SBOS681C July   2014  – November 2017 OPT3001


  1. Features
  2. Applications
    1.     Spectral Response: The OPT3001 and Human Eye
  3. Description
    1.     Block Diagram
  4. Revision History
  5. Pin Configuration and Functions
    1.     Pin Functions
  6. Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Human Eye Matching
      2. 7.3.2 Automatic Full-Scale Range Setting
      3. 7.3.3 Interrupt Operation, INT Pin, and Interrupt Reporting Mechanisms
      4. 7.3.4 I2C Bus Overview
        1. Serial Bus Address
        2. Serial Interface
    4. 7.4 Device Functional Modes
      1. 7.4.1 Automatic Full-Scale Setting Mode
      2. 7.4.2 Interrupt Reporting Mechanism Modes
        1. Latched Window-Style Comparison Mode
        2. Transparent Hysteresis-Style Comparison Mode
        3. End-of-Conversion Mode
        4. End-of-Conversion and Transparent Hysteresis-Style Comparison Mode
    5. 7.5 Programming
      1. 7.5.1 Writing and Reading
        1. High-Speed I2C Mode
        2. General-Call Reset Command
        3. SMBus Alert Response
    6. 7.6 Register Maps
      1. 7.6.1 Internal Registers
        1. Register Descriptions
          1. Result Register (offset = 00h)
            1. Table 7. Result Register Field Descriptions
          2. Configuration Register (offset = 01h) [reset = C810h]
            1. Table 10. Configuration Register Field Descriptions
          3. Low-Limit Register (offset = 02h) [reset = C0000h]
            1. Table 11. Low-Limit Register Field Descriptions
          4. High-Limit Register (offset = 03h) [reset = BFFFh]
            1. Table 13. High-Limit Register Field Descriptions
          5. Manufacturer ID Register (offset = 7Eh) [reset = 5449h]
            1. Table 14. Manufacturer ID Register Field Descriptions
          6. Device ID Register (offset = 7Fh) [reset = 3001h]
            1. Table 15. Device ID Register Field Descriptions
  8. Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Electrical Interface
      2. 8.1.2 Optical Interface
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. Optomechanical Design
        2. Dark Window Selection and Compensation
      3. 8.2.3 Application Curves
    3. 8.3 Do's and Don'ts
  9. Power-Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information
    1. 12.1 Soldering and Handling Recommendations
    2. 12.2 DNP (S-PDSO-N6) Mechanical Drawings



Optical Interface

The optical interface is physically located within the package, facing away from the PCB, as specified by the Sensor Area in Figure 37.

Physical components, such as a plastic housing and a window that allows light from outside of the design to illuminate the sensor (see Figure 30), can help protect the OPT3001 and neighboring circuitry. Sometimes, a dark or opaque window is used to further enhance the visual appeal of the design by hiding the sensor from view. This window material is typically transparent plastic or glass.

Any physical component that affects the light that illuminates the sensing area of a light sensor also affects the performance of that light sensor. Therefore, for optimal performance, make sure to understand and control the effect of these components. Design a window width and height to permit light from a sufficient field of view to illuminate the sensor. For best performance, use a field of view of at least ±35°, or ideally ±45° or more. Understanding and designing the field of view is discussed further in application report SBEA002, OPT3001: Ambient Light Sensor Application Guide.

The visible-spectrum transmission for dark windows typically ranges between 5% to 30%, but can be less than 1%. Specify a visible-spectrum transmission as low as, but no more than, necessary to achieve sufficient visual appeal because decreased transmission decreases the available light for the sensor to measure. The windows are made dark by either applying an ink to a transparent window material, or including a dye or other optical substance within the window material itself. This attenuating transmission in the visible spectrum of the window creates a ratio between the light on the outside of the design and the light that is measured by the OPT3001. To accurately measure the light outside of the design, compensate the OPT3001 measurement for this ratio; an example is given in Dark Window Selection and Compensation.

Ambient light sensors are used to help create ideal lighting experiences for humans; therefore, the matching of the sensor spectral response to that of the human eye response is vital. Infrared light is not visible to the human eye, and can interfere with the measurement of visible light when sensors lack infrared rejection. Therefore, the ratio of visible light to interfering infrared light affects the accuracy of any practical system that represents the human eye. The strong rejection of infrared light by the OPT3001 allows measurements consistent with human perception under high-infrared lighting conditions, such as from incandescent, halogen, or sunlight sources.

Although the inks and dyes of dark windows serve their primary purpose of being minimally transmissive to visible light, some inks and dyes can also be very transmissive to infrared light. The use of these inks and dyes further decreases the ratio of visible to infrared light, and thus decreases sensor measurement accuracy. However, because of the excellent infrared rejection of the OPT3001, this effect is minimized, and good results are achieved under a dark window with similar spectral responses to those shown in Figure 31.

For best accuracy, avoid grill-like window structures, unless the designer understands the optical effects sufficiently. These grill-like window structures create a nonuniform illumination pattern at the sensor that make light measurement results vary with placement tolerances and angle of incidence of the light. If a grill-like structure is desired, the OPT3001 is an excellent sensor choice because it is minimally sensitive to illumination uniformity issues disrupting the measurement process.

Light pipes can appear attractive for aiding in the optomechanical design that brings light to the sensor; however, do not use light pipes with any ambient light sensor unless the system designer fully understands the ramifications of the optical physics of light pipes within the full context of his design and objectives.