SNAS778A June   2021  – September 2021 HDC3020 , HDC3021 , HDC3022

ADVANCE INFORMATION  

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Device Comparison
  6. Pin Configuration and Functions
  7. Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Switching Characteristics
    7. 7.7 Timing Diagram
    8. 7.8 Typical Characteristics
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Factory Installed Polyimide Tape
      2. 8.3.2  Factory Installed IP67 Protection Cover
      3. 8.3.3  Measurement of Relative Humidity and Temperature
      4. 8.3.4  Drift Correction: Accuracy Restoration
      5. 8.3.5  NIST Traceability of Relative Humidity and Temperature Sensor
      6. 8.3.6  Measurement Modes: Trigger-On Demand vs. Auto Measurement
      7. 8.3.7  Heater
      8. 8.3.8  ALERT Output With Programmable Interrupts
      9. 8.3.9  Checksum Calculation
      10. 8.3.10 Programmable Offset of Relative Humidity and Temperature Results
    4. 8.4 Device Functional Modes
      1. 8.4.1 Sleep Mode vs. Measurement Mode
    5. 8.5 Programming
      1. 8.5.1 I2C Interface
      2. 8.5.2 I2C Serial Bus Address Configuration
      3. 8.5.3 I2C Write - Send Device Command
      4. 8.5.4 I2C Read - Retrieve Single Data Result
      5. 8.5.5 I2C Read - Retrieve Multi Data Result
      6. 8.5.6 I2C Repeated START - Send Command and Retrieve Data Results
      7. 8.5.7 Command Table and Detailed Description
        1. 8.5.7.1 Reset
          1. 8.5.7.1.1 Soft Reset
          2. 8.5.7.1.2 I2C General Call Reset
        2. 8.5.7.2 Trigger-On Demand
        3. 8.5.7.3 Auto Measurement Mode
          1. 8.5.7.3.1 Auto Measurement Mode: Enable and Configure Measurement Interval
          2. 8.5.7.3.2 Auto Measurement Mode: Measurement Readout
          3. 8.5.7.3.3 Auto Measurement Mode: Exit
          4. 8.5.7.3.4 Auto Measurement Mode: Measurement History Readout
          5. 8.5.7.3.5 Override Default Device Power-On and Device-Reset State
        4. 8.5.7.4 ALERT Output Configuration
          1. 8.5.7.4.1 ALERT Output: Environmental Tracking of Temperature and Relative Humidity
          2. 8.5.7.4.2 ALERT Output: Representation of Environmental Thresholds and Default Threshold Values
          3. 8.5.7.4.3 ALERT Output: Steps to Calculate and Program Environmental Thresholds
          4. 8.5.7.4.4 ALERT Output: Deactivation of Environmental Tracking
          5. 8.5.7.4.5 ALERT Output: Transfer Thresholds into Non-Volatile Memory
        5. 8.5.7.5 Programmable Measurement Offset
          1. 8.5.7.5.1 Representation of Offset Value and Factory Shipped Default Value
          2. 8.5.7.5.2 Factory Shipped Default Offset Values
          3. 8.5.7.5.3 Calculate Relative Humidity Offset Value
          4. 8.5.7.5.4 Calculate Temperature Offset Value
          5. 8.5.7.5.5 Write an Offset Value
          6. 8.5.7.5.6 Verify a Programmed Offset Value
        6. 8.5.7.6 Status Register
        7. 8.5.7.7 Heater: Enable and Disable
        8. 8.5.7.8 Read NIST ID/Serial Number
  9. Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
    3. 11.3 Storage and PCB Assembly
      1. 11.3.1 Storage and Handling
      2. 11.3.2 Soldering Reflow
      3. 11.3.3 Rework
      4. 11.3.4 Exposure to High Temperature and High Humidity Conditions
      5. 11.3.5 Bake/Rehydration Procedure
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information
    1. 13.1 Package Option Addendum
    2. 13.2 Tape and Reel Information

Package Options

Mechanical Data (Package|Pins)
  • DEF|8
Thermal pad, mechanical data (Package|Pins)
Orderable Information
ALERT Output: Representation of Environmental Thresholds and Default Threshold Values

The Set High Alert, Clear High Alert, Set Low Alert, and Clear Low Alert thresholds are each represented by a truncated 16 bit value, as illustrated Figure 8-26. The 7 MSBs from a relative humidity measurement are concatenated with the 9 MSBs from a temperature measurement. The actual temperature and relative humidity measurement result are always stored as a 16-bit value, but when compared against the programmed threshold values, due to the truncated representation, there is a resolution loss of 0.5°C in temperature and a 1% resolution loss in relative humidity.

GUID-3AEDC6E1-45D9-458B-9300-59D7507CECDF-low.gifFigure 8-26 Representation of ALERT Threshold Value Using Combined RH and T

The default values of the relative humidity and temperature thresholds after Power Up/Cycle, Hardware Reset, and Soft Reset are documented in Table 8-6 below. Refer to Table 8-3 for the appropriate command to re-program the thresholds.

Table 8-6 Default Value of ALERT Thresholds
ALERT THRESHOLDDEFAULT RH THRESHOLDDEFAULT T THRESHOLDHEX VALUECRC
Set High Alert80% RH60°C0xCD330xFD
Clear High Alert79% RH58°C0xC92D0x22
Set Low Alert20% RH-10°C0x34660xAD
Clear Low Alert22% RH-9°C0x38690x37