................. 21 Changed Output Voltage Level Parameter to SDA Output Changes to Reading Data Using the FIFO Section .................... 25 Voltage Level Parameter, Table 3 ................................................... 7 Changes to Calibrating the 32 kHz Clock Section..................... 27 Added Endnote 1, Table 6 ............................................................. 10 Deleted Optimizing SNR per Watt in a Signal Limited System Changes to Thermal Resistance Section...................................... 10 Section .............................................................................................. 29 Changes to Figure 10 and Figure 11 ............................................ 12 Change to Determining the Average Current Section .............. 29 Rev. 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